The United States government’s Special Presidential Envoy for Climate John Kerry declared in 2023, “A lot of people have no clue that agriculture contributes about 33 percent of all the emissions of the world. We can’t get to net zero, we don’t get this job done unless agriculture is front and center as part of the solution.”

Mr. Kerry did not reveal his basis for blaming agriculture as being a full third culprit in causing what was called “global warming,” “climate change, “then “climate chaos,” then “climate crisis.” Shortly after Mr. Kerry’s remarks, United Nations Secretary-General António Guterres referred to the phenomenon as “global boiling.” Mr. Kerry also said nothing to dispel the view that he has never planted a field nor had to bring a crop in on time.

Shortly after Mr. Kerry’s proclamation, while not a farmer, but someone who does produce things like electric cars and spaceships, responded, ““Important to note that what happens on Earth’s surface (eg farming) has no meaningful impact on climate change.” — Tweet by Elon Musk

These statements serve to highlight the recent increased focus by climate change activists on agriculture as a way of life and business that must be brought regulated in order to save the planet from the pernicious effects arising from manmade climate change. This article, written in March 2024, will not recite the record of whether the dire climate-related predictions of the past 30 or so years have come true or not, rather, it will focus on North Carolina agriculture and related climate issues. The reader will not find a recommendation that the truth lies somewhere between Kerry and Musk or that agriculture just needs to make a few compromises.

This article makes the following points:

(1) North Carolina’s climate has not been adversely or abnormally affecting North Carolina agriculture; in fact, NC ag is thriving.

(2) North Carolina agriculture is not causing any climate abnormalities.

(3) North Carolina has not experienced any significant, enduring and unprecedented change in its climate.

(4) North Carolina agriculture (as well as ag in other states and countries) is being subjected to a gradual roll-out of incentive programs and the threat of regulations which pose a risk to food production and the ability of farmers and ranchers to survive.

(5) While government agencies and state employees who deal with farmers and ranchers are under political, career and peer pressure to take a “we can all work through this together” approach, in the long run this approach will have a gradual adverse effect on agriculture.

If the above points sound like they are “pro-ag,” well, they are. Agriculture in North Carolina is thriving and not adversely affected by a climate catastrophe promoted by some. While there are those in government and academia who would counsel farmers and ranchers of the need to gradually adopt various agricultural practices in order to combat climate change, related regulations and programs will gradually turn up the heat on North Carolina agriculture. Like the apologue which has a pot of water heating so gradually that the frog within does not notice it until it is too late and boils to its demise, the one regulation there, the required program here, the elimination of a resource, increasing prices, conditions on government aid, etc… slowly build up until the average farmer is no longer able to make a go of it.

One issue to put to the side is that this article does not address regulations dealing with pollutants and practices affecting our water, soil and air quality. Farmers and ranchers generally are protectors of our water, soil and air and want to do everything they can to protect the environment. It is in their interests and our interests to do so. Instead, this article focuses on the existence, and threat of further, regulatory pressure to deal with the much more nebulous so-called greenhouse gas emissions which are not environmental pollutants which affect the quality of our air.

Lastly, this article will proceed in a question-and-answer format between me and a composite of farmers and ranchers with whom I have communicated and read about to gather background information for this article. The fictional “Farmer” also acts as a literary muse to pose questions in order to advance the dialogue.

Don’t Need a Weatherman to Know Which Way the Wind Blows

As for me, I am from a farming community in the San Joaquin Valley of California. While I also have never had to bring a crop in on time (at least not to make a living) I spent three and half decades learning how to analyze and dissect opinions from experts in areas of science and am a product of a State University program which trained me how to find and provide research-based horticultural information to the public. While my approach to studying the North Carolina climate does not employ algorithms or computer models, it nonetheless is self-learned (with gratefully received guidance from representatives of the National Weather Service and the National Oceanic and Atmospheric Association (NOAA)), transparent and hopefully employs that virtue possessed by many of those who work the land — common sense. And, if that is not sufficient by way of bona fides, then just consider me a commoner pointing out an emperor who is missing some clothes.

As for the farmers and ranchers making up the composite, they grow vines, trees, row crops and raise animals. One of their common questions is along the lines of “Why all of sudden us? We thought we were the good guys.” They feel threatened and anxious about what may be to come by way of programs and increased regulation in the name of “climate.” They fear that while agricultural practices that are now suggested or part of incentive programs, will, under different political circumstances, become imposed on them, as they have in other countries. They are apprehensive that while government officials now say that of course they want to support agriculture, under different future administrations, they will take the position that it is time that the “agriculture industry” (even though the burden would be felt the most by family farms) “just go along to get along” and make untenable sacrifices “for the good of the planet.”

Let’s start the conversation.

Me: Has your farm or ranch in North Carolina been affected by any unusual changes in the climate in the past 30 years?

Farmer: Each year is different. We haven’t had a significant drought since 2007 or so. There have been some hurricanes, but we’ve always had hurricanes in North Carolina. What do the experts say about our weather?

Me: Well, in the first place, they say you are supposed to refer to it as “climate,” not “weather.”

Farmer: I’ll try to remember that.

Me: There was a research study done by two scientists from the State Climate Office of North Carolina in 2002. It was entitled Analysis of Climate Trends in North Carolina (1949–1998) and published in the Environmental International journal. This study started off by noting that North Carolina has one of the most complex climates in the country and that most of the climate trends found were local, not statewide. The study found on a statewide basis that while temperatures in the last 10 years of the study were warmer than usual, they were not warmer than the temperatures experienced in the 1950’s. Maximum temperatures had remained fairly constant and there was no widespread pattern showing increasing minimum temperatures across the state. What is significant about this study is how the authors acknowledge the inherent problems in assessing the statewide climate in North Carolina, including the complex topography, problems with individual weather stations and lack of density of stations statewide, all of which adds to the credibility of their conclusions.

Farmer: Ok, that gets us up to about the turn of the century.

Me: Next up is a report by the State Climate Office of North Carolina which looked at a much longer time period, investigating records back to the late 1800’s. The report found no warming trend in the 113-year study period starting from 1895 through 2008. While there was some warming since the mid-1970’s, it was found to be not unprecedented and similar to the warming observed from 1910–1950. The report was on the State Climate Office website as late as 2015 and probably into 2016 and concluded that in North Carolina there is “no meaningful trend that is associated with global warming.”

Farmer: So, no global warming in North Carolina as of just a few years ago?

Me: Right, although it should be noted that the State Climate Office has since changed Directors.

Farmer: What next?

Me: A 2020 report on North Carolina’s climate through 2018. Unlike the first two studies, this one was commissioned per the order of the newly elected Democratic governor of North Carolina as part of his “Commitment to Address Climate Change and Transition to a Clean Energy Economy.” The report returned to him generally concluded that there has been statewide warming since 1895 and provided predictions based on computer models that in 60–80 years there will be various climate calamities.

Farmer: So, if this report found there was climate change happening in North Carolina, how did it deal with the prior two studies?

Me: It didn’t. The prior studies are not mentioned in the report.

Farmer: Why would the existence of these prior studies not be included in this report which was delivered to the Governor and made available to the public?

Me: Good question.

Farmer: Wasn’t the 2015/16 study still up on the State Climate Office site when the 2020 study was done?

Me: Apparently not. The office’s Director when the prior study was done left for another position in 2016. Somewhere along the line the 2015/16 report was removed from the State Climate Office website.

Farmer: How did you find it?

Me: This 2015 “no global warming occurring in North Carolina” report can only be found on an internet archive service, see: https://web.archive.org/web/20150420025024/http://www.nc-climate.ncsu.edu/climate/climate_change

Farmer: Hmm. Well, in any event did the 2020 report find significant, enduring and unprecedented warming in North Carolina?

Me: No.

Farmer: What do you mean? I thought this report is being used to support the notion that our weather, er, climate, is warming in North Carolina.

Me: It is, but when you sit down and read the lengthy 2020 report you can see it found that statewide there was less than 1°of warming since 1895. The report inexactly concludes that there has been “almost” 1° of warming, but never discloses how much above zero degrees it is. For all we know, it could be 0.0001, or it could be 0.9999, or somewhere in between. It stands to reason that less than 1° Fahrenheit warming over the course of 123 years does not constitute a significant and enduring change in our state’s climate.

Farmer: Well, whatever warming they did find, can you tell from the report if it was unprecedented?

Me: No, because while there were decades of significant higher than normal average temperatures in the 1920’s — 1940’s, the 2020 study only compared a single 10-year time-period from 2009–2018 with another single decade, 1930–39, and found a difference of “about 0.6°” but then moved on without further comparisons with other prior temperature phases in the 1800’s or the first half of the 1900’s. Also, in focusing on just a 10-year period, the report ignored a basic tenet endorsed by the NOAA that at least 30 years of temperature history need to be examined when making comparisons like this.

Farmer: Why is it important to look back into history to determine if current climate patterns are unprecedented?

Me: Two reasons, the first and most basic is that if something has happened before, such as similar warming periods in our climate, then the current climate is not some type of unusual phenomenon, but instead is reflective of the natural ebbs and flows of our climate. Second, historical climate records through the 1950’s are deemed significant by the climatic research community as they occurred during a “pre-industrial” period reflective of natural (that is, non-manmade) climate conditions, see here.

Farmer: This is starting to get a bit technical for me, but to wrap things up, is there anything else to comment on about the 2020 report?

Me: Yes, but instead of nerding out on you and the readers of this article, just click here for three more observations.

Farmer: What about the long-range computer models in the study?

Me: It has become more common for climate scientists to put their prediction models out so far into the future that most of us now living will never know if the predictions come true or not. The predictions in the study go out to the end of the century. There is debate over the accuracy of computer models anyway, but even the State Climate Office of North Carolina has found that the United Nations had been predicting warming over a period of 50 years that never occurred and that, “Unfortunately, the best global climate models we have do not do a good job of simulating the temperature and precipitation patterns over the southeastern US, and NC in particular.”

Farmer: Are there any other North Carolina climate studies we should know about?

Me: Yes, a couple. The National Weather Service has designated six weather stations as Primary Local Climatological Data sites (PLCD) in North Carolina. They are located in Asheville, Charlotte, Greensboro, Raleigh, Wilmington and Hatteras, representing the breadth of the state from east to west. Their locations are depicted on this map.

These “primary” stations are what the National Weather Service also refers to as “First Order” stations and are the highest quality weather stations in the United States, being subject to the most stringent quality control measures.

I figured that with all of the warnings since at least the 1990’s of dire consequences of climate change and the earth declared to have “a fever,” that the temperatures at these six disparately located weather stations would show unprecedented warming in the three categories of average temperature, maximum temperature and minimum temperatures. However, the review (which can be found here) found that in only three out of 18 instances, or 16%, were there rises in average temperatures that also did not have a corresponding rise in the average temperature being measured in a 30-year period starting prior to 1950. In other words, in 84% of these weather stations, the temperatures were similar to those from the years pre-1950.

The second study focused on Wake County, North Carolina and can be found here (it is updated annually). Remember that one of the Primary Local Climatological Sites is located in Wake County. A wide range of elements of the climate were studied (temperatures, snow, humidity, hurricanes, drought and more) and found there were no recent significant, enduring and unprecedented changes in the climate patterns examined. The study also found that within the entire state there is not a problem pattern with drought and that hurricanes are decreasing in intensity and frequency.

Farmer: Ok, I’m studied out — what’s your point about agriculture in all of this.

Me: With recent claims that the sky basically is falling and that the North Carolina climate is in a crisis, agriculture should be taking it on the chin, right? Well, no, in fact, North Carolina agriculture is producing more, on less land, than ever.

Yep, North Carolina agriculture passed the $103.2 billion mark in 2023, its most productive year ever and up from $59 billion in 2005. Agriculture is North Carolina’s #1 industry, employing about one fifth of the state’s workforce. In terms of total agricultural production, the latest USDA figures show that North Carolina’s production rose 234% since 1960 to 2004.

I also am happy to report that it was a banner year for watermelons and giant pumpkins at the State Fair according to the NC Department of Agriculture.

With all the so-called boiling going on and with, as some have said, North Carolina being significantly affected by climate change, people should be avoiding the state and the economy should be declining. Instead, as we all know, North Carolina is a top state to which people from other states are moving and the state economy is quite healthy — in large part due to agriculture.

And, across the United States total agricultural output has tripled since 1948 according to the latest statistics from the USDA.

Around the world, things are dramatically improving. More than 1 billion people have been lifted out of extreme poverty since 1990. Over the decades since 1961, there has been a consistent global uptrend in the per capita calorie supply. Global agricultural yields of crops have increased substantially in the past several decades.

Farmer: Ok, so NC ag is doing great, same for the U.S. and around the world, but what’s all this about agriculture being a major contributor to climate change?

Me: Well, first of all, you don’t have to believe Mr. Kerry. He also supported and pronounced predictions that the Arctic would be ice free by the summer of 2014, which of course turned out not to be the case. Even my flight map on a recent trip reflected this:

He could have chosen a much lower number (instead of his one-third contributing figure), but his remarks reflect an unfamiliarity with agriculture such that he apparently views it as just another industry to be regulated. First, Mr. Kerry could have disclosed that even the United Nations has stated that over 50% of emissions attributed to agriculture involved activities that happen after the crops leave the farm, in other words, packaging, transportation, and waste management. However, he evidently didn’t care about this distinction, perhaps just that the headlines read: “Agriculture. One-Third Contributor. Climate Change.”

Mr. Kerry could have focused his comments on U.S. agriculture. Agricultural emissions are only really estimates, some would say guesses, anyway as sensors are not located around farms and ranches to collect emission data.

The International Energy Agency puts U.S. agricultural greenhouse gas emissions only at 8%. The U.S. Environmental Protection Agency (EPA) estimates that agriculture accounts for only 10.6% of emissions. In North Carolina, agriculture is estimated to account for only 9% of total emissions and which have been decreasing since 2005. These statistics must be taken with a grain of salt as, according to the North Carolina Department of Environmental Quality, it is “particularly challenging” to measure and quantify emissions associated with working agricultural lands and this sector has a “larger amount of uncertainty. “

Farmer: So, emissions as a whole must be rising in the United States to get everyone so riled up.

Me: Well, actually, greenhouse gas emissions in the United States decreased 18% from 2005 to 2018. Interestingly, the North Carolina governor in 2018 issued Executive Order 80 which was aimed at climate related things and stated as a goal reducing greenhouse emissions by 40% from their 2005 levels by the year 2025. Well, in fact greenhouse gas emissions in North Carolina have been determined to be down 38% from 2005 to 2020. This is close enough to the governor’s stated goal for the state that even the most ardent global warming activist may consider chilling out a bit, but we will see.

Farmer: So, let me get this straight. Our country’s emissions have dropped by almost 20% in the past couple of decades and keep dropping, with a 38% drop in North Carolina, agriculture in North Carolina only contributes (maybe) 9% to total emissions in the state, the studies done in the past 20 or so years conclude that significant climate change is really not occurring in North Carolina and we farmers and ranchers nonetheless may be subject to a growing array of new climate-related regulations which will decrease our ability to survive?

Me: Maybe. That is the scenario this article is attempting to address at the front end. It is so arbitrary that it depends on the political party in power. Right now, the U.S. Farm Bill is still being debated in Congress. The Democrats reportedly will vote in favor of the new bill if it preserves a great deal of funding for climate-related initiatives. The Republicans denounce the farm bill as too much “Green New Deal” and not enough agriculture.

And, get this — the USDA recently published its 2022–2026 Strategic Plan. What is it’s #1 strategic goal? Is it to Provide All Americans Safe, Nutritious Food? No, out of its six strategic goals, that is down the list at #4. Instead, the USDA’s new #1 goal is to “Combat Climate Change.” So, you can see that one political party currently in executive power is willing to place the climate change agenda ahead of the rights of the American consumer to safe, nutritious food.

Hopefully those who are supposed to be supporting North Carolina agriculture, the agencies, the agents, the university consultants and others, will choose to support ag instead of just gradually going along with the climate change proponents and raising the temperature of the water in the pot. However, the USDA already has a list of dozens of “Climate-Smart Agriculture Mitigation Activities” and other countries already have imposed severe climate-related laws on farmers — more on that a bit later.

Farmer: Will the North Carolina State Climate Office be of help to us farmers?

Me: Hopefully. It already works with agriculture by way of forecasts and offering other climate related tools, but it currently is a proponent of the climate change narrative and we will just need to wait to see if it in the future takes the side of climate over agriculture if the time comes for the imposition of costly climate related regulations. Realizing that some will say that there are no sides and that a climate conscious government and agriculture can work together for the good of the planet, unfortunately there are sides which for understandable reasons have developed in other countries and which are developing in the U.S.

Farmer: Why do you say that?

Me: Well, the State Climate Office has more recently taken the position that agriculture is a “ … a pretty big contributor globally” to climate change. The current Director has stated that the climate “crisis” also involves a moral imperative and a moral obligation.

The State Climate Office uses images to show sources of greenhouse emissions. In one Climate Office presentation, next to a photo reflecting a scene of burning hot heavy industry giving off fiery emissions, the Office places an image of cattle grazing in a field as another emission source needing to be addressed.

More generally, the Office’s current Director has been quoted that, “Climate change is here, it’s now and it’s hitting us hard from all sides.”

How about you, has the climate been hitting you hard from all sides recently?

Farmer: Well, not that I can recall, but diesel prices have skyrocketed the past three years and that’s been a hard hit. What I also don’t get is that every time there is a weather event like a hurricane, we always hear on the news some expert saying that it is due to climate change, is that true?

Me: We all now hear these “this is the new normal” and “this is the face of climate change” type statements after a weather event. But, for example, as I mentioned before, it is clear that hurricanes were more frequent and intense in the early part of the last century than they are now.

Farmer: I also keep hearing from the folks with the state that minimum temperatures have risen significantly because of climate change and this will impact agriculture, what about this?

Me: Yeah, I know what you mean. This seems to be a common comment from climate change proponents. But beyond that, what’s more important is that minimum temperatures are not rising in a significant, enduring and unprecedented way in North Carolina.

Farmer: Explain to me why.

Me: Let’s go back to the State Climate Office’s 2002 report on our state’s climate. It concluded, “… there was no widespread pattern showing increasing minimum temperatures across the state.” Interestingly, while the report from 2015 (the one that was taken down from the State Climate Office website) noted a rise in minimum temperatures, this rise was found only in urban areas and not found in rural areas. The authors of the report thought this was due to urban development and made a point of noting that it was not due to global warming.

The 2020 climate report did not dispute the findings of the State Climate Office that the rise in minimum temperatures was only found in urban areas and apparently did not even attempt to study whether this was found in rural areas. The report also did not compare 30-year time periods from early in the last century to the most recent 30-year time period, although it did acknowledge that abnormally high minimum temperature periods had existed in the first part of the last century. When I looked at the subject in my most recent study, Wake County minimum temperatures were higher in the 30-year period from 1913–1942 than the most recent 30 years.

Lastly, the study involving the six Primary Local Climatological Sites in North Carolina showed that only one of the six stations had average minimum temperatures for the last 30 years which were higher than the average and with no corresponding rise in a 30-year time period before 1950.

Farmer: We’re also told that we can expect there to be more droughts, what about that?

Me: There hasn’t been a drought of significance in North Carolina since 2007–8. See here.

Farmer: Recently, I have been hearing about “flash droughts” we are having.

Me: A “flash drought” is what you and I would call a dry spell. It’s a catchy term that has come into use in recent years and even now is referenced by the USDA. If real droughts aren’t occurring, then, frankly, those who are raising alarms about climate change have come up with a related calamity-type term and attribute ominous significance to it. The 2002, 2015 and 2020 North Carolina studies did not consider the subject of “flash” droughts worthy of investigation or discussion and the term “flash drought” was not even used. The 2020 study concluded that droughts are a natural part of North Carolina’s climate and did not find any increase in droughts over history. Lastly, if “flash droughts” were such scientifically established phenomena, then there would be an accepted definition of what they are. However, a group of scientists, including two from NOAA, tried to determine what a “flash drought” was and in a published study found that there are at least 29 different definitions in the scientific literature.

Farmer: I think I’ll stick with “dry spell.”

Me: One last thought on the subject of droughts. The high temperatures, winds and drought conditions during the great dust bowl era of the mid-1930’s resulted in the only mass migration of people in the United States due to climatic conditions. The great dust bowl occurred during an era before it could be blamed on man-made climate change. There is much written on the horrible climate and weather conditions of the 1920’s through the 1940’s in many parts of the country, for example this article here, “The 1930’s — Decade of Extreme Weather.”

This is the face of despair, with serious climatic conditions as a cause. I grew up with the children of these farming families turned migrants who made their way to the Central Valley of California and were derisively referred to as “Okies” since many of them came from Oklahoma. These hard-working, desperate folks would have welcomed just a few dry spells or “flash droughts.” Frankly, the use of the phrase “flash drought” by climate activists is a slight to their memory and to their story. Fortunately, North Carolina has not had a significant drought for over 15 years.

Farmer: You mentioned actions against farmers by other countries in the name of fighting climate change — what can you tell me about that?

Me: Let’s just review several of them. And, keep in mind, there likely are those in government who would be willing to enact the similar programs on U.S. agriculture if they could. A representative example is this quote from a member of the United States House of Representatives Agriculture Committee. “We are going to have to talk about cutting emissions from farms and changing some of the practices.”

Sri Lanka

To great fanfare and support by the international climate community, the government of Sri Lanka banned the use of chemical fertilizers in 2021. Over 90% of Sri Lanka’s farmers had used chemical fertilizers before they were banned. Sri Lanka’s anti-modern fertilizer government had the support of the European Union and World Bank, with them pledging $3 billion to help ease the transition.

After they were banned, 85% of farmers experienced crop losses, rice production fell 20% and prices skyrocketed 50 percent in just six months. Sri Lanka had to import $450 million worth of rice despite having been self-sufficient in the grain just months earlier. The price of carrots and tomatoes rose five-fold. One-third of Sri Lanka’s farmlands were dormant in 2021 due to the fertilizer ban.

The damage to the country’s tea crop was immense. Tea production had generated $1.3 billion in exports annually and paid for 71% of the nation’s food imports before 2021. Then, tea production and exports crashed between November 2021 and February 2022.

The government of Sri Lanka subsequently fell. Protesters breached the official residences of Sri Lanka’s Prime Minister and President, who fled. The nation went bankrupt and defaulted on its debt payments. Millions are struggling to purchase food, medicine and fuel. Inflation rose to over 50% and food prices rose by 80% with a half-million people falling into poverty. See here for more detail and the source for this description.

Netherlands

The Netherlands is the largest exporter of meat in Europe and the second largest exporter of food overall by economic value in the world, after the United States. By the Dutch government’s own estimates, 11,200 farms out of the roughly 35,000 dedicated to dairy and livestock would have to close under its policies, 17,600 farmers would have to reduce livestock, and total livestock would need to be reduced by one-half to one-third. The Dutch government has demanded that animal farming stop entirely in many places. See reference for this information and further detail here.

Canada

Canada is seeking a 30% reduction in nitrogen pollution by 2030. While the Canadian government says it is not mandating fertilizer use reductions, only pollution reductions, experts agree that such a radical pollution decline in such a short period will only be possible through the government enforcing reduced fertilizer use, and thus reduced food production. The cost to farmers would be between $10 billion and $48 billion. The total value of lost production is estimated to grow to $10.4 billion per year by 2030. See here

Germany

The German government in 2019 enacted policies requiring a 20% reduction in the use of fertilizers and pesticides as part of its “agriculture reform package.” Subsequently, fertilizer prices rose 300%. See, here. More recently, the government has raised its “carbon” tax on diesel fuel a full 50%, resulting in a dramatic increase in diesel’s price.

Ireland

Earlier this year, the Irish government issued a memorandum which considered the slaughter of 200,000 cows to help it meet its climate targets.

European Union

The “Nature Restoration Law” was adopted by the European Union Parliament. The law sets binding targets for 20 per cent of the EU’s territory to be “restored to nature” by 2030. Critics insist it will hit farmers hard, encroaching on their land and could lead to the liquidation of millions of acres of agricultural land.

Further, the EU’s “Farm to Fork Strategy” calls for 10% of agricultural land to be set aside for non-farming use and at least 25% of EU farms should be organic.

The EU also imposed a 20% reduction in fertilizer use and a 50% reduction in pesticide use by 2030. While the EU recently paused these regulations, it only did so until in view of upcoming elections and promised future regulations, which would be more “mature,” without elaborating on this ambiguous adjective.

As far as the United States goes, it’s not a question of whether there are legislators who support these types of policies, right now it is just a question of timing and how many, which is why people need information such as is discussed in this article and why those whose jobs it is to support agriculture at some point take a strong stand to protect it, rather than urging it to gradually, drip by drip, accept various climate mitigation strategies until it’s too late to be economically viable. As one department head in North Carolina’s ag world said, “sustainability” in North Carolina’s agriculture these days really just means staying in business.

The threats to viability in North Carolina agriculture are great, primarily including the reduction in farmland due to population growth, according to the state’s Commissioner of Agriculture. These various threats also are starkly and personally reflected in a recent paper which reported that the rate of suicide among farmers is 3.5 times that of the general population. Adding all of the various climate-related regulations that are on the government’s and climate activists’ wish list will only serve to exacerbate this unfortunate situation.

Poland

Farmers recently descended in large numbers on the country’s center of government, calling for changes to restrictions placed on them by government regulations on agriculture related to climate change, among other issues. Some protesters burned a coffin bearing a sign that read “Farmer, lived 20 years, killed by the Green Deal” in the street in front of the Prime Minister’s palace.

New Zealand

New Zealand’s government in 2022 proposed taxing the gasses that farm animals make from burping and peeing as part of a plan to tackle climate change. The government previously in 2003 had introduced similar legislation, which became known as the “fart” tax, but which the government stressed should really be referred to as a “burp” tax since most emissions come from animal burps, but it did not become law. The 2022 legislation is still pending, with farmers complaining about its vagueness, impracticality and lack of necessity.

There also are attempts by some to develop devices which slip over a cow’s face in order to capture cow burps and transform the emissions from the burp into something thought to be less harmful. However, anyone who has spent time with cattle and seen them rubbing an itch on a tree or fence post can explain why this may just not be feasible.

The EPA also is attributing emissions to buffalos, “mules, asses” and camels, so it will be interesting to see what kind of face (snout?) coverings might be developed for them. It also would be something to see someone trying to place them on a herd of wild bison.

Farmer: How about here in the U.S.? Whatever happened to the Green New Deal we heard about a few years ago.

Me: In 2019 Congresswoman Alexandria Ocasio-Cortez somewhat famously came out with a bill referred to as the “Green New Deal.” Among other things, her fact sheet in support of the bill stated, “We set a goal to get to net-zero, rather than zero emissions, in 10 years because we aren’t sure that we’ll be able to fully get rid of farting cows and airplanes that fast.”

Farmer: Well, I haven’t been able to afford to fly for a while, but I know that if they want to get rid of farting cows, then that means I have to get rid of all my cattle.

Farmer: So, what kinds of issues may farmers have to face in the United States?

Me: It’s already starting.

On the state level, similar to the European Union’s Nature Restoration Law, California’s Governor has issued an Executive Order that 30% of all land in the state is to be “conserved” By 2030.

North Carolina’s governor recently issued Executive Order 305 which calls for the restoration or reforesting of 1,000,000 new acres of forest and wetlands and the conservation of 1,000,000 new acres of natural lands with a focus on wetlands. The subsequent North Carolina Priority Climate Action Plan created by the Department of Environmental Quality (NCDEQ), endorsed the reforesting of some proportion of “less productive” agricultural land and also supported the “rewetting” of peatlands previously drained for agricultural use.

U.S. agriculture now will not only have to deal with the USDA, but also the EPA, who just recently created the “Office of Agriculture and Rural Affairs” to help deliver “climate solutions.” The head of the EPA somewhat ominously stated that the EPA and USDA would work together to “model the type of behavior that we want to see …” Perhaps an example of this are recent remarks from the head of the USDA to the effect that “non-prime” farmland be converted to production of renewable energy. The USDA also has recently published a “Climate-Smart Agriculture and Forestry Mitigation Activities List.”

Farmer: Before we get into this list, can we first discuss this war on livestock in the United States?

Me: It’s kind of ironic if you take a step back and think about it. We used to have tens of millions of buffalo roaming the country, who basically have now been replaced in numbers by cattle. Yes, they burp, fart, poop and pee, but animals in grasslands are how nature has built soil for hundreds of thousands of years.

Farmer: Do cows really cause climate change?

Me: Well, if you were to accept what the EPA has to say, all of animal agriculture contributes only 3.9% of total U.S. greenhouse gas emissions. Even at that, this is a gross number as the sequestration of carbon (including CH4 — methane) in the agricultural sector is not deducted from its emission data and instead is taken into account in another sector, see here at 2–28. Indeed, scientists have concluded that grasslands managed for livestock actually are a net sink of carbon at a global level, sequestering more than is released. If the amount of carbon which the EPA reports as sequestered by cropland were to be deducted from agriculture’s estimated emissions, then the gashouse emissions percentage attributed to agriculture would be significantly reduced, see here at 6–6. Another study concluded “there is no scientific evidence, whatsoever, that domestic livestock could represent a risk for the Earth’s climate.” Also, while methane emissions in the U.S. have been reported to have increased in past decade, the number of cattle has decreased, so a reported rise in methane levels should not be caused by cattle. See, here. Are there studies with different conclusions? Of course, but my point is that those involved with North Carolina agriculture should be building the evidence to support, not derail, its livestock industry. For example, it should be noted that methane emissions have not risen in North Carolina since 2005 and they also have been steadily decreasing in the whole of the United States since 1990.

Farmer: So, even with this information, there are still people who want us to get out of the livestock business?

Me: Yes. A 2021 Time magazine article was titled, “Cows Are the New Coal.” There are U.S. policy advisors who advocate for government intervention in reducing livestock and meat consumption and adopting alternatives to meat. It’s also interesting to keep in mind that 75% of North Carolina’s value of agricultural production is livestock and the other 25% is crops.

Farmer: What do the powers that be in North Carolina think about this attack on the livestock industry?

Me: The North Carolina Department of Agriculture’s Commissioner of Agriculture sent a January 29, 2024 letter, along with several other states’ heads of agriculture, to six large financial institutions, expressing concern that the banks had made commitments to the “Net Zero Banking Alliance,” which is associated with the United Nations Environment Programme (the same outfit involved in Sri Lanka’s food and financial disaster). The letter pointed out that “implementing these commitments would have severe consequences for American farmers — including cutting America’s beef and livestock consumption in half, switching to inefficient electric farm equipment, and moving away from the nitrogen fertilizer necessary for American agriculture to thrive.” Subsequently, at least two of the largest financial companies have withdrawn from their commitment.

As for the legislature and governor, it just depends on who is in office.

Farmer: Even if you assume their beliefs about cattle emissions, do they ever weigh the benefits?

Me: It has been explained here that cattle upcycle inedible cellulose material like grass and convert it into nutrient-dense beef and more than a hundred life enriching byproducts, all the while protecting wildlife habitat, reducing the spread of wildfires as they consume brush, aerate the soil with their hooves, and are part of a circular methane cycle. As a by-product of consuming cellulose, cattle do belch out methane, returning that carbon sequestered by plants back into the atmosphere but only temporarily as the methane is broken down after about 10 years and converted back to CO2 as part of a biogenic cycle, meaning that the carbon is the same carbon that was in the air prior to being consumed by an animal. In other words, it is recycled carbon per this analysis.

Farmer: What alternative food source do climate change activists against meat support?

Me: Insects. And weeds.

The World Economic Forum claims “eating insects could reduce climate change” since “our consumption of animal protein is the source of greenhouses gas.” The same organization also has said “we need to start nurturing — and eating — weeds,” which “can be nutritious and tasty, if we know which ones to pick.”

Farmer: But this is just from some type of global think tank and not supported in the U.S., right?

Me: Well, the USDA recently awarded a six-figure grant to a company to study raising crickets on feed made up material from city garbage dumps. USDA’s grant listing contains criticisms of traditional livestock practices, “Conventional protein production poses a substantial strain on the ecosystem, requiring unsustainable quantities of water, land, and feed as inputs.” The grant description also calls “conventional” farming a “significant source of greenhouse gas emissions.”

Me: Oh, I forgot to ask you — do you have dogs?

Farmer: Yeah, why do you ask? I don’t know too many farmers without dogs running around.

Me: Well, they also want your dogs as well. A study at a well-known land-grant state university estimated the carbon pawprint of dogs and recommends that we don’t own them because they contribute to global warming. The author recommends having birds or hamsters instead. The Canadian Broadcasting Company even interviewed a climate physicist and environmental epidemiologist with the Imperial College in London and noted, “Pets are methane producing, meat eating monsters using up earth’s finite resources, says climate physicist Robbie Parks.” There also was a 2009 book written by sustainable living specialists in New Zealand who assert that a medium-sized dog has an ecological pawprint twice that of a Toyota Landcruiser. The book is actually titled, Time to Eat the Dog?: The Real Guide to Sustainable Living and is available on Amazon.

Farmer: Scary stuff.

Me: Also, at the most recent United Nations conference, the United States, along with other countries, signed a pledge to keep agriculture in the crosshairs in future climate meetings, via the “UAE Declaration on Sustainable Agriculture, Resilient Food Systems, and Climate Action,” which commits the countries to integrate food into their climate plans by 2025. One example of what is being pushed for is the organization Plant Based Treaty, which claims we are “eating our way to the planetary brink” and that the global food system is the largest contributor to greenhouse gas emissions, even greater than all forms of transportation. The aim of this organization is to is to eventually have anti-agriculture regulations made mandatory by national governmental laws and trade treaties.

Agriculture also has now gone mainstream viral with the climate activists who earlier this year threw soup at the Mona Lisa hanging in the Louvre in Paris. The environmental justice group which claimed responsibility for the attack, Riposte Alimentaire, describes itself as a collective dedicated to advocating for action on climate change and sustainable agriculture, and wants the government to take over all means of food production.

Let’s look at some of the ag practices that the USDA and others are suggesting or requiring in the name of saving the planet from climate change/global boiling.

First, there is the move to electrify farm equipment. Replacement of the internal combustion engine is now on the USDA’s list.

Farmer: It’s not unusual during a harvest to be using our tractors around the clock in order to get the crop in. There is no way that an electric tractor or even a pick-up will hold a charge long enough to do that. Plus, electric trucks will only add to the cost of transportation since the battery takes up so much space and is so heavy (roads have weight restrictions) that it will take at least double the number of trips. Plus, I just heard of a recent study which, noting the much heavier weight of electric vehicles, found that EVs actually produce much more potentially harmful particulate emissions from their tires than gas powered vehicles, which are lighter and don’t produce much in the way of tailpipe emissions these days.

For ranchers in really cold places like the mid-west, the EVs just don’t cut it in severe below freezing temps. And, as far as a pick-up goes, to get a reasonable towing and driving range, you need to buy the loaded version, which is about $90,000, plus it takes time and costs more than you think to charge. I came across this test report in MotorTrend about a popular truck, the electric Ford F-150, and it’s not encouraging.

Me: What would happen if you stopped using nitrogen-based fertilizers?

Farmer: Well, just look what happened in Sri Lanka. Also, we deserve some credit. Just think about how we use fertilizers. Farmers have to pay for fertilizer, nitrogen fertilizer being particularly expensive. So, farmers have every incentive to maximize nitrogen use efficiency (the fraction of nitrogen from fertilizer that is taken up by a crop). The lower the crop uptake of nitrogen, the greater will be the potential losses of nitrogen to air and water and the larger the fraction of fertilizer expenditures that would be wasted.

Me: I’ve also seen a recent paper by a group of international scientists which reports that “Proposals to place harsh restrictions on nitrous oxide emissions because of warming fears are not justified … . Restrictions would cause serious harm; for example, by jeopardizing world food supplies.”

Why not just use manure?

Farmer: Practicality, supply, inability to measure it and uncertainty as to what nutrients are being applied.

Me: No-till farming has been suggested.

Farmer: So, I will refer you to a good article from Iowa about plowing. The bottom line is that the decision should be left up to the farmer. Some farmers do a modified form of no-till called strip tilling which helps with soil moisture retention. While no-till will help with moisture retention, it also can increase costs in that special equipment is needed to plant seeds into the harder soil, with many areas of soil being more compacted than in past times due to heavier farm equipment being used. Plowing also can help prevent water run-off and it’s an effective way to control weeds instead of using herbicides.

Me: What about planting cover crops?

Farmer: I don’t get the connection with global warming, but in any event, cover crops can keep down weeds and help with soil moisture retention, but they become kind of another whole crop to expend energy and money on, and they can compete for water and nutrients. I actually was offered a financial incentive to plant cover crops, but it didn’t make economic sense, so I didn’t do it.

Me: A buffer strip also is on the USDA’s list, how would that impact you?

Farmer: It basically would just take some of my land away from our farm by creating a buffer strip around the land with some type of cover crop. My water and soil don’t go anywhere, so I don’t see the need for this.

Me: The USDA’s list also includes converting cropland to grass-based agriculture. What do you think about that?

Farmer: Well, this is the USDA recommending that I stop growing all of my crops and just grow grass, legumes or “forb.” I had to look up forb; it’s basically something like a dandelion. My crops feed people. I think this is just calling for unproductive, grassy fields.

Me: Are you open to monetary incentive programs?

Farmer: Well, it sure is better than what is going on in other countries with land actually being taken away and other restrictions being put in place. But the problem with incentives is that they usually aren’t enough to cover all the costs and they can be taken away next year. Practices that make economic sense are the best way to go, and also practices that actually are needed. For example, I remember when we had rivers catching fire, smog in the air and contaminated soils. But the environmental regulations that were put in place the past few decades have left the environment cleaner than it has been in 50 years. I mean, when was the last time you heard of people lying down in the road or throwing stuff at artwork in a protest over smog or clean water? It seems now that all that has pretty much been taken care of, the activists and regulators have moved onto this climate change thing. We’ve been warned for over three decades now that due to a changing climate, agriculture was going to suffer with farms going out of business. While farms are under pressure from economic factors and reduced land, they have not been going away because of some new embedded trend in our weather each year.

Me: Why not just go “organic?”

Farmer: While I think most of us support the idea of organic farming, virtually all farmers can’t afford to go organic to the extent that no chemicals of any kind are used. It can be profitable for small farmers in niche markets and some larger growers have organic divisions, although typically supported by a conventional side. In the larger picture, attempting to move from widespread conventional farming to organic, free-range farming would require vastly more land and destroy natural habitat.

Me: I’ll add to that by noting conventional agriculture is used on 99 percent of U.S. cropland and is responsible for significant environmental improvements to farming. The total amount of pesticides applied to U.S. crops declined 18% between 1980 and 2008 and is today 80 percent lower than their 1972 peak. Total fertilizer use in the U.S. peaked in 1981 and hasn’t risen since, despite an increase in total crop production of 44 percent, according to the EPA. Also, there is a recent study concluding that organic animal farming has just as many emissions as conventional farming.

Me: There also is a proposed Securities Exchange Commission (SEC) rule, “The Enhancement and Standardization of Climate-Related Disclosures for Investors,” which, through so-called Scope 3 emissions, would require farmers, regardless of size, to track and report data regarding “indirect” emissions from a vague array of sources to the companies with which they work. The Scope 3 emissions reporting requirement could impact most farms since a majority of agricultural products are used or sold by a publicly traded company. But 98% of all farms in the U.S. are independent and most family operations do not have the resources to track and report the emissions data necessary to meet the disclosure requirements. While the SEC decided in this election year not yet to include agriculture in this requirement, it will remain under pressure from climate activists and politicians in solidarity to re-visit this issue in the future. California, though, actually has already enacted a similar law requiring the same information gathering and disclosures by agricultural interests, SB-253, which is in the process of being implemented.

Also, if you were required to track any sort of emission from your farm that could somehow contribute to global warming, you would have to be holding sensors in front your and your family’s mouths and noses throughout the day.

Farmer: What’s the last point you made?

Me: There is a recent study which concludes that just humans breathing throughout a typical day contributes to climate change.

Farmer: Oh boy.

Me: Maybe you can outfit your family with those masks being designed for cows to wear. Oh, and don’t forget to include your dogs as well. Unfortunately though, there are some whose ideal scenario is a deindustrialized world with fewer creatures, so it’s important to take all of this stuff seriously.

Me: What about setting aside part of your farm for solar panels?

Farmer: I’m fine with putting panels on top of our home or even barn as a form of renewable energy and if it will help bring our electrical bill down, but I really don’t want the eyesore of rows and rows of panels. In any event, it really isn’t possible unless it’s to scale, that is, unless I give up a large portion of my acreage, and I mean give it up. I might as well let a small subdivision come in.

Me: What about something like biodigesters, machines that take the methane out of manure and allow the manure to be re-used out on the field?

Farmer: Wait a minute! I thought there are those who think it would be great idea if we all went organic, and now I am expected to use machinery to scoop up all our manure, put it in a machine, then use more machinery and power to spread it out over what? If you’re a big, vertical operation, then I suppose it could be used for nutrient supplementation of whatever is being grown for feed, but I would just be returning it to my grazing fields, where it was in the first place.

Me: Ok, time to wrap things up, any final words?

Farmer: I hope that people realize how important agriculture is and that we are feeding more and more people, while continually using less land and fewer resources. We always are personally incentivized to use the latest, most advanced and most cost-effective technologies and will continue to do so. I realize that there are some very smart people who truly believe in, whatever you want to call it, global warming, climate change, global boiling, but it is indisputable that there are a lot of politics and money involved. There also are some very smart people who are pointing out either that while it may be warming a little recently, we can easily adapt, or that it is not that significant and certainly not unprecedented. Plus, we were being told over 30 years ago that the “science was settled” on climate change and its causes, so why now start pointing the finger at ag? Control of the food supply is a powerful thing so I’m not surprised that politics are involved.

I hope that those folks whose job it is to support agriculture in North Carolina, and others as well, are willing to side with us against unnecessary and costly regulations, even if it means going against the grain of peer, academic and financial pressure, and not gradually lead us into a life of regulation and restrictions that gradually will, one by one, lead us to go out of business and threaten our food supply.

By Tom Packer, longtime backyard farmer in North Carolina and Northern California. He also has an advanced certification in gardening, is Past-President of one of the oldest garden clubs in North Carolina and is a Board member of a foundation which supports agricultural research and teaching activities in the Tar Heel state. He obtained his B.A. and J.D. degrees from the University of California. All this educational article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated. This article originally was published on March 20, 2024.

This is the annual update to the article, A GARDENER’S LOOK AT THE CLIMATE IN NORTH CAROLINA BACKYARDS: WAKE COUNTY, PIEDMONT REGION — 2020. The 2021 update can be found here and the 2022 update here. While the article’s background, history of climate change studies in North Carolina and how gardeners can themselves access online climate tools remain, climatic records and observations have been updated to include 2023 data.

The research-based conclusions remain the same: All published North Carolina climate change studies have not found significant, enduring and unprecedented changes in the state’s climate to date, even though the most recent one claims some climate change is taking place and predicts changes in the future (discussed in more detail below). The trend of no unusual increase in severe weather events continued, hurricanes continued their decades-old pattern of decreasing in frequency and intensity, and climatic factors important to gardeners such as average Spring and Fall freeze dates, soil temperature, humidity and growing seasons remain within a historically normal range.

Gardeners increasingly are being provided with information on climate change in North Carolina. However, a couple of additional perspectives are helpful: (1) input from average home gardeners about what climate and weather issues matter most to them and (2) an examination of the local climate and weather where we actually live. Presenters have warned gardeners of changes in the climate involving rising temperatures, extreme rains, more frequent and powerful hurricanes and the specter of drought. This has led to advice which at times is regressive such as not to use modern, scientifically developed fertilizers, to replace our lawns, stop using power tools, in addition to watching out for spiders with more powerful venom and new insects being attracted to warming soils.

This article is written for gardeners by a fellow home gardener and is meant to empower gardeners to assess and evaluate the climate in their own location. The following information will give gardeners the tools to look behind the figures if they wish to do so. These days, the information by which many observations and conclusions about the weather can be made is at our fingertips and there is no reason that gardeners cannot also be citizen scientists and figure a good number of things out for themselves.

For years I had been your average home gardener but then received intensive horticultural training and education through a state university program which emphasized making decisions, as well as giving and interpreting advice, grounded on research-based information. I was preparing a presentation on Fall gardening and managed to figure out the average first Fall and last Spring freeze dates in my hometown of Raleigh, Wake County, North Carolina. Through this process and interactions with representatives of various climate agencies, I had a peek into how climatological calculations and conclusions were made and learned that as gardeners we should always verify what we are being told by climate and weather authorities and support our decisions with our own research whenever possible.

When we are told that our climate has changed and that the change is (1) significant, (2) enduring and (3) unprecedented, we want to know if real, transparent facts exist where we actually live to support these conclusions. So, this article is an examination of whether there exists in Wake County, North Carolina, and the surrounding Piedmont region, significant, enduring and unprecedented climatological trends. It also examines some statewide issues such as drought and hurricanes, and also examines climate issues that are of particular interest to gardeners.

WAKE COUNTY

Wake County is in the middle of the state of North Carolina and is where the state capital of Raleigh sits.

North Carolina is known to be divided into three regions, the Mountains in the West, the Piedmont region in the middle and then the Coastal area to the East. Wake County is in the Piedmont region and the weather observations reported later will be applicable to many of the surrounding areas in the Piedmont, which generally has a similar topography and climate.

HISTORY OF CLIMATE CHANGE STUDIES IN NORTH CAROLINA

First, a brief history of climate change research in North Carolina to provide a background before drilling down to the conditions in Wake County. There have been three major climate change studies in the past couple of decades.

2002 Climate Analysis

Two leaders of the State Climate Office of North Carolina (SCONC), published a 2002 paper in Environment International titled Analysis of Climate Trends in North Carolina (1949–1998).¹ This study started off by noting that North Carolina has one of the most complex climates in the country and that most of the climate trends found were local, not statewide. The study found on a statewide basis that while temperatures in the last 10 years of the study were warmer than usual, they were not warmer than the temperatures experienced in the 1950’s. They did find that the dates between last Spring freeze and first Fall freeze had become longer and that precipitation had increased during the study period for the Fall and Winter seasons but had decreased during the Summer and remained the same for Spring. Maximum temperatures had remained fairly constant and there was no widespread pattern showing increasing minimum temperatures across the state.

2015 Climate Change in North Carolina Report

This report, by the State Climate Office of North Carolina, looked at a much longer time period, investigating records back to the late 1800’s.² The report found no warming trend in the 113-year study period starting from 1895. While there was some warming since the mid-1970’s, it was found to be not unprecedented and similar to the warming observed from 1910–1950. The 2015 SCONC report stated that in North Carolina there is “no meaningful trend that is associated with global warming.”

Interestingly, while the report noted a rise in minimum temperatures, this was only in urban areas and was not found in rural areas. The report concluded that possibly this was due to urban development, but it was not due to global warming. The report also found no meaningful trends in precipitation and that there had not been more frequent or longer droughts in modern times.

The SCONC summed up its view on climate change in 2015 by pointing out that it also had analyzed dozens of other temperature data “(including seasonal patterns, days with extreme high and low temperatures, a variety of temperature thresholds, degree days, growing season data, frost data), and one common thread joined them all: “… the trends are generally flat …” The State Climate Office concluded that, “… local climate variability is so high in North Carolina that significant trends are difficult to deduce.”

This report likely remained on the State Climate Office of North Carolina website until 2016. While other content on this website goes back to 2012, the report can no longer be found and apparently was scrubbed from the site.

2020 Climate Study — North Carolina

This study was done in response to an order of the new Governor of North Carolina after his 2016 election and examined records through 2018.³ The above prior climate change studies were not mentioned in the study, nor is there any mention of the history of climate change studies in the state. The study addressed climate issues statewide, and also in the three main regions of the state, Western Mountains, the Piedmont and the Coastal Plain. The 2020 study’s conclusions as to climate trends for the entire state ambiguously included, as to average annual temperatures, that recent temperatures had increased statewide “about” 1° since 1895 (but nowhere in the report is the actual figure reported nor use of the adverb “about” defined). Further, it is not made clear whether this “about 1°” figure was compared to the existing average annual temperature in 1895 or compared to the average annual temperature for all the years since 1895.

Reference to the study’s charts and graphs does not assist with this issue because in a confounding twist, the 2020 study acknowledged that it used a different data set for all of its charts and graphics depicting temperatures and precipitation. Instead of using the data set from which it obtained its climate information (“NOAA’s National Centers for Environmental Information (NCEI) Climate Divisional Dataset (nClimDiv), version 2.”), it instead turned to a different data set for its charts and graphs, “NOAA NCEI’s Global Historical Climatology Network-Daily (GHCN-D), version 3.” The study did not explain how it used climate information from one dataset for its conclusions, but then used data from a different data set to illustrate these conclusions in its charts and graphs. As to the report’s use of the GHCN-D network for the content of its charts, however, NOAA acknowledges that two-thirds of the stations in this network record only precipitation. NOAA further states that anyone using this dataset should also cite a published article which found, according to NOAA, that, “In general, the stations providing daily observations were not managed to meet the desired standards for climate monitoring. Rather, the stations were deployed to meet the demands of agriculture, hydrology, weather forecasting, aviation, etc.”⁴ The 2020 study failed to cite this article.

In any event, given the specific scope of this article, that is, Wake County and the surrounding Piedmont area, reference will be made to the 2020 study’s conclusions regarding the Piedmont.

Of the 14 climate categories examined by this study related to the outdoor environment which could affect gardens, only two significant trends in the Piedmont were noted: (1) an increase in the average temperature from an undetermined time in the 1990s (while noting a similar increase in the 1930s — 1950s), and (2) days per year with minimum temperatures of 75° having increased since 2005 (while again noting a similar increase in the 1930s — 1950s).³

The study found very hot days (95° or higher) decreasing and the number of cold days (32° or lower) with no overall trend but increasing since 2014. The study found no long-term overall trends in the Piedmont in annual hottest temperatures, annual precipitation, extreme precipitation (days with 3 or more inches of rain), drought, and no overall historical trends in ice storms, tornadoes and thunderstorms. The study did reference an increase in annual coldest temperatures (based on an historical simulation method for an abbreviated period of 1970–2005) and decreasing snowfall but only as of 2007. The study did not address the history or future of hurricane impacts in the Piedmont region section of the report.

The 2020 study contains long range predictions which reach 60–80 years into the latter part of this century and therefore cannot be held to account by most of the existing population. The study projects significant changes in the Piedmont for each of the climate categories examined except for ice-storms and winter storms. However, the State Climate Office of North Carolina noted in its 2015 report that the climate models of the Intergovernmental Panel on Climate Change (“IPCC,” the lead United Nations body on climate change) had predicted warming over the past 50 years, but which had not occurred. The SCONC concluded that, “Unfortunately, the best global climate models we have do not do a good job of simulating the temperature and precipitation patterns over the southeastern US, and NC in particular.”²

2022 Average Temperature Study

Lastly, this author conducted a recent study involving the six geographically dispersed NOAA designated “Primary Local Climatological Data Stations” located in North Carolina, depicted in this graphic and which can be found here.⁵

The working hypothesis of this study was that the statements of scientific consensus of widespread global warming since the 1990’s would be reflected in unprecedented warming temperatures in these six Primary (meaning the highest quality and reliability) weather stations dispersed across the state. However, the results of the study revealed that in only three out of 18 instances, or 16%, were there rises in average temperatures that also did not have a corresponding rise in the average temperature being measured in a 30-year period starting in years prior to 1950. In other words, in 84% of the historical average temperatures at these weather stations, the temperatures were similar to those from the years pre-1950, meaning that generally any rise in average temperatures in the past 30 years is not unprecedented and is similar to the temperatures in the first few decades of the last century.

QUALITY AND RELIABILITY OF WEATHER STATIONS

The quality and reliability of the weather observation stations used when determining historical weather records in the 2020 climate change study should be examined so that the average gardener knows what kind of weather data is being relied upon. The 2020 study notes that it included and relied on the use of so-called “COOP” stations. There generally are three kinds of weather stations in descending order of quality, First Order (also known as Primary), Secondary and then COOP. First Order stations are those of the highest quality and reliability. They are monitored by professionals and reliably record hourly (and even sub-hourly) observations and are subject to additional and more rigorous quality checks than all other stations. As explained by a representative from the National Oceanic and Atmospheric Administration (“NOAA”): “When it comes to station quality, NOAA NCEI First Order stations are about as quality as it comes across the U.S. There are about 500 stations, mainly major airports, that are considered First Order sites, including KRDU (the Raleigh-Durham Airport). These sites often have more instrumentation and include more data when ordering official data from NCEI. Typically, these stations are a part of the Automated Surface Observation System (ASOS).” (“NCEI” = National Centers for Environmental Information).⁶

COOP stations (part of a Cooperative Observer Program), while more numerous, are monitored by volunteers (such as a homeowner with a station placed on his/her property) which can result in gaps in weather data records. While volunteer COOP observers can play an important role in providing weather information for forecasting and basic weather information, periods of missing weather recordings can preclude reliance on them in determining long term trends at a particular site.

While there exists a complex system of quality adjusting to take into consideration the vagaries of the COOP stations, nonetheless, none of the first three North Carolina climate change studies identified above discloses whether any minimum station quality qualifications and criteria were employed or whether any COOP stations were disqualified from use. There exists a First Order station in Wake County and the surrounding Piedmont area at the Raleigh Durham International Airport (RDU, also referred to in weather records as “KRDU”).

As gardeners, we like to get down to ground level, so let’s take an actual look at some local First Order and COOP stations in Wake County.

Here is an aerial shot of the installation that includes the First Order weather station at RDU (id #13722)⁷:

It has been in place since 1944 and is professionally managed and monitored, while recording hourly and sub-hourly observations. It has a 100% record of days recording and reporting the weather data discussed in this article. It presently records 95 weather parameters. Through NOAA’s ThreadEx program⁸, historical weather observations from 1887 by its predecessor station are included in the weather records provided.⁹ Examination of climatic records at weather stations in the ThreadEx program are an accepted, recognized method of assessing regional climate trends in the United States.¹⁰ Among all weather stations in the state, NOAA has designated RDU as one of only six “Primary Local Climatological Data Stations” for North Carolina.¹¹ These stations are regarded as “Primary” because of the extensive and manual quality control checks they are subject to, which other weather stations are not.¹¹

On the other hand, here is an image of a COOP weather station, (id #311535), located in Cary, North Carolina:

It is located in the front yard of a home in a residential neighborhood in Cary and with temperature observations beginning in just in 2001. It monitors three weather conditions, temperature, precipitation and snowfall. It is reported as missing 335 days of temperature observations.¹²

This is the Falls Lake Weather COOP station (id #312993). It is in the backyard of a home in a residential neighborhood.

A closer look reveals that it is a weather apparatus manufactured by the Davis instruments company which can be purchased online.

This station has been in use just since 2000 and is reported to have 505 missing days of temperature data in its average temperature reports.¹³

Here is the list of COOP stations in Wake County as provided by NOAA.¹⁴

Of the 14 COOP type weather stations listed in Wake County¹⁵, six have not been functional this century and two stopped functioning in 2010, 2012, one in 2022 and one in 2023. Of the remaining four stations, three stations have start dates since 2000 and one since 1993. So, for example, three stations with only 20 years of weather data, and missing hundreds of days of data, presumably were included in the 2020 climate change study to determine whether there have been climate changes since 1895. However, NOAA’s clear and unambiguous guidance is that when trying to determine what the climate is like during a period of time (what NOAA refers to as a “climate normal”) at least 30 years of weather observations should be used. Lastly, unlike the RDU First Order station in Wake County, none of these Wake County COOP stations have an uninterrupted report of complete climate records dating back to 1887.

NOAA’s use of at least 30 years of data is longstanding and based on the instructions of almost a century ago by the International Meteorological Organization to calculate climate normals by using 30-year periods. NOAA also relies on the general rule in statistics that at least 30 numbers are needed to obtain a reliable estimate of their mean or average.¹⁶ Additionally, the USDA has stated that at least 50–100 years of data of overall average temperatures are needed to assess changes in the climate.¹⁷

In other contexts, COOP stations only have been used if they meet minimum criteria. For example, in determining the annual minimum temperatures for their Plant Hardiness Zones, the United States Department of Agriculture (USDA) only used COOP stations if they had low temperature recordings at least 80% of the time in the cold months and for a minimum number of years.¹⁸

Using COOP stations with only a few recent years of incomplete observations, or even using older stations yet with significant incomplete records, dilutes the purity of the historical observations, particularly when examining a regional area such as the Piedmont and where higher quality, First Order weather stations with a long history of non-missing data exist.

While most studies and reports on weather and climate issues do not identify the individual weather stations involved, sometimes they are identified when reporting, for example, freeze dates in particular localities. If so, for the home gardener, the reporting history of any weather station can be searched at:

http://xmacis.rcc-acis.org

, which is supported by the NOAA Regional Climate Centers.¹⁹ Details of an individual station history such as maintenance, location and other items can be found by going to NOAA’s Historical Observing Metadata Repository at https://www.ncdc.noaa.gov/homr/# and entering the station id number or using the search function to find it.

EXAMINATION OF WEATHER DATA FROM FIRST ORDER WEATHER STATION RDU

The following will examine the historical weather data as reported and maintained by NOAA’s climate records for the weather station located at RDU and its NOAA selected predecessor station. Importantly, some of the categories are additional to those examined in prior climate change studies in order to be more directly relevant to gardeners, for example, humidity, average frost dates, growing season and soil temperature (using two stations other than RDU).

AVERAGE TEMPERATURE

The average temperature reported at RDU since 1887 is 60.15°.²⁰ This can be broken down by decade as follows:

1887–1893: 59.34°

1894–1903: 60.05°

1904–1913: 60.17°

1914–1923: 60.17°

1924–1933: 60.92°

1934–1943: 61.89°

1944–1953: 60.19°

1954–1963: 58.82°

1964–1973: 58.89°

1974–1983: 59.05°

1984–1993: 60.07°

1994–2003: 60.07°

2004–2013: 61.38°

2014–2023: 62.10°

A cool, warm, cool, warm trend through the decades can be seen by viewing these numbers and this chart:

The last three decades since 1994 the average temperature has been 61.18°, a 1.03° increase above the historical average. This can be compared to another warming period in the first half of the last century, namely the average temperature in the 30-year period from 1921–1950, which was 60.73° (.60° above the historical average), and which reflects just a .45° difference between these two 30-year periods. So, the average temperature for the past 30 years is not unprecedented in that a prior 30-year period from earlier last century also was more than half a degree warmer than the normal. The five warmest decades since 1887 have been (1) 2014–2023, (2) 2004–2013 (3) 1924–1933 (4) 1934–1943 and (5) 1944–1953.

Climate records from the 1950’s and before are deemed significant by the climatic research community as they occurred during a pre-industrial period reflective of natural (that is, non-manmade) climate conditions. As the lead author of the 2020 North Carolina Climate Study wrote, “Because industrial development was minimal until about midway through the 20th Century, the earlier record reflects mainly natural variability.”²¹

The 2020 North Carolina Climate Change study made references to this earlier warming period, but only compared the single 10-year time-period of 2009–2018 with another single decade, 1930–39. The report found a difference of “about 0.6°” but then moved on without further comparisons with other prior temperature phases in the 1800’s or 1900’s. However, as discussed above, NOAA requires that when comparing climate normals from periods of time to use at least 30-year, not 10-year, periods¹⁷, and it is the position of the lead author of the 2020 climate study that temperatures from the mid-20th century and before reflect non-manmade climate patterns to compare against more modern climate observations and patterns.²¹

AVERAGE MINIMUM TEMPERATURES

The average annual minimum temperature at RDU from 1887 to 2023 was 49.71°.²² The last 30 years since 1994 the average has been 50.36°. The average annual minimum temperature from 1913–1942 was 51.04°. The highest five decades of average annual minimum temperatures have been (1) 1933–1942, (2) 2014–2023 (3) 1923–1932 (4) 1913–1922 and (5) 1893–1902.

It is clear that the past 30 years of average minimum temperatures in in the Piedmont area are not unprecedented and are lower, or colder, than another 30-year period about century ago, from 1913–1942. Here is the chart reflecting these figures.

So, while minimum temperatures have been rising somewhat the past three decades, they were appreciably higher in the first few decades of the last century.

AVERAGE MAXIMUM TEMPERATURES

The average annual maximum temperature since 1887–2023 has been 70.59°.²³ The last 30 years since 1994 the average annual maximum temperature has been 72.01°, a 1.42° increase over the historical average. The average annual maximum temperature from 1928–1957 was 71.11°, a .55° increase over the average, thus again revealing that a 30-year period, or “climate normal,” from nearly 100 years ago also had higher than average maximum historical temperatures.

This is the related chart.

The above three averages show that for the last three decades, the average temperature has risen, but similar to a like period in the last century, the average minimum temperatures are almost a full degree colder than a similar period last century, while the average maximum temperatures have risen but a similar 30-year period in the mid-20th century also had average maximum temperatures higher than the historical average.

MINIMUM DAILY TEMPERATURES EQUAL TO OR ABOVE 75°

Before leaving the basic temperature observations, let’s take a look at the trend described by the 2020 climate change study of an increase in daily minimum temperatures equal to or greater than 75° since 2005, but with a well-above average spike in these types of days in the initial study period of 1900–1904. The study published a graph to illustrate this but notes that the figures used are from three sources, “NCICS (North Carolina Institute for Climate Studies), NOAA NCEI (National Centers for Environmental Education) and the State Climate Office of North Carolina” without explanation as to whose numbers were used, what numbers were used, whether they were combined, or in general how they were compiled.

In any event, the corresponding numbers from the First Order weather station in Wake County at RDU, shows that since 1887 there have been on average 2.96 days a year with the minimum temperature equal to or greater than 75°. There were 4.20 such days on average per year from 1914–1943 and 5.16 such days on average per year from 1994–2023.²⁴

As can be seen from the below graph, years with 10 or more days of 75° minimum temperatures (also referred by some presenters as “warm nights”) have been occurring for all of the weather reporting history, with a 30-year period pre-1950 of having an average of between four and five such days a year along with the last 30-years also having a similar, although slightly higher, average.

❗️

Before leaving this category, keep in mind that in 2015 the State Climate Office of North Carolina specifically found in its Climate Change in North Carolina report that while noting a trend of higher minimum temperatures (which it defined using the term “morning lows), this only was found in urban, not rural areas. The report concluded that this was a result of urbanization of North Carolina’s cities and “was not evidence of any impact from greenhouse gases and global warming to North Carolina’s climate.”² The 2020 study ignored this previously reported urban/rural issue involving a trend in higher minimum temperatures and did not address it.

RAIN

The average annual rainfall at RDU since 1887 is 44.66” a year.²⁵

The last 30 years have averaged 46.43” a year. The 30 years from 1887–1916 had an annual average of 46.66” a year. The year with highest amount of rainfall was 1936 with 64.22.”

Here is the corresponding chart.

The above shows that there has been no recent significant, enduring and unprecedented trend in average annual rainfall.

However, there have been claims about an increased incidence of “extreme’ rainfalls so let’s examine that issue.

“EXTREME” RAINFALL

Extreme rainfall is defined by the 2020 Climate Change report as when it rains three or more inches a day. This type of event could affect our gardens resulting in flooding, standing water, excessive moisture and plant trauma. Even though the 2020 report did not find any trends of significance involving extreme rainfall in the Piedmont region, let’s examine our rainfall patterns nonetheless.

1” RAINFALL EVENTS

The average number of days per year with 1 or more inches of rainfall since 1887 at RDU is 11.75.²⁶ In the last 30 years the average has been 11.93 days per year. From 1912–1941 the average was a similar 11.7 days with 22 days in 1936.

Here is the related chart.

2” RAINFALL EVENTS

The average number of days a year in which it rains 2” or more at RDU since 1887 is 2.21 days.²⁷ For the last 30 years the number is 2.53 days. The average for 1931–1960 was 2.56 days. So, no unprecedented extreme rainfalls of 2” or more per year in the last 30 years.

Here is the related chart.

3” OR MORE OF RAIN A DAY

It has been said that the number of days of “extreme” rain events of 3” or more a day had, and would, increase. Presenters referenced the heavy rainfall effects of Hurricane Matthew in 2016 (the effects of hurricanes to be discussed a bit later). While we all can recall the slow moving, swollen rivers after Matthew, according to the 2020 North Carolina Climate Change report³, no trend of an increasing number of extreme rain events has been found in the Piedmont. It can also be mentioned that the Matthew rainfall was the only extreme rainfall event in the Piedmont in 2016.

The average number of days a year since 1887 it has rained 3” or more is .54.²⁸ The past 30 years has seen an annual average of .80 such days. However, there was a 30-year period from 1931–1960 when the average was a similar .73 days. There have been only two such events the past five years. The 2020 NC Climate Change study found no trend in the Piedmont region relating to these types of extreme rains.

Here is the related chart.

SNOWFALL

The average annual snowfall reported at RDU since 1887 is 6.50”.²⁹ The average for the last 30 years is 5.08”. The average for the 30-year period from 1894–1923 was 5.65,” thus representing a previous 30-year period with below average annual snowfall.

NUMBER OF SNOW DAYS PER YEAR

The average number of days it snowed per year over recorded RDU history since 1887 is 3.61.³⁰ The average number of snow days per year for the past 30 years is 3.2.³⁰ The average number of snow days per year for the 30-year period of 1922–1951 was 3.33, thus reflecting a similar figure in an earlier time period in the last half of the 20th century.

Here is the related chart.

The above data reflects that no meaningful trends appear with respect to snow days.

HUMIDITY

Even though the State Climate Office of North Carolina predicts a more humid future for our state, a review of the relative humidity observations at RDU weather station reveals that there is no observable trend of increasing humidity. The average annual humidity readings in the past 30 years are in fact lower than the overall average. Climate change studies have not addressed whether humidity is increasing or not, perhaps because most weather stations in the COOP network do not report on humidity.

The average annual relative humidity at RDU since 1948 (the first-year reports on humidity are available) is 69.90. The average annual relative humidity in the past 30 years is 69.17.³¹

SOIL TEMPERATURE

None of the previous North Carolina climate studies looked at soil temperatures. However, a presenter at a gardening lecture conjectured that due to presumed warming temperatures a type of plant-parasitic worm (nematode) was migrating into warming soils in Wake County.

According to NOAA, there are two sources of soil temperature records in North Carolina, (1) the USDA Natural Resources Conservation Service, National Water and Climate Center and (2) the State Climate Office of North Carolina. However, the USDA source only has one station gathering soil temperature information and it is located in a far eastern part of the state in Plymouth, Washington County, and has only been reporting soil temperatures since 1994.

The State Climate Office of North Carolina, however, operates two weather stations in Wake County reporting on soil temperatures, the Lake Wheeler Road Field Lab and the Reedy Creek Field Lab. According to the SCONC these “ECONet” type stations are the only source of monitored and reported soil temperature recording data in the state.³² The Lake Wheeler station has been reporting soil temperatures since 1982 while the Reedy Creek Lab has been reporting them since 2001.

However, each station has had missing time periods and other irregularities in reports of its figures. First, there is some odd reporting of records for the Lake Wheeler station. Its soil temperature records from 1982–2022, when accessed on March 3, 2023, contained missing values for 12 years, or 1993–2003 and 2008. However, when these same records for 1982–2023 were accessed on February 4, 2024, the report listed only five years of missing values, or 1993–1997, with no explanation of how previously missing temperature values from over 20 years ago were now included. See, these two reports at endnote 33.

Further, when the Reedy Creek records were accessed on March 23, 2023, the report reflected that this station was missing (including obviously incorrect recordings such as -499.3°) seven different years of soil temperature recordings since it began taking readings in 2001. However, when accessed on February 4, 2024, without any explanation, each of the years had a figure in it. However, these figures remain suspect as while they all are around the approximate 60° mark and the reading for the year 2012 is only 35.7°. ³³ These significant missing periods of time and mysteriously changing reports (see endnote 33) prevent a clear and credible analysis of soil temperatures over a relevant and useful period of time.

However, since soil temperatures are so important to gardening, let’s at least take an informal, even if not scientifically reliable, look at the average annual soil temperatures at the Lake Wheeler station based on the most recent information available. Since the Reedy Creek station last year had only has 10 complete years of information since its installation in 2001 and this year still has suspect figures, a review of its readings is not warranted.

To the extent the Lake Wheeler Road station’s most recent average annual soil temperature records are from 1982 through 2023, but still missing five years from 1993–1997, the first 30 years averaged soil temperatures (again, not counting 1993–1997) of 63.10°. The most recent 30 years (also not counting 1993–1997) reflects average annual soil temperatures of 62.79°.³³

To the extent there is available soil temperature data, the Lake Wheeler station reflects somewhat cooler average annual soil temperatures in the past 30 years compared with its first 30 years starting in 1982, so no warming trend. In any event, due to the recent beginning dates of observations and the large amounts of missing and changing data, these stations cannot confidently be used to determine trends in soil temperatures in Wake County. Consequently, there is no long-term, reliable evidence to support an assertion that soil temperatures have experienced any significant, enduring warming in the Central Piedmont area of North Carolina, and the lack of recording history into the mid-20th century and beyond preclude any analysis of precedential temperature records.

DROUGHT

The 2015 Climate Change in North Carolina report did not find any long-term trends in either the Piedmont or the entire state with respect to droughts.² The 2020 NC Climate Change study concluded that droughts are a natural part of North Carolina’s climate and did not find any increase in droughts over history.³

Additionally, in the most recent North Carolina Department of Environmental Quality, Division of Water Resources, NC Drought Management Advisory Council Annual Report (2023), it was stated that no clear historical trend had been seen and summarized North Carolina’s history of droughts as follows:

“North Carolina experienced extreme drought conditions from 1925 through 1927 with PHDI values reaching -4.1 at one point. A very wet period followed and then an extreme 16 drought occurred in 1932–1933. This extreme drought period saw the lowest individual monthly PHDI value of -4.74. Occasional, Moderate Droughts occur in the 1940’s and 1950’s but it wasn’t until the late 1980’s that extreme drought returned. The PHDI reached a low of -4.6 in July 1986. Moderate to wet conditions returned in the 1990’s but two of the most extreme droughts in North Carolina’s recorded meteorological history occurred between 2000 and 2010. One of the wettest years also occurred during this period. Since 2010, conditions have been less extreme but highly variable swinging from moderately wet to moderately dry. … The North Carolina PHDI values for the report period averaged -1.76 (NOAA, 2023). These values reflect the very wet winter period and a moderately dry spring. Since the 2007 to 2008 drought, conditions had been trending wetter than normal. However, conditions over the last year swung back to below normal … .”³⁴

These conclusions came along with the following chart showing the occurrences and severity of droughts in the state since 1895 to 2021.

As for Wake County, NOAA’s National Integrated Drought Information System contains information in graphic format about the frequency and severity of droughts in specific counties.³⁵ Here is a chart of the drought history in Wake County from 1895 through 2023:

As can be seen, the dark, tall thicker red spikes reflect extreme drought conditions over time, with the last one in 2007 and not much since then and with apparent frequent and intense drought activity in the 1920s and 1930s.

The last drought of significance in memory that brought about water use restrictions to Wake County residents was in 2007. Even so, the State Climate Office of North Carolina in its 2015 report concluded that longer-term data “suggests drought periods in the past that may have been more severe than those witnessed in NC in modern times.”²

In short, from the beginning of drought-related measurements in the late 1800’s, North Carolina occasionally experiences extreme drought and annually experiences some periods of drought in different parts of the state and this pattern continues to the present.

Lastly, a word about a term that is appearing in more informal reports on this topic, that is, the phrase, “flash drought.” The above noted report by the NC Drought Management Advisory Council Annual, to its credit, focused on the serious subject matter of actual droughts and did not engage in the use of the non-serious term “flash drought.” Unfortunately, the State Climate Office of North Carolina has begun to use the term to describe what has historically been known as a “dry spell.”

The 2002, 2015 and 2020 North Carolina studies did not even consider the subject of a dry spell worthy of investigation or discussion and the term “flash drought” was never used. Lastly, if “flash droughts” were such a scientifically established phenomena, there would be an accepted definition of what they are. However, a group of scientists, including two from NOAA, tried to determine what a “flash drought” was and found that there are at least 29 different definitions in the scientific literature.³⁶ Accordingly, it is not a credible, established meteorological principle, and instead apparently a recent catchy phrase used by those who want to impart a sense of alarm, instead of focusing on the serious issue of real drought.

HURRICANES

Have extreme weather events such as hurricanes become more frequent and/or more powerful? Hurricanes in the past have significantly affected Wake County and the Piedmont and can cause a great deal of destruction, including, from a gardener’s perspective, the toppling of trees and washing out and blowing away of gardens.

Initially, though, from an on-the ground perspective, a recently retired manager of the City of Raleigh Urban Forestry Department commented that the only widespread destruction of trees in the area in recent memory has been from hurricanes Hazel in 1954 and Fran in 1996.³⁷

As far as the frequency of hurricanes affecting the state as a whole, a chart from the State Climate Office of North Carolina illustrates that the frequency of all storms affecting the state of North Carolina has declined in the last decade and had its peaks in the 1950s and 1970s.³⁸

The graph above shows the total number of all types of storms (however weak) affecting North Carolina by decade.

If the storms less powerful than tropical storms are removed from consideration, this is what the chart looks like for tropical storms and all hurricanes³⁸

The above charts clearly illustrate that the number of tropical storms and hurricanes affecting North Carolina has precipitously fallen off over the decades.

The State Climate Office of North Carolina removed these charts illustrating the decline in the number and intensity of hurricanes affecting North Carolina from its website since the publication of this author’s original article in 2021. However, SCONC reports no hurricanes affecting North Carolina in 2022 or 2023 so the information communicated by these charts remain the same.

Until 2022 the SCONC provided data as to the historical statewide number of storms greater than or equal to 25 miles per hour making direct landfall on North Carolina. This historical data, when compiled in a bar chart, reflects this information showing the number of such storms decreasing in the past several decades:

Storms of the same wind velocity “affecting North Carolina” according to the SCONC look like this, with a marked decrease in the past decade:

Examining the data from more of the center of the state, the following charts from the SCONC show the frequency and intensity of all storms categorized as “tropical storms” (40 miles per hour or more) since 1851 and within 100 miles of the original State Capital at 1 E. Edenton Street in Raleigh. This data contains reports of all storms with winds of 40 mph or more, so includes all tropical storms and hurricanes within 100 miles of the Wake County area through 2023.³⁸

The above charts reflect that since 1851 the frequency of tropical storms and hurricanes within 100 miles of the Original State Capital in Raleigh has been as follows:

1994–2023: 3 hurricanes, 10 tropical storms

1964–1993: 5 tropical storms

1934–1963: 8 tropical storms

1904–1933: 7 tropical storms

1874–1903: 3 hurricanes, 15 tropical storms

1851–1873: 1 hurricane, 7 tropical storms (only 23 years)

Notable is the year 1893 which had three tropical storms, including a Category 1 hurricane. There have been only four tropical storms and no hurricanes in the past 10 years.

The below chart illustrates the above information.

But some commentators have said that even if the hurricanes are less frequent, they have become more powerful. So, let’s look at the same history of tropical storms above, but set out and ranked by strength in terms of mile per hour winds (measured down to a maximum of 40 mph).

Placed in chart form, below is the above information through 2023 which reflects that storm intensity has been decreasing over the decades.

As shown above, for the past 173 years tropical storms and hurricanes in the Wake County area, and the state itself, have not been becoming more frequent nor more powerful in recent years. They were more frequent and stronger farther back in history.

SPRING AND FALL FREEZE DATES

All gardeners pay attention to freeze dates, especially the Spring freeze date (which in meteorological circles is referred to as the “last” freeze date and the Fall freeze date is the “first” freeze date). Gardeners’ Spring planting decisions revolve around the average last freeze date and impatient gardeners spend a great deal of money on early Spring plant purchases and make strategic decisions about moving plants from the inside, whether it be the house, garage or greenhouse, to the outdoors.

According to NOAA, the average Spring freeze date in Wake County and surrounding area, per the RDU station (1887–2023), is April 4th. The average Fall freeze date is November 4th.³⁹

The earliest last Spring freeze date is March 1st in 1935 and the latest last Spring freeze date is May 9 in 1956.

Here are charts depicting these dates over time, first for Spring through 2023 and then for Fall through 2023. To the extent that global warming advocates warn that the last Spring freeze date is, or will be, occurring earlier and earlier in an unprecedented manner as the growing season allegedly becomes longer, this is not borne out by the historical data which shows most of the earlier Spring freeze dates occurring in the first half of the last century.

Similarly, the “first” Fall freeze date has not been delayed in a significant, enduring and unprecedented manner as borne out by the following chart.

Gardeners should be in verify mode when presented with “average freeze date” calculations, primarily to ensure the information is the best available and applicable to their location. An example is a Wake County COOP type weather station which has been used to represent average freeze dates, the Falls Lake station, COOP id #312993, images and a description of which appear above in this article. While this station was first put into service in 2000, it is missing significant periods of data and has been situated in three different locations. The station did not start reporting data in years in which both the Spring and Fall freeze dates could be determined until 2009 and overall is missing over 35% of the first/last freeze dates for the period from 2000–2023. It also failed to report any first freeze date for the Fall of 2019.

By contrast, the RDU station information has yielded data for each year since 1887, as seen below:

For those gardeners interested in determining freeze dates in your vicinity, you can consult the weather station at the nearest Primary Local Climatological Data Stations (see endnote 11) or at your nearest and largest airport since these are likely to have more complete data than other stations. In any event, freeze date and growing season information is easily obtained for any station by going to the climate center designated by NOAA as the lead agency for determining freeze dates at locations across the country, the Midwestern Regional Climate Center (“MRCC”): https://mrcc.purdue.edu/CLIMATE/index.jsp and see further details and instructions at endnote 39.

PLANT HARDINESS ZONES

The developers of the plant hardiness zone maps have stated that these zones, or any change in the zones, should not be used as a proxy for whether climate change is occurring, primarily because they are based only on one low temperature reading a year. Even so, it is interesting to note that Wake County, and many other areas in the Piedmont area of North Carolina recently were reassigned to plant hardiness zone 8(a), which actually is where they were for many years from 1928–1990. See related article here.

GROWING SEASON

The length of time between the two average Spring and Fall freeze dates is referred to as the growing season and its current average length in the Wake County and surrounding Piedmont area is 213 days³⁹.

Here is a decade-by-decade numerical summary of the length of the growing season since 1887:

1888–1893: 218

1894–1903: 227.3

1904:1913: 219.4

1914–1923: 224.1

1924–1933: 235.6

1934–1943: 236.3

1944–1953: 206.4

1954–1963: 201.7

1964–1973: 195.7

1974–1983: 193.3

1984–1993: 204.1

1994–2003: 207.5

2004–2013: 214

2014–2023: 216.2

The average length of the growing season in the past 30 years (212.7 days) is shorter than the historical average of 213 days and markedly shorter than the time period in the late 1800’s and the first half of the last century (for example the 30-year time period from 1912–1941 the average length of the growing season was 232.20 days).³⁹ So, the recent growing season is significantly shorter than the average during periods in the first half of the last century.

Here are these figures in chart form through 2023.³⁹:

The chart illustrates that our recent growing season lengths are not unprecedented and are shorter than the majority of historical recorded periods.

CONCLUSIONS

The 2002 and 2015 reports on climate change in North Carolina conclude there are no significant, enduring and unprecedented statewide climatological trends that are associated with global warming. A third study in 2020 reported temperature trends in the Piedmont region reflective of global warming present in only some, but not most, temperature categories, with no increase in extreme weather events, and overall found only a less than 1 degree rise in average temperatures since 1895. A 2022 study found that there have been no unprecedented change in 84% of three average temperature categories from North Carolina’s six Primary Local Climatological Data Stations.

This article’s examination of average temperatures in the Wake County area in North Carolina’s Piedmont region found recent 30-year average temperatures rising, but in similar fashion of past periods, average minimum temperatures decreasing, and average maximum temperatures increasing, although periods of increase also occurring in the last century. While days with minimum temperatures of 75 degrees or more occurred more frequently than average in periods in both the 1900’s and this century, the only study to address the issue (the 2015 State Climate Office Climate Change Report) found that this only occurred in urban, nor rural, areas and was not related to global warming.

Looking at special categories of interest to gardeners (humidity, soil temperature, average freeze dates, growing season) reveals that there do not appear to be any abnormal and unprecedented trends occurring and if anything, seasonal coolness trends are indicated with shortening growing seasons in recent years compared to the last century. Extreme weather events such as 3” rains and hurricanes have not increased in frequency or intensity, with hurricane activity and intensity clearly decreasing locally and across the state over the past several decades. Drought has not been an issue for a long time and in any event is noted to appear periodically throughout history.

By Tom Packer, North Carolina State Extension Certified Master Gardener Volunteer of Wake County (Chair - Management Team and Gardening Helpline), Past-President of the Gardeners of Wake County, Board Member of the North Carolina Cooperative Extension Agricultural Programs Foundation and longtime backyard farmer in North Carolina and Northern California. All this article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated, including those identified above. This article originally was published on February 19, 2024.

ENDNOTES

[1] https://drive.google.com/file/d/1MI4vnDo9vrH-YRSbwpIQqjhYnB5PnHeS/view?usp=sharing

[2] https://web.archive.org/web/20150420025024/http://www.nc-climate.ncsu.edu/climate/climate_change and https://drive.google.com/file/d/1Y4YgPJ7L0-YW7b3k1vGGTggEXw8AOCFs/view?usp=sharing

Note: This report was found in a website archive search site. It was captured by the website archive service on April 20, 2015 and prior dates. This report no longer appears on the website of the State Climate Office of North Carolina.

[3] https://ncics.org/wp-content/uploads/2020/10/NC_Climate_Science_Report_FullReport_Final_revised_September2020.pdf

Heating Degree and Cooling Degree Days, which are used to quantify the energy needed to heat or cool buildings and houses, were found to vary over time in concert with the area’s annual average temperature and are not addressed in this article.

[4] https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00861;view=iso; https://www.ncei.noaa.gov/metadata/geoportal/rest/metadata/item/gov.noaa.ncdc:C00861/html

See, “Publications citing this dataset should also cite the following article: Matthew J. Menne, Imke Durre, Russell S. Vose, Byron E. Gleason, and Tamara G. Houston, 2012: An Overview of the Global Historical Climatology Network-Daily Database. J. Atmos. Oceanic Technol., 29, 897–910. doi:10.1175/JTECH-D-11–00103.1.”

[5] https://medium.com/@tpacker25/north-carolinas-climate-and-it-s-six-primary-weather-stations-c1bccd68d905

[6] Personal communication with author — July 20, 2020.

[7] While the RDU weather station is a First Order station, identification #13722, according to a NOAA representative all major airport weather stations are also assigned a COOP station number, here, RALEIGH AP #317069, even if they are not COOP-type stations. So, there is only one weather station at RDU, it is a First Order station, and there is not a separate COOP station at the site.

[8] See,

https://threadex.rcc-acis.org/

re NOAA’s ThreadEx records (click on “About.”).

[9] APPENDIX B — Accessing NOAA Daily Temperature and Precipitation Extremes Based on Combined/Threaded Station Records, NATIONAL WEATHER SERVICE INSTRUCTION 10–1004, MAY 17, 2020, “This new ThreadEx data set provides a consistent basis for the reporting of daily extremes for the longest period of time meaningful. With the ThreadEx effort, maximized, consistent, updated daily extremes will be available for government, partner, and general public (especially media) use.” And see, Yuchuan Lai, David A. Dzombak, Use of Historical Data to Assess Regional Climate Change, Journal of Climate, 10.1175/JCLI-D-18–0630.1, 32, 14, (4299–4320), (2019), citing Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003: Temporal variations of extreme precipitation events in the United States: 1895–2000. Geophys. Res. Lett., 30, 1900, “The availability of these pre‐1948 daily data affords an opportunity to perform studies with unprecedented detail, extending back to the late 1800s of trends in short duration extreme events.”

[10] Use of Historical Data to Assess Regional Climate Change, Yuchuan Lai and David A. Dzombak, Journal of Climate, American Meteorological Society, July 15, 2019, pages 4299–4320, https://doi.org/10.1175/JCLI-D-18-0630.1

[11] NATIONAL WEATHER SERVICE INSTRUCTION 10–1004, MAY 17, 2020, Operations and Services, Climate Services, NWSPD 10–10, Appendix C. The other five Primary Local Climatological Data Stations (PLCDs) in North Carolina are Asheville Regional Airport (AVL), Hatteras Billy Mitchell Airport (HSE), Charlotte Douglas International Airport (CLT), Greensboro Regional Airport (GSO) and Wilmington New Hanover Airport (ILM). These stations are regarded as “Primary” because of the extensive and manual quality control checks they are subject to, which other weather stations are not. (Per communication with NOAA representative on April 27, 2021).

[12]

http://xmacis.rcc-acis.org/

— Seasonal Time Series / Avg temp / Mean / por -2023 / Annual / Average of Months / Daily Station Selection 311535; https://docs.google.com/document/d/1YhsD2XL28UzRj1UXhSwc_DidEvOhuxqd/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[13]

http://xmacis.rcc-acis.org/

— Seasonal Time Series / Avg temp / Mean / por -2023 / Annual / Average of Months / Daily Station Selection 312993; https://docs.google.com/document/d/1kgw9fY-NoMUXtzqEW1GOIlnuIzyXjaJG/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[14] Communication from NOAA representative with author on January 21, 2021.

[15] The station identified as 317069 NSW COOP Raleigh AP is not included in this count of COOP stations as this is, per endnote 6, First Order station KRDU #13722.

[16] See: https://www.ncdc.noaa.gov/news/defining-climate-normals-new-ways

[17] See: https://drive.google.com/file/d/1MA7gw5GgsVCusiA8JwzZaUqvsFqRN6AV/view?usp=sharing and http://web.archive.org/web/20201114005450/https://planthardiness.ars.usda.gov/PHZMWeb/AboutWhatsNew.aspx

[18] Daly, C., M.P. Widrlechner, M.D. Halbleib, J.I. Smith, and W.P. Gibson. 2012. Development of a new USDA Plant Hardiness Zone Map for the United States. Journal of Applied Meteorology and Climatology, 51: 242–264 at 259.

[19] After entering the site at

http://xmacis.rcc-acis.org/

, for RDU historical records, enter Single Station, Seasonal Time Series, the weather record and time-period and select the station by entering its station, Raleigh area, and then RDU.

[20]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ av temp/mean/ por — 2023 / Station: Raleigh Area/ RDU

[21] Temporal Variations of Extreme Precipitation Events in the United States: 1895–2000, Kenneth E. Kunkel, David R. Easterling, Kelly Redmond, Kenneth Hubbard, American Geophysical Union (AGU), GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 17, 1900, September 09, 2003. https://doi.org/10.1029/2003GL018052

[22]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ min temp/mean/ por — 2023 / Station: Raleigh Area/ RDU

[23]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ max temp/mean/ por — 2023 / Station: Raleigh Area/ RDU

[24]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/min temp/number of days/Threshold: ≥ 75°/ por — 2023 / Station: Raleigh Area/ RDU

[25]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ precipitation/sum/ por — 2023 / Station: Raleigh Area/ RDU

[26]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ precipitation/number of day/ equal to or greater than 1 inch/ por — 2023 / Station: Raleigh Area/ RDU

[27]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ precipitation/number of day/ equal to or greater than 2 inches/ por — 2023 / Station: Raleigh Area/ RDU

[28]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ precipitation/number of day/ equal to or greater than 3 inches/ por — 2023 / Station: Raleigh Area/ RDU

[29]

http://xmacis.rcc-acis.org/

: single station/seasonal time series/ snowfall/sum/ por — 2023 / Station: Raleigh Area/ RDU. Reported trace amounts were counted as .01 inches.

[30] http://xmacis.rcc-acis.org/: single station/seasonal time series/ snowfall/number of day/ ≥.1 inch/ por — 2023 / Station: Raleigh Area/ RDU

[31] This information formerly in 2021 was accessible at: https://climate.ncsu.edu/cronos/?station=KRDU&temporal=monthly%20Average%20Daily%20Relative%20Humidity/average/percent%20(%)/height%20%E2%80%93%202m . However, now it must be accessed after registration with the State Climate Office of North Carolina at: https://products.climate.ncsu.edu/cardinal/ The humidity readings obtained can be found at: https://docs.google.com/document/d/1pnNDqG8UINEi6lTTozeNC2bRkwSm3NbU/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[32] Communication with author on July 27, 2020.

[33] This information formerly was available at:https://climate.ncsu.edu/cronos/?station=LAKE&temporal=monthly%20Soil%20temperature%20daily%20mean/average/0.1m

https://climate.ncsu.edu/cronos/?station=REED&temporal=monthly%20Soil%20temperature%20daily%20mean/average/0.1m

The information is now accessible at https://products.climate.ncsu.edu/cardinal/request/ (account registration and sign-in required). See these stored documents at the following links for the mentioned reports from the Lake Wheeler and Reedy Creek weather stations accessed in 2023 and 2024:

(1) https://docs.google.com/document/d/1hUr7Da9UTD_e2Di-_WU6hsXIzka9Y9zE/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

(2) https://docs.google.com/document/d/1EcgJQmTDSpyJkGixH-Z_sXd2U4Rgiw7g/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

(3) https://docs.google.com/document/d/115Y1YToIHGlDAOG2eoBlnBxUGeIHEDEK/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

(4) https://docs.google.com/document/d/1gdlEVOIN8NaYhowmhUG6_zLTEtiQjAIf/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[34] https://www.deq.nc.gov/legislative-reports/north-carolina-drought-management-advisory-council-report/open [ Predictions and a non-sensical statement at end of paragraph omitted, see above for full text of quote].

[35] https://www.drought.gov/historical-information?state=north-carolina&countyFips=37183, 1895-Present Monthly

[36] https://stateclimate.org/pdfs/journal-articles/2021_1-Lisonbee.pdf

[37] September 11, 2020 post on Nextdoor.com.

[38] https://climate.ncsu.edu/climate/hurricanes/statistics. While this particular bar chart has been removed by the State Climate Office of North Carolina from its website, its current search function for the same type of storms does not reveal any such storms after 2019: https://products.climate.ncsu.edu/weather/hurricanes/affecting/?state=NC&buffer=150. All data accessed for this section in February, 2024.

[39] https://mrcc.purdue.edu/CLIMATE/index.jsp

Daily observed data, Seasonal, Seasonal Statistics

Growing season/ ≤ 32°/1887–2023, Find a station, NC, ThreadEx/Raleigh Area (Station ID: RDUthr). Sign up for free account and sign in. Once logged in, change the daily station to KRDU at the top of the screen. Historical first and last freeze dates are located in the menu on the left under Daily-Observed Data — Seasonal- Seasonal Statistics. Select the Frost Season and if necessary, change the temperature threshold to ≤ 32°. Figures for years 1893, 1894, 1925 and 1926 included from report accessed on 3/21/2023. A 2/9/2024 email sent to mrcc@purdue.edu inquiring about the missing data for these four years in the report accessed on 2/8/2024 did not receive a response. NOAA has designated the Midwestern Regional Climate Center (MRCC) as the lead climate center for determining average freeze dates around the country.

[40] Definition per the MRCC.

The National Weather Service has designated six weather stations as Primary Local Climatological Data sites (PLCD) in North Carolina.¹ They are located in Asheville, Charlotte, Greensboro, Raleigh, Wilmington and Hatteras, representing the breadth of the state from east to west. Their locations are depicted on the above map.

These “primary” stations are what the National Weather Service also refers to as “First Order” stations and are the highest quality weather stations in the United States, being subject to the most stringent quality control measures. There generally are three kinds of weather stations in descending order of quality and reliability, First Order (also known as Primary), Secondary and then COOP. First Order stations are monitored by professionals and reliably record hourly (and even sub-hourly) observations and are subject to additional and more rigorous quality checks, including manual quality checks, than all other stations. There are only 274 First Order Stations in the country and they have more instrumentation and include more data than all other types of weather stations.²

This article examines the historical climatological data from these six Primary weather stations by looking at their average temperature, average maximum temperature and average minimum temperatures over the 100+ years of records. First the historical temperatures for the three categories are determined by adding up all the annual temperatures and dividing by the number of years of records available. Then the average temperatures for the past 30 years (through 2021) are calculated. Next, it is determined whether that reading is higher than the average; if so, then whether or not another 30-year period starting before 1950 also had a higher than average temperature in that category is determined.

The results are set out below but in summary, this review found that in only three out of 18 instances were there rises in average temperatures that also did not have a corresponding rise in the average temperature being measured in a 30-year period starting prior to 1950.

Here is an image of the installation that includes the Primary/First Order weather station in Raleigh, North Carolina (id #13722) located at the Raleigh-Durham Airport (RDU)³.

Here is a close-up look at another Primary weather station⁴:

The RDU Primary station has been in place since 1944 and is professionally managed and monitored, while recording hourly and sub-hourly observations. It has a 100% record of days recording and reporting the weather data discussed in this article and presently records 95 weather parameters. Through the National Oceanic and Atmospheric Association (NOAA) ThreadEx program⁵, historical weather observations from as far back as 1887 by its predecessor station are included in the weather records provided.⁶ Use of weather stations in the NOAA ThreadEx program is an accepted, recognized method of assessing regional climate trends in the United States.⁷

This article examines historical climate data from the six Primary/First Order weather stations in North Carolina and assesses whether significant, enduring and unprecedented temperature trends are occurring, or not. This article also will discuss why the weather records from these six stations represent a viable and accurate reflection of historical climate trends in these regions of the state rather than the methods employed in prior climate change studies of using many, unidentified lesser quality and less reliable weather stations.

North Carolina is known to be divided into three regions, the Mountains in the West, the Piedmont region in the middle and then the Coastal area to the East.

A Primary/First Order station is located in each of these three regions. However, prior climate change studies in North Carolina have not focused on utilizing these six weather stations in order to examine regional climatic trends. An examination of past climate change studies reveals that they conclude that sweeping conclusions on climate trends for the entire state are not possible due to the geographic and climatic variety present throughout the state and that such assessments should be done on a more local, regional basis.

HISTORY OF CLIMATE CHANGE STUDIES IN NORTH CAROLINA

There have been three major climate change studies in the past couple of decades.

2002 Climate Analysis

Two leaders of the State Climate Office of North Carolina (SCONC), published a 2002 paper in Environment International titled Analysis of Climate Trends in North Carolina (1949–1998).⁸ This study found that North Carolina has one of the most complex climates in the country and that most of the climate trends found were local, not statewide. The authors of the study stated, “Local scale climate analysis can more accurately represent the complex climate that exists in North Carolina …”

The study found on a statewide basis that while temperatures in the last 10 years of the study were warmer than usual, they were not warmer than the temperatures experienced in the 1950’s. Maximum temperatures had remained fairly constant and there was no widespread pattern showing increasing minimum temperatures across the state.

2015 Climate Change in North Carolina Report

This report, by the State Climate Office of North Carolina, looked at a much longer time period, investigating weather records back to the late1800’s.⁹ The report found no warming trend in the 113-year study period starting from 1895. While there was some warming since the mid-1970’s, it was found to be not unprecedented and similar to the warming observed from 1910–1950. The 2015 SCONC report stated that in North Carolina there is “no meaningful trend that is associated with global warming.”

While the report noted a rise in minimum temperatures, this was only in urban areas and was not found in rural areas. The report concluded that this possibly was due to urban development, but it was not due to global warming. The SCONC summed up its view on climate change in 2015 by pointing out that it also had analyzed dozens of other temperature data “(including seasonal patterns, days with extreme high and low temperatures, a variety of temperature thresholds, degree days, growing season data, frost data), and one common thread joined them all: “… the trends are generally flat …” The State Climate Office concluded that, “… local climate variability is so high in North Carolina that significant trends are difficult to deduce.”

2020 Climate Study — North Carolina

This study was done in response to an order of the Governor of North Carolina after his 2016 election.¹⁰ The above two prior climate change studies were not mentioned in the study, nor is there any mention of the history of climate changes studies in the state. It addressed climate issues statewide, and also in the three main regions of the state, Western Mountains, the Piedmont and the Coastal Plain. The 2020 study set forth conclusions as to climate trends for the entire state, but ambiguously concluded, as to average annual temperatures, that recent temperatures had increased statewide “about” 1° since 1895 (but nowhere in the report is the actual figure reported nor use of the word “about” defined). Further, it is not made clear whether this “about 1°” figure was compared to the existing average annual temperature in 1895 or compared to the average annual temperature for all the years since 1895.

The study also avoided the important question of whether, for example, there also was a similar “about” 1° rise in average annual temperature for the 30-year period from 1921–1950, or some other earlier period. The study did not engage in comparing recent periods of time with earlier ones and with at least 30 years of climate records.

This is quite important for two reasons.

First, NOAA has issued guidance that when trying to determine what the climate is like during a period of time (what NOAA refers to as a “climate normal”) at least 30 years of weather observations should be used.¹¹ The USDA has even stated that at least 50–100 years of data of overall average temperatures are needed to assess changes in the climate.¹² NOAA’s use of at least 30 years of data is longstanding and based on the instructions of almost a century ago by the International Meteorological Organization to calculate climate normals by using 30-year periods. NOAA also relies on the general rule in statistics that at least 30 numbers are needed to obtain a reliable estimate of their mean or average.¹¹

Second, comparison of a recent 30-year “climate normal” to a past 30-year climate normal yields information as to whether a recent climate trend not only is significant and enduring, but whether it is unprecedented. While the 2020 study acknowledged that the first half of the 20th century contained decades with “some of the warmest periods in North Carolina’s history,” in computing the state’s average temperature, the 2020 study only compared the single 10-year time-period of 2009–2018 with another single decade, 1930–39. The report found a difference of “about 0.6°” but then moved on without further discussion or “30-year climate normal” to “30-year climate normal” comparisons with other prior temperature phases in the 1800’s or 1900’s. However, as discussed above, NOAA standard practice dictates that when comparing climate normals from periods of time to use 30-year, not 10-year, periods.¹¹ Further, climate records through the 1950’s are deemed significant by the climatic research community as they occurred during a pre-industrial period reflective of natural (that is, non-manmade) climate conditions. As the lead author of the 2020 North Carolina Climate Study wrote, “Because industrial development was minimal until about midway through the 20th Century, the earlier record reflects mainly natural variability.”¹³

For a more detailed discussion of these climate studies as well as a discussion of them and actual historical climate records in the context of climate conditions of most interest to gardeners, see A GARDENER’S LOOK AT THE CLIMATE IN NORTH CAROLINA BACKYARDS: HISTORY OF CLIMATE STUDIES AND PIEDMONT REGION CLIMATE — 2023 UPDATE.¹⁴ [While this article was originally published on September 26, 2022, it's republication here contains reference to this more recent 2024 article which updates findings through 2023.]

The 2020 study’s conclusions of state-wide climatic trends to date, however ambiguous and inconsistent in the time periods used, are undercut by two basic concepts.

One, the study should have heeded the teachings and admonitions of the prior climate studies identified above that “… local climate variability is so high in North Carolina that significant trends are difficult to deduce.”⁹ The 2020 study did not, like the prior studies before it, acknowledge the difficulty in arriving at sweeping assertions of “climate change” across the state. The problem with this approach was articulated by the authors of the 2002 study who wrote that, “North Carolina has one of the most complex climates in the U.S. Factors such as complex topography in the west and warm waters off the east coast combine with weather patterns to produce a region with locally variable weather and climate. Local scale climate analysis can more accurately represent the complex climate that exists in North Carolina, and offers new insights into precipitation and temperature patterns.”⁸

Consequently, this article focuses on climatic records and trends contained in the records of observations at the six Primary, or First Order, weather stations described above and which are geographically disbursed across the state such that all three regions, the Mountains, the Piedmont and the Coastal Area are represented. These stations, in addition to being at the top of the pecking order among weather stations in terms of quality, also have the advantage of containing weather data from as far back as the late 1800's.

Two, the weather stations mostly used in the 2020 climate change study are not as reliable and accurate as the First Order stations. They also have been in use mostly only in recent years and so cannot offer the data necessary to compare to prior NOAA climate normals/periods of time from the late 1800’s and the first half of the 20th century.

The 2020 study does not identify the individual weather stations it used (all weather stations have unique identifying numbers assigned by the National Weather Service). However, the 2020 study acknowledges that it included and primarily relied on the use of so-called “COOP” stations which, as mentioned above, are the least reliable type of weather station.

COOP stations (part of a Cooperative Observer Program), while more numerous, are monitored by volunteers (such as a homeowner with a station placed on his/her property) which can result in temporal gaps in weather data records and other quality control issues. While volunteer COOP observers can play a role in providing weather information for forecasting and basic weather information, periods of missing weather recordings can preclude reliance on them in determining long term trends. None of the three North Carolina climate change studies discloses whether any minimum station quality qualifications and criteria were employed or whether any COOP stations were disqualified from use.

Here is an image of a COOP weather station, (id #311535), located in Cary, North Carolina:

It is located in the front yard of a home in a residential neighborhood in Cary and with temperature observations beginning in just 2001. It monitors three weatherconditions, temperature, precipitation and snowfall. It is reported as missing 251days of temperature observations.¹⁵

This is the Falls Lake Weather COOP station (id #312993). It is in the backyard of a home in a residential neighborhood.

A closer look reveals that it is a weather apparatus manufactured by the Davis instruments company which can be purchased online.

This station has been in use just since 2000 and is reported to have 505 missing days of temperature data in its average temperature reports.¹⁶

Let’s look at one more COOP station in the state, this one near the coast in southeastern North Carolina, Shallotte, Brunswick County, station id# 317813. Once you make your way past the old cars and the shed, in a small clearing the COOP station can be found.

This station has been in service only since the year 2000 and is missing 267 average temperature readings, with 13 missing days of readings as recently as the past five years.¹⁷

Let’s now take a look at all the COOP weather stations in one county. Here is the list of COOP stations in Wake County, North Carolina as provided by NOAA.¹⁸

Of the 14 COOP type weather stations in Wake County¹⁹, six have not been functional this century and three stopped functioning in 2010, 2012 and 2022. Of the remaining five stations, three stations have start dates since 2000 and one since 1993. So, for example, three stations with only 20 years of weather data, and missing hundreds of days of data, presumably were included in the calculations by prior climate change studies to determine whether there have been climate changes since 1895. As explained above, NOAA’s guidance is that when trying to determine what the climate is like during a period of time (what NOAA refers to as a “climate normal”) at least 30 years of weather observations should be used.¹¹ Lastly, unlike, for example, the RDU First Order station in Wake County, none of these Wake County COOP stations have an uninterrupted report of complete climate records from 1887.

As noted above, the 2020 study did not identify which weather stations it used. However, it explained that it obtained its climatic data from “NOAA’s National Centers for Environmental Information (NCEI) Climate Divisional Dataset (nClimDiv), version 2.” However, it should be noted that this dataset was created due to the recognition that historical climatic records based on the COOP system of weather stations contained many significant errors. NCEI itself acknowledged that various factors reflecting the unreliability of the COOP type station such as changes in location and measurement technology resulted in, “…large errors in calculating long-term climate trends.”²⁰ As a result, NCEI developed a “temperature data homogenization algorithm” in an attempt to reduce, but not eliminate, the errors in climate trend calculations. However, whatever type of algorithm was devised by modern day climate scientists, it still cannot account for the paucity of COOP stations that have been operating in North Carolina for long, historical periods of time. As we saw above, just in Wake County alone, there are no COOP stations operating continuously since 1895, with several only functioning for short periods of time and some only since the year 2000. Also, an algorithm cannot make up for missing data, with many if not most COOP stations having significant missing temperature records.

In a confounding twist, the 2020 study acknowledged that it used a different data set for all of its graphics depicting temperatures and precipitation. Instead of using the dataset identified just above (nClimDiv) from which it obtained its climate information, it instead turned to, “NOAA NCEI’s Global Historical Climatology Network-Daily (GHCN-D), version 3.” The study did not reconcile how it used climate information from one dataset for its conclusions, but then used data from a different data set to illustrate these conclusions in its graphs and charts. As to use of the GHCN-D network, however, NOAA acknowledges that two-thirds of the stations in this network only record precipitation. NOAA further states that anyone using this dataset should also cite a published article which found, according to NOAA, that, “In general, the stations providing daily observations were not managed to meet the desired standards for climate monitoring. Rather, the stations were deployed to meet the demands of agriculture, hydrology, weather forecasting, aviation, etc.”²¹ The 2020 study did not cite this article.

EXAMINATION OF CLIMATE DATA FROM NORTH CAROLINA’S PRIMARY/FIRST ORDER WEATHER STATIONS

A review of the average temperatures, average maximum temperatures and average minimum temperatures for each of these six Primary weather stations was undertaken as far back in time as possible through 2021. The methodology is set out in detail at endnote 22.

This review resulted in 18 total average temperature categories, three for each station. The examination then looked at the results for the last 30 years (1992–2021) to see if the temperatures were higher, lower or the same than the overall average temperature category. If it was higher for the past 30 years, then the records were examined to see if another, prior 30-year period prior to 1950 existed which also reflected a rise in the average, maximum or minimum temperatures. If so, this would show that the rise in average temperatures in the last 30 years had occurred previously. To the extent “climate change” must be defined as a climatic trend that is significant, enduring and unprecedented, then a finding of prior rise in temperature during a previous 30-year period would mean that a recent rise in the past 30 years is not unprecedented.

This review found that in only three out of 18 instances were there rises in average temperatures that also did not have a corresponding rise in the average temperature being measured in a 30-year period starting prior to 1950. A list of the six Primary weather stations and of the 18 average temperature categories can be found at endnote 23. The only three findings of rising temperatures unaccompanied by prior corresponding rises in time were:

• Greensboro (station GSOthr) Average Minimum Temperatures for the last 30 years are higher than the average with no corresponding rise in a 30-year time period before 1950.

• Wilmington (ILMthr) Average Maximum Temperatures for the last 30 years are higher than the average with no corresponding rise in a 30-year time period before 1950.

• Hatteras (HSEthr) Average Maximum Temperatures for the last 30 years are higher than the average with no corresponding rise in a 30-year time period before 1950.

This leaves the 15 other climate categories at the six Primary weather stations which either were not higher than the historical average or, if they were, there was a 30-year period before 1950 which also had temperatures also were higher than the historical average.²³ Examples of these include:

• Charlotte (CLTthr) Average minimum temperatures for last 30 years is not higher than the historical average.

• Charlotte (CLTthr) Average temperature for last 30 years was higher than the historical average but the average temperature during 1921–1950 also was higher than the historical average.

CONCLUSION

The six highest quality, most reliable weather stations in North Carolina, which are located in locations from west to east and representative of the diverse and varied local climatic regions of the state, do not support the conclusion that when looking at average temperatures, as well as average maximum and minimum temperatures over a lengthy period of time, there is any significant, enduring and unprecedented change in climate in these locations. Only the three temperature rises in the weather stations noted above reflected a rise in average temperature not matched by a previous rise in temperature for a similar period prior to 1950, with the other 15 climate categories examine not demonstrating this.

By Tom Packer, North Carolina State Extension Certified Master Gardener Volunteer of Wake County (Chair - Managment Team and Gardening Helpline), Former President of the Gardeners of Wake County, Board Member of the North Carolina Cooperative Extension Agricultural Programs Foundation and longtime backyard farmer in North Carolina and Northern California. All this article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated.

ENDNOTES

[1] See, National Weather Service Instruction 10–1004, May 17, 2020,Operations and Services, Climate Services, NWSPD 10–10, Appendix C. https://www.nws.noaa.gov/directives/sym/pd01010004curr.pdf. The six Primary Local Climatological Data Stations (PLCDs) in North Carolina are Asheville Regional Airport (AVL), Hatteras Billy Mitchell Airport (HSE), Charlotte Douglas International Airport (CLT), Greensboro Regional Airport (GSO), Raleigh-Durham Airport (RDU) and Wilmington New Hanover Airport (ILM). These stations are regarded as “Primary” because of the extensive and manual quality control checks they are subject to, which other weather stations are not. (Per communication with NOAA representative on April 27, 2021).

[2] These high quality stations go through a 3rd, manual quality control procedure. Additional elements are computed and an Annual Edited LCD (an annual summary of weather data) is created. As an example, Wet Bulb (WB) is observed but Dew Point (DP) and Relative Humidity (RH) are computed. Daily average WB, DP and RH are computed from the hourly values that are observed or computed. Most of the secondary (Non-First Order) ASOS stations (~900) may have additional elements computed but do not have the 3rd manual QC of an Annual Edited LCD. [Personal communication from NOAA representatives with author — July 20, 2020 and April 27, 2001].

[3] While the RDU weather station is a First Order station, identification #13722, according to a NOAA representative all major airport weather stations are also assigned a COOP station number, here, RALEIGH AP #317069, even if they are not COOP-type stations. So, there is only one weather station at RDU, it is a First Order station, and there is not a separate COOP station at the site.

[4] See, https://www.wltx.com/article/weather/the-reason-why-we-get-our-weather-from-the-airport-weather/101-4f4c4133-2bf0-41ff-bb17-583d8e708319

[5] See, https://threadex.rcc-acis.org/ re NOAA’s ThreadEx records (click on “About.”) and see https://drive.google.com/file/d/1gMgMQ1X8R7PQa3AFXR-OmyhW3ye55y4V/view?usp=sharing

[6] APPENDIX B — Accessing NOAA Daily Temperature and Precipitation Extremes Based on Combined/Threaded Station Records, NATIONAL WEATHER SERVICE INSTRUCTION 10–1004, MAY 17, 2020, “This new ThreadEx data set provides a consistent basis for the reporting of daily extremes for the longest period of time meaningful. With the ThreadEx effort, maximized, consistent, updated daily extremes will be available for government, partner, and general public (especially media) use.”

[7] Use of Historical Data to Assess Regional Climate Change, Yuchuan Lai and David A. Dzombak, Journal of Climate, American Meteorological Society, July 15, 2019, pages 4299–4320, https://doi.org/10.1175/JCLI-D-18-0630.1

[8] https://drive.google.com/file/d/1MI4vnDo9vrH-YRSbwpIQqjhYnB5PnHeS/view?usp=sharing

[9] https://web.archive.org/web/20150420025024/http://www.nc-climate.ncsu.edu/climate/climate_change and https://drive.google.com/file/d/1Y4YgPJ7L0-YW7b3k1vGGTggEXw8AOCFs/view?usp=sharing

Note: This report was found in a website archive search site. It was captured by the website archive service on April 20, 2015 and prior dates. This report no longer appears on the State Climate Office of North Carolina’s website.

[10] https://ncics.org/wp-content/uploads/2020/10/NC_Climate_Science_Report_FullReport_Final_revised_September2020.pdf

[11] See: https://www.ncdc.noaa.gov/news/defining-climate-normals-new-ways

[12]See: https://drive.google.com/file/d/1MA7gw5GgsVCusiA8JwzZaUqvsFqRN6AV/view?usp=sharing and http://web.archive.org/web/20201114005450/https://planthardiness.ars.usda.gov/PHZMWeb/AboutWhatsNew.aspx

[13] Temporal Variations of Extreme Precipitation Events in the United States: 1895–2000, Kenneth E. Kunkel, David R. Easterling, Kelly Redmond, Kenneth Hubbard, American Geophysical Union (AGU), GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 17, 1900, September 09, 2003. https://doi.org/10.1029/2003GL018052

[14] https://medium.com/@tpacker25/a-gardeners-look-at-the-climate-in-north-carolina-backyards-history-of-climate-studies-and-00abd737399e

[15] http://xmacis.rcc-acis.org/ — Seasonal Time Series / Avg temp / Mean / por -2021 / Annual / Average of Months / Daily Station Selection 311535; https://docs.google.com/document/d/1aiKaB_l-NA3lzJvcemYK-UgcXN9xgwtG/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[16] http://xmacis.rcc-acis.org/ — Seasonal Time Series / Avg temp / Mean / por -2021 / Annual / Average of Months / Daily Station Selection 312993; https://docs.google.com/document/d/1X14m8krigTkwsTErnPQcDDMMc2nXMDaE/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[17] http://xmacis.rcc-acis.org/ — Seasonal Time Series / Avg temp / Mean / por -2021 / Annual / Average of Months / Daily Station Selection 317813; https://docs.google.com/document/d/1WF_-XW4ZEI2kzY22cad-oxk9D7C-ysz6/edit?usp=sharing&ouid=115138207048984797333&rtpof=true&sd=true

[18] Communication from NOAA representative with author on January 21, 2021.

[19] The station identified as 317069 NSW COOP Raleigh AP is not included in this count of COOP stations as this is, per endnote 3, First Order station KRDU #13722.

[20] https://www.ncei.noaa.gov/access/monitoring/dyk/nclimdiv-tmax-tmin

[21] https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00861;view=iso; https://www.ncei.noaa.gov/metadata/geoportal/rest/metadata/item/gov.noaa.ncdc:C00861/html

See, “Publications citing this dataset should also cite the following article: Matthew J. Menne, Imke Durre, Russell S. Vose, Byron E. Gleason, and Tamara G. Houston, 2012: An Overview of the Global Historical Climatology Network-Daily Database. J. Atmos. Oceanic Technol., 29, 897–910. doi:10.1175/JTECH-D-11–00103.1.”

[22] The data for the average temperature, average maximum temperature and average minimum temperature for all of the six Primary stations was obtained by using there three searches and inserting the name of the station:

• http://xmacis.rcc-acis.org/ : single station/seasonal time series/ avg/temp/mean/ por — 2021 / Station:_________

• http://xmacis.rcc-acis.org/ : single station/seasonal time series/ min temp/mean/ por — 2021 / Station: ________

• http://xmacis.rcc-acis.org/: single station/seasonal time series/ max temp/mean/ por — 2021 / Station: ________

The Applied Climate Information System (ACIS) was developed and is maintained by the NOAA Regional Climate Centers (RCCs). It was designed to manage the complex flow of information from climate data collectors to the end users of climate data information. See, https://www.rcc-acis.org/

[23] See, https://drive.google.com/file/d/1-RdfKjFn1rWrcUrekM6ztNauadPaZrnJ/view?usp=sharing

While browsing at the nursery, you pluck the pointed plastic label from the plant’s container, wipe off the moist soil with your finger and look at the plant’s name, sun requirements and its “USDA Zones.” Or, while shopping online, a major national nursery has “USDA Zone” next to each plant. When you click, the site explains, “There are very few rules in gardening, but perhaps the most important one is to work within your zone. Our zone finder tool is based on USDA Plant Hardiness Zone Map which is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location.”¹ Experienced gardeners know that by identifying the USDA plant hardiness zone in which they live it can then be determined if a particular plant can survive in the garden because it can withstand the average annual minimum temperatures associated with the zone.

There are of course other factors to be considered when determining the potential viability of a plant in a geographic location, but the use of the average annual minimum temperature provides a universal baseline to be used by all. As one of the early pioneers in the use of plant hardiness maps explained in 1940:

“Hardiness of plants is an indeterminable quantity, based not only on a plant’s resistance to minimum temperatures, but also on its resistance to maximum temperatures, and other factors such as lack of water, exposure, soil conditions, length of growing season, etc. It would be impossible to prepare a map depicting all these factors, though several might be included on a complex one. However, since a map based on the average annual minimum temperatures agrees in many instances with the known limit of hardiness of certain plants, these data were adopted as the basis for hardiness zones.”²

This view has endured and recently was expressed as:

“The extremes of winter cold are a major determinant of natural plant distribution and the successful cultivation and survival of long-lived plants. In the United States, the USDA Plant Hardiness Zone Map is the primary reference for defining and communicating the geospatial patterns of extreme winter cold to the horticulture and nursery industries, agrometeorologists, and plant scientists.”³

The history of how these zones came to be developed involves pioneering horticulturalists and colorful, hand-drawn maps from decades ago. This is the story of how the “USDA Zones __” on your plant tag came to be, what they mean and why they are still in use almost 100 years after the first plant hardiness maps were developed. There do exist what is becoming a myriad of various “plant hardiness” type maps which focus on other weather data, specific regions and different purposes, and which are beyond the scope of this article. Nonetheless, the USDA Plant Hardiness map remains the most commonly used standard by the plant industry and gardeners for assessing plant hardiness in the United States.⁴

This is the first known plant hardiness map, published in the Manual of Cultivated Trees and Shrubs Hardy in North America in 1927.

It was devised by Alfred Rehder

who for much of the first half of the 20th century years was an internationally renowned botanical taxonomist and dendrologist at Harvard University’s Arnold Arboretum in Boston.

Rehder divided the United States and southern Canada into eight zones consisting of 5° bands of differences in lowest mean temperatures of the coldest month of the year. As the initial attempt at establishing hardiness zones, the map today looks a bit primitive, as it should given its vintage, using broad approximations and based on relatively limited weather data. It also happens to be missing most of Florida and the lower parts of Louisiana and Texas.

Here is the same map with coloring hand drawn by Rehder himself.

This shading, perhaps with a crayon or colored pencil, reveals an intimate personal touch. As will be discussed later, this human involvement fortunately still exists even in developing modern day plant hardiness zones maps.

Rehder’s sweeping bands of hardiness had their origin in the work of German geographer Alexander von Humboldt

who is believed to have developed the first map with zones of equal climatic conditions, or isotherms. His first known map was published in an early world-wide atlas in 1845.

Another, even earlier, global climatic map was discovered, but it is not known if Rehder was aware of it. This map portrays isothermal bands circling around the globe and was created by

William Channing Woodbridge of Connecticut.⁹

The map appears to have been drawn around 1823 and published in 1830. Significantly, it foreshadows Rehder’s and other’s hardiness zone maps by describing bands moving through regions on the map described as Hot, Warm, Temperate, Cold, Wintery and Frozen. These early maps also are especially significant as reflecting the nascent thought that isothermal lines slice through latitudes at different angles, contrary to the then prevailing notion that climate was directly related to latitude.

However, while it may appear from the literature that after Rehder’s 1927 map the horticultural community primarily referenced updates published by the Arnold Arboretum, a significant map was published in 1928, found deep inside a dense United States government publication. The 1928 Atlas of American Agriculture, Climate. Temperature, Sunshine, and Wind published by the USDA contained climatic maps prepared by J.B. Kincer, including this map (on top of page).

While somewhat lost to obscurity, perhaps because it was just one of many maps in the publication or, unlike Rehder’s work, numbered zones were not assigned, it nonetheless appears to be the first USDA map to depict average annual minimum temperatures in zones across the United States. Even more significantly, Kincer used the measurement of the lowest recorded temperature in a year, then averaged those over a number of years, in order to arrive at the zones in the map. This differs from Rehder’s use of the average low temperatures for the coldest month, which would result in higher temperatures being used since it averaged all the low temperatures for the coldest month, instead of using solely the coldest temperature of the year. Kincer’s use of this particular measurement (referred to as the “plant hardiness (PH) statistic”) would later be adopted by the USDA when it started publishing plant hardiness maps by that name in 1960 and continues to the present.

There is not much, if any, reference in the horticultural literature to Kincer’s map after it was published. The next plant hardiness map of import published was in 1938 when horticulturist Donald Wyman

of the Arnold Arboretum enhanced Rehder’s map.

Wyman used previously unavailable temperature data from the U.S. Weather Bureau from the years 1895–1935. Significantly, he based the new isotherm contours on the average annual minimum temperatures, just as Kincer had done in 1928. Wyman’s temperature bands, however, differed by 5°F, 10°F, and 15° F, depending on the latitude. For example, average winter minimums on the map’s zone 3 range from -35° to -20°, a difference of 15°, but Zone 7 for example has only a 5° spread.

Wyman and the Arnold Arboretum continued to revise and update the plant hardiness map, including these 1948 maps, one with Newfoundland added with a taped page and another attractively colored map drawn by hand.

The above maps likely were drafts of the more polished, finalized 1948 map by Wyman and the Arnold Arboretum which incorporated new weather data.

Interestingly, in 1950 the Arnold Arboretum even placed notable arboretums and botanical gardens in the United States onto the existing plant hardiness zone map.

Wyman in 1967 published a new map, updated to reflect new weather data.

Interestingly, in 1950 the Arnold Arboretum even placed notable arboretums and botanical gardens in the United States onto the existing plant hardiness zone map.

Wyman in 1967 published a new map, updated to reflect new weather data.

Here is what appears to be a draft or working copy of the 1967 map.

… and here is the final 1967 map:

However, due to the lack of uniformity in the zone intervals in the Arnold Arboretum maps, the USDA developed and published a Plant Hardiness Zone Map [PHZM] in 1960. Dr. H.T. Skinner, the longtime Director of the National Arboretum, was chiefly responsible for the development of this map. Interestingly, Dr. Skinner worked as an intern at the Arnold Arboretum during when the first hardiness zone map was developed there in the late 1920’s.

Evidently, the introduction of the USDA map came as a surprise to Wyman. Like any other member of the public, he had to write to the USDA to request copies of the map. His 1960 correspondence reflects his having to resort to informing the USDA of his many years of having worked on the topic and that the Arnold Arboretum’s hardiness map had been universally adopted until the USDA map came along.

Wyman’s frustration with the situation comes out in a 1969 letter in which, while he refers to the USDA’s publication as a nice-looking map, he goes on to describe its shortcomings, how the new map has resulted in “farcical errors,” and how the Arboretum’s maps are really all that horticulturists need.

In an attempt to reconcile the two maps, Wyman subsequently published a table showing the differences between the two numbering systems used in his map and the new USDA map. However, the horticultural community experienced some confusion by being presented with these two different appearing maps. Despite his plaintive conclusion in the above 1969 letter of “What more can you ask” of the Arnold Arboretum’s efforts, eventually use of the USDA map increased with the USDA’s newly consistent zone designations and it became the standard for assessing plant hardiness in the United States.¹⁹

The 1960 USDA map:

Subsequently, an interesting development was reported in the May 1976 edition of the magazine of the American Association of Nurserymen. The legislature of a state, which was unnamed, was seriously considering passing a law which would make it a crime to sell plants that were “not hardy” in the region in which the plants were being sold. This proposed law was opposed by the nursery industry and ultimately not passed.

Interestingly, the magazine also included an article which provided information to the nursery industry to use in case similar legislation was proposed elsewhere. The article made the point that “hardiness” defies legal definition because of all the variables involved in the health of a plant and the geographical origin of trees or shrubs with a wide latitudinal range in nature. The existence of microclimates also complicates matters. Unusually cold winters which do not repeat themselves also are a confounding factor. The article also pointed out that at the time there were two competing hardiness zone maps in use, one from the Arnold Arboretum and one from the USDA. The map from the Arnold Arboretum had come under criticism for being compiled on too large a scale to be really accurate. Critics of the USDA map said that some of the detailing was too inaccurate and that the assignment of plants to its various zones had been on a “too short term and haphazard basis.” The article concluded that the existence of these two competing maps and the rivalry between their adherents was “eloquent testimony” to the fact that what should appear on a list of plants hardy in an area is a matter of opinion and was impossible to be legislated.

The USDA updated its PHZM (Plant Hardiness Zone Map) in 1990.

The 1990 edition of the map consisted of the average annual minimum temperatures based on the lowest temperatures recorded for each of the years 1974 to 1986 in the United States. It showed 10 different zones and introduced a zone 11 to represent areas that were essentially frost free. Almost 8,000 weather stations within the involved latitudes and longitudes for the U.S., Canada and Mexico were identified and those with valid average annual minimum temperatures based on at least 10 years of data were used.²² This also is the last USDA PHZM prepared by hand.²³

The next USDA Plant Hardiness Zone Map was published in 2012 and is shown below. It had new features, including being able to access hardiness data by zip code.

The 2012 map differs from the 1990 map in that the for the first time it was in a digital format and would be maintained on the internet. The development of the map is explained in detail in a scientifically thorough 2012 article in the Journal of Applied Meteorology and Climatology.²⁴ Highlights from the article include:

* The map focuses solely on the PH statistic, that is, the lowest temperature of each year recorded at weather stations from 1976–2005 and then averaged.

* This one dataset was used due to its widespread adoption both in the United States and internationally. As the article notes, “Accurate prediction of winter injury is a key component to the successful cultivation and survival of long-lived woody and herbaceous perennial plants in many regions of the world. The frequency and severity of winter injury are also important determinants in the natural distributions of many temperate plants.”²⁵

* Instead of the 13-year data set used for the 1990 map, the 2012 map included 30 years’ worth of data. This longer period of time was chosen because “… it was more stable statistically, samples recent climatological variation more completely, and yields a clearer picture of the role that past winters have played in the survival of long-lived plants.”²⁶

*An interesting glimpse into climate reports reveals that the weather station data used is incomplete, but this evidently is acceptable (with limitations) in the meteorology field. Most of the weather stations in the country are referred to as “COOP” stations, which are stations operated by volunteers, typically at most only record findings once a day and not unusually are missing a significant number of weather observations throughout a year. There exist other weather stations, but far fewer in number, which are operated or monitored by professionals, record observations hourly, undergo more rigorous quality control checks and are not known to have missing information. The following are images of the COOP station in Cary, NC which sits in someone’s neighborhood front lawn, a weather station in someone‘s backyard in Falls Lake, NC, the model of which can be bought online at Amazon, and a photograph of the “First Order” type professionally maintained weather station at the Raleigh-Durham Airport in North Carolina.

*The quality threshold for weather stations to be used in development of the 2012 map was that they had to have at least 24 days of minimum temperature data during each of the months between October and March for at least 10 of the 30 years involved in the study, and they were then put through other quality control procedures. So, otherwise stated, a weather station missing 20 percent of its relevant weather data and for as much as 66 percent of the time-period involved would still be used.

*This is not necessarily a criticism of this methodology, but more of an insight afforded to gardeners into how climate statistics are derived. Of the 7,983 weather stations used in developing the map, only a small portion are professionally operated or monitored with consistent recording of observations. Nonetheless, the 2012 map clearly is significantly more sophisticated than prior maps and the result of use of updated, modern technology.

* Despite the use of advanced technology, the human element remained in the formation of the 2012 map. As explained by the USDA, once an initial draft of the map was produced, people from the agricultural, climate and horticultural communities were able to comment on whether certain parts of the map were too warm or too cold in their opinions, and changes were made based on this human input.²⁷ While not the same as colleagues gathered around the drafting table while the 1927 and 1928 maps were drawn up by Rehder and Kincer, it nonetheless is reassuring to see the human touch involved.

* It is important to keep in mind that the 2012 map reflects the average lowest winter temperature for a given geographic area for this 30-year period but does not necessarily represent the coldest it has ever been. This would be due to data from prior to 1976 not being included and because many of the weather stations used have missing days of data.

* The USDA plant hardiness map is not an indicator of whether global warming/climate change is occurring. The USDA states, “Climate changes are usually based on trends in overall average temperatures recorded over 50–100 years. Because the USDA PHZM represents 30-year averages of what are essentially extreme weather events (the coldest temperature of the year), changes in zones are not reliable evidence of whether there has been global warming.”²⁸ The founder and director of Oregon State University’s PRISM Climate Group, which per contract with the USDA created the 2012 map, also commented, “Plant hardiness is ‘a really volatile statistic in time. It’s only one day per year over 30 years. Even if the average is slowly creeping up on us, as a single, volatile statistic it’s just not a very good metric for looking at climate change.’”²⁹

*Even though the data in the 2012 map is as of 2005, the USDA reported that a check of more recent data did not find that adding the more recent years of data would make a significant difference in the definition of the zones.³⁰

WAKE COUNTY, NORTH CAROLINA

As this piece was originally written and published in 2020 in the state capital of North Carolina, Raleigh (Wake County), a brief note is made about its plant hardiness zone status. Wake County for decades lived in the Zone 8, 10–20° average annual minimum temperature zone, starting with Kincer’s USDA map of 1928 and in the succession of Arnold Arboretum maps. Wake County continued to reside in this Zone 8 through the USDA map of 1960, where it was within Zone 8(a) until 1990. However, it was placed into Zone 7(b) (5–10°) in the USDA maps of 1990 and 2012, where it predominantly remained until 2023.³¹ So, whenever the USDA map was to be next updated Wake County may find itself in Zone 7(a), still primarily in Zone 7(b), or Zone 8 may come back to all or most of Wake County, where it previously was for over 60 years, from 1928 until the 1990 USDA map was published.

2023 Update

The USDA issued a new Plant Hardiness Zone Map in November 2023, which can be accessed at this link:

https://planthardiness.ars.usda.gov/

This is an image of the new map:

Recall that the last map was issued in 2012 and based on weather data from 1976–2005, while the new 2023 map is based on data from 1991–2020, the data still being the lowest single temperature each year for 30 years and then averaged. The map was created by the same PRISM Group at Oregon State University which developed the 2012 map, using similar methods for the 2023 map (although including more weather stations), so the above observations regarding this process (for example, quality of data and weather stations) would still be applicable.

The new zones can be found either by way of zip code entry or viewing a high-resolution map. It appears that many North Carolina counties have been redesignated half a zone up. For example, While Wake County in the 2012 map was mostly zone 7b (temperature range of 5°-10°) with spots of zone 8a (10°-15°), in the new map Wake County has returned to being in zone 8 (8a) where it previously had been from 1928 until the 1990 hardiness zone map. A comparison of the new map with the maps from earlier times (see above) reflects that most, if not all, of the counties in North Carolina have returned to their prior zone designations from the 1928–1990 period. A glance at other parts of the country bears this out as well.

The USDA again cautioned that because the new map represents only 30-year averages (instead of 50–100 year averages) of what are essentially extreme weather events occurring on a single day, that is, the coldest temperature of the year, “changes in zones are not reliable evidence of whether there has been global warming.” Additionally, in addition to the temperature data collection, zone changes also resulted from additional data sources and improved numerical analysis methods.³²

The USDA also reiterated that the hardiness zone maps are only a guide and that what has thrived in yards will most likely continue to thrive and that, “No hardiness zone map can take the place of the detailed knowledge that gardeners learn about their own gardens through hands-on experience.”

This cautionary language comes into play if one reviews the actual minimum temperatures occurring in an area. For example, in Wake County, in the past 30 years from 1993–2022, in nine different winters, including as recently as 2022, the minimum temperature was 10° or less, in other words, zone 7b, 7a (0°-5°) and even 6a (0°- minus 5°) temperatures. These nine minimum temperatures were 0°, 1°, 2°, 4°, 7°, 7°, 9°, 10° and 10°.³³

One well-known local nursery owner recently found that according to temperature readings on his property in Wake County, there have been six winters during the most recent 30-year dataset when temperatures dipped below the minimum 8a temperature threshold. “Since the purpose of the map is to show people what they can grow in each zone, this is troubling,” he noted. He pointed out this means that for those gardeners who may have planted based on a minimum zone 8a, instead of 7b, they would have lost their plants every five years.³⁴ This would happen even more often using the other Wake County minimum temperature figures noted above.

Realistically, many gardeners do not research the history of minimum temperatures in their area and will rely just on whatever zone is listed next to a plant description at the nursery or online. Perhaps someday the USDA will be able to incorporate this minimum temperature information into at least their online maps. A couple of possible ways include including the percentage of years with “subzone” minimum temperatures from the prior 30 years, or even coming up with a new 30-year average by decreasing the average low temperature from the prior 30 years by that same percentage. In any event, until then what the zones in one sense mean is that the odds are with the gardener, but only for an unpredictable number of years, if he or she plants, for example, an 8a minimum plant in zone 7b, but there likely will come a reckoning when the plant at some point will be killed by a “below zone” minimum temperature freeze or at least extraordinary measures will need to be taken to protect it.

Gardeners are well advised to learn about minimum temperatures in their area before making planting decisions if these below zone temperatures would result in a particular plant meeting its demise. A reasonable approach may be for gardeners to plant by the rule of always planting at least one zone below their designated hardiness zone in order to avoid the scenarios described above.

By Tom Packer, Past-President of the Gardeners of Wake County, Board Member of the North Carolina Cooperative Extension Agricultural Programs Foundation, North Carolina State Cooperative Extension Certified Master Gardener Volunteer of Wake County (Chair of Management Team and Gardening Helpline), longtime backyard farmer in North Carolina and Northern California and BA and JD from the University of California. This article formed the basis for Mr. Packer’s invited presentation on the history of our plant hardiness zones at the 2025 International Master Gardeners Conference. Mr. Packer can be reached at tpacker25@outlook.com. All this article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated.

_________________________________________________________________

[1] Monrovia.com and https://drive.google.com/file/d/1ZYAc7dsGo2_vl92HtR4a1FeH_6hXSj48/view?usp=sharing

[2] Wyman, Donald. “A HARDINESS MAP FOR THE UNITED STATES.” Bulletin of Popular Information (Arnold Arboretum, Harvard University), vol. 8, no. 12, 1940, pp. 61–64. JSTOR, www.jstor.org/stable/42962115; https://drive.google.com/file/d/1z-8_6wBNGnpPiMv3e4LD7-u-Ex9fGxDQ/view?usp=sharing. Accessed October 4, 2020, or see: https://drive.google.com/file/d/1HuBqHMcDLkGbCTAHmKVLxKhI8S2crXU2/view?usp=sharing

[3] Daly, C., M.P. Widrlechner, M.D. Halbleib, J.I. Smith, and W.P. Gibson. 2012. Development of a new USDA Plant Hardiness Zone Map for the United States. Journal of Applied Meteorology and Climatology, 51: 242–264 at 259: https://drive.google.com/file/d/1BvgfTSOw7F3uEgoM_Jw1x7DG0A-18vUo/view?usp=sharing

[4] https://www.almanac.com/content/plant-hardiness-zones# and https://drive.google.com/file/d/10fG40HTS9pjfWYV9zVL3rActf4BDnqRm/view?usp=sharing

[5] https://www.flickr.com/photos/usdagov/6862204426/in/photostream/

[6] Image courtesy of Arnold Arboretum Archives

[7] Image courtesy of Arnold Arboretum Archives

[8] System Der Isotherm-Kurven in Physikalischer Atlas. Heinrich Berghaus, 1845. Image from Geography and Map Division, Library of Congress

[9] https://en.wikipedia.org/wiki/William_Channing_Woodbridge

[10] Isothermal Chart, or View of Climates & Production in Woodbridge’s School Atlas to Accompany Woodbridge’s Rudiments of Geography: Atlas on a New Plan . . . William C. Woodbridge, 1830. Geography and Map Division, Library of Congress. See also, https://blogs.loc.gov/maps/2018/04/the-first-isothermic-world-maps/ and https://drive.google.com/file/d/1IMPz5OYOMkmxucrhqE1uKrGgCPGDSEEp/view?usp=sharing

[11] https://archive.org/details/CAT31378527007/page/n17/mode/2up See, p. 10.

[12] Image courtesy of Arnold Arboretum Archives

[13] https://www.flickr.com/photos/usdagov/7008319727/in/photostream/

[14] Image courtesy of Arnold Arboretum Archives

[15] https://www.flickr.com/photos/usdagov/7008320087/in/album-72157627857689389/

[16] Image courtesy of Arnold Arboretum Archives

[17] Image courtesy of Arnold Arboretum Archives

[18] https://www.flickr.com/photos/usdagov/7008320087/in/album-72157627857689389/

[19] Daly, C. (n 3) at 259

[20] https://www.flickr.com/photos/usdagov/7008290183/in/photostream/

[21] https://www.flickr.com/photos/usdagov/6862173684

[22] United States Department of Agriculture, Agricultural Research, Miscellaneous Publication №1475

[23] Daly, C. (n 3) at 243

[24] Daly, C. (n 3)

[25] Daly, C. (n 3) at 242

[26] Daly, C. (n 3) at 244

[27] https://drive.google.com/file/d/1PdH0jd1rgcnBRH4KVdA0Mv6oQAMekNC8/view?usp=sharing and http://web.archive.org/web/20201202061642/https://planthardiness.ars.usda.gov/PHZMWeb/About.aspx

[28] https://drive.google.com/file/d/1MA7gw5GgsVCusiA8JwzZaUqvsFqRN6AV/view?usp=sharing , http://web.archive.org/web/20201114005450/https://planthardiness.ars.usda.gov/PHZMWeb/AboutWhatsNew.aspx and https://planthardiness.ars.usda.gov/pages/map-creation#:~:text=Climate%20Change,been%20global%20warming.

[29] https://www.wiscontext.org/where-wisconsin-do-hardiness-zone-shifts-reflect-changing-climate and https://drive.google.com/file/d/1N0DcJHMkzhPwUyEky7DMFn-OapXf1N2p/view?usp=sharing

[30] https://drive.google.com/file/d/1MA7gw5GgsVCusiA8JwzZaUqvsFqRN6AV/view?usp=sharing and http://web.archive.org/web/20201114005450/https://planthardiness.ars.usda.gov/PHZMWeb/AboutWhatsNew.aspx

[31] https://drive.google.com/file/d/17lXEDuy5lA9Kv-qz5cpj6DXhTiDm7bfK/view?usp=sharing and What’s New | USDA Plant Hardiness Zone Map (archive.org). Focused viewing of an enlarged Wake County on the USDA interactive online map reveals some thin shaded areas in the color representing zone 8(a) along its southern and southeast borders and a few small, isolated areas (one being where a large, local shopping center is located) elsewhere. Interestingly, however, there are no, and never have been any, reporting weather stations in these areas. Moreover, the listing of plant hardiness zones by zip code by the PRISM Group reflects that all zip codes in Wake County on the 2012 map are designated as being in zone 7(b). See, CONUS ZIP Code Listings at https://prism.oregonstate.edu/projects/plant_hardiness_zones_2012.php. Inquiries about this issue to the USDA’s designated email address for questions about the hardiness zone map did not receive a response.

[32] https://planthardiness.ars.usda.gov/pages/map-creation and https://drive.google.com/file/d/17OQJB13MhECetKGJBaPAqX8Ib7BIFmUW/view?usp=sharing

[33] http://xmacis.rcc-acis.org/ : single station/seasonal time series/ min temp/minimum/ 1993–2022 / Station: Raleigh Area/ RDU

[34] https://drive.google.com/file/d/1njK2tB_675UpoYoKoim-S9cVTKjTVr0-/view?usp=sharing

Once there was a world without weeds. Then, there were … weeds. This is a review of the arc of development of weed control from the earliest time period when there was no such thing as a weed, to primitive attempts to deal with these competitors to humans’ early attempts at agriculture and then through the rigorous examination of how best to deal with weed problems in Britain and Ireland which ultimately found its way to America.

Present day weed control typically is presented under the framework of “Integrated Weed Management” and there are very well-respected Weed Science programs at major universities throughout the world. While farmers and gardeners as recently as two or three generations ago struggled to find information on weed control techniques, much has been written on the subject in the past several decades and exhaustive resources are now available on the internet and through cooperative extension programs in many states.¹

Integrated Weed Management typically is expressed as involving four methods of weed control: Cultural, Mechanical, Biological and Chemical.

Cultural control employs horticultural methods and practices to control weeds. For example, growing rows of lettuce close to each other serves to deprive the soil underneath of sunlight which inhibits the growth of weeds.

Mechanical control is the most direct way to rid land of weeds as it basically involves physically removing them by hand or tool. However, care needs to be taken not to revert to historical inefficiencies as exemplified by this Youtube video which takes 2 minutes and 14 seconds to demonstrate how to remove a single weed by hand:

As will be discussed in more detail below, mechanical control of weeds was the predominant method throughout much of history, leading to use of human labor at the sacrifice of higher utilizations and purposes, for example, children laboring in fields instead of attending school.

Biologic weed control is the one method which has not changed much over the years as it essentially involves using animals to control weeds.

Chemical weed control greatly expanded in the 20th century and this article winds up at the dawn of that modern development about 100 years ago. However, primitive forms of herbicides were used centuries ago, foreshadowing the need and utility of weed control methods which were effective in terms of cost, time and labor.

So, let’s start at the beginning. When humans were in our stage of development of being hunters and gatherers, that is, pre-agricultural, there was no such thing as a weed. In other words, a “weed” is a human construct in that what grew out of the ground was really of no concern as certain unwanted plants were not competing with desired plants under cultivation, since cultivation was not yet occurring at the time.

A review of literature reveals that the concept of a weed, or unwanted plant, came about, at least according to biblical writings, when Adam was promised thorns and thistles…

and Jonah became tangled in water weeds on his way to his experience with the whale.²

Further found in preserved ancient biblical literature was the Parable of the Tares:

‘The kingdom of heaven is like a man who sowed good seed in his field; but while men slept, his enemy came and sowed tares among the wheat and went his way. But when the grain had sprouted and produced a crop, then the tares also appeared.

“‘So the servants of the owner came and said to him, “Sir, did you not sow good seed in your field? How then does it have tares?” He said to them, “An enemy has done this.” The servants said to him, “Do you want us then to go and gather them up?”

“‘But he said, “No, lest while you gather up the tares you also uproot the wheat with them. Let both grow together until the harvest, and at the time of harvest I will say to the reapers, ‘First gather together the tares and bind them in bundles to burn them but gather the wheat into my barn’”’” (Matthew 13:24–30).

Indeed, it is very difficult to distinguish between the tares weed and a shaft of wheat:

However, it is generally thought that the first stabilized agriculture came about near the Euphrates and Tigris rivers in Mesopotamia and the Nile River in Egypt about 6,500 B.C.

Along the way in the B.C. years, here is an example of a hand sickle which came into use, although probably just for harvesting purposes:

By 1000 B.C. there is evidence of more agricultural tools being developed such as this drag harrow formed from a tree limb with short stubs of branches for tilling, then an A-shaped log with wooden pegs to form teeth and even later adding a collar so that an animal could pull the device — but still no mention in the ancient B.C. literature about such tools being used to remove weeds.

By the first century A.D. Roman writers were beginning to mention the deleterious effect of weeds on planted crops and describing various metal-bladed tools for agricultural purposes, such as the these:

Burning of crop stubble also was taking place, in part to destroy leftover weeds.

Olive oil, tree pitch and grease also were noted in the first century A.D. as harmful to seeds, but not yet referencing use to destroy weeds. One early agent of an herbicidal nature was mentioned in the first century A.D. namely, “amurca,” the liquid residue after oil was drained from crushed olives. A first century writer noted that amurca was poisonous to weeds as well as to ants and moles. Where amurca flowed from the oil presses onto the fields the ground became barren so that, “ … it is usually poured around the roots of trees, chiefly olive trees, and wherever noxious weeds grow in the fields.”³ Whether it was an agent from the olive juice itself, or perhaps as a result of salt added to the process is not entirely clear, but by all accounts the use of amurca is an example of one of the first herbicides.

One biologic method of weed control, however, had evolved in Asia, with grass carp controlling unwanted vegetation in rice paddies.

But, generally, for most of post-agricultural history weeds were a burden and a curse to be endured and about which not much could be done except by laborious hand methods. Available literature from the first 1,000 years or so A.D. suggest that other agents were used to kill unwanted plants including salt, a mixture of salt and duck excrement, mixtures of herbs and salt and even preparations involving human feces. While salt was leaned on as an herbicide, it generally was unsatisfactory as it dissolved and ran off when wet and was thus a threat to desired plantings, but along the way people came to only drop it only on the crowns of thistles, use over gravel paths, apply to fallow land in the Fall and mix certain amounts with seed. Nevertheless, physical labor remained the primary methods of removing weeds.

One of the first regulations concerning weeds to be found was a law in Scotland from 1212–1249 which had severe penalties to tenants who seeded weeds on land or who did not destroy certain weeds. Enforcement was reportedly so effective that the region became known for grains free from weed seeds and sheriff’s enforcers were noted not to be able to find enough weeds to collect their fines.

Eventually, as literature and the arts began to expand, references to weeds began to appear more frequently.

“Who weeding slacketh, good husbandry lacketh.”

Poetic agricultural writer Thomas Tusser, 1557

Shakespeare even used weeds as a pejorative prop in his plays:

… I will go root away

The noisome weeds, which without profit suck

The soil’s fertility from wholesome flowers.

- Richard II, Act III, Scene 4

Also, who can forget King Lear and his crown of weeds?

One agriculturist rose to prominence in the 1700’s in England and who ended up having a great influence on many horticultural issues of the day, including weed control. This man:

… who turned out to be the inspiration for this English rock band’s name:

The 4th edition of Jethro Tull’s “An Essay on the Principles of Vegetation and Tillage,” as well as other writings, reflect him putting a bullseye on the back of weeds and making them public enemy №1.⁴ This excerpt is an example of his emphatic message in this regard:

Mr. Tull’s ideas and creations have been said by some to have been a basis of the British Agricultural Revolution. His most well-known invention was the grain drill, which for the first time planted grain crops in straight rows, whereas previously seeds were scattered by hand over plowed fields. This later would cause great problems while attempting to weed the fields as the weeders had a difficult time making sure they were weeding the weeds and the not the crop (which also reflected that not much had changed in weed management from the time of the Parable of the Tares). Having all of the crop seed in rows meant any plant life outside of the rows was a weed. It also allowed Tull’s cultivation tool consisting of a horse-drawn harrow to be used between crop rows to loosen the soil between the drilled rows and to physically kill weeds. He also developed a horse-drawn hoe which dug out roots and grasses from the ground which were tossed to the side to dry and die.

Here is an image of a drawing of his ground-breaking grain seed drill invention:

Illustrators of plants also began to recognize individual weed plants, even in 1771 portraying them as objects of beauty.⁵

1806 saw one of the first writings which discussed specifically the subjects of weeds in the garden, not just out in the fields on a farm.⁶

This publication used the word “extirpation” by way of describing what farmers and gardeners desired to do to weeds, with extirpation defined as “to destroy completely” or “pull up by the root.” This signals an increased use of direct and aggressive language used by those describing methods of weed control. As will be seen, terms such as “destroy,” “kill” and “bleed to death” are used. The phrase “Integrated Weed Management” or other such euphemisms are nowhere to be found in the horticultural literature of the 18th or 19th centuries. It can be imagined that Jethro Tull and his cohorts may very well have reacted to such as a term by imploring the user not to be so indirect and to stop beating around the bush so to speak, but, rather, to clearly express the necessary actions to be taken against such a pernicious interloper. Perhaps “extirpation” was the Integrated Weed Management of its day, although it expresses such a deadly goal in such an elegant way that perhaps its use should be resuscitated, maybe with academic degrees in Weed Extirpation being awarded instead of Weed Science — after all the whole purpose of weed science, integrated weed management and the like is to kill, destroy, indeed to extirpate, weeds.

In the above report, Mr. William Pitt of Wolverhampton, England succinctly sets forth the prevailing view of weeds:

He goes on to compile a list of 22 different types of weeds which he describes as “… the principal intruders into the garden.” He then counsels gardeners to pull up weeds before they seed and states that, at least in Staffordshire, the principal tools used in the garden for “destroying” weeds are the spade, the three-fanged fork and various hoes.

Ways to extirpate weeds and how to communicate and educate on the subject became a more frequent topic during the British Agricultural Revolution as reflected by this publication:

Within this Essay on the Weeds of Agriculture, a letter from a farmer is summarized as follows:

So, it is known at least by the early 1800’s there still did not exist a preeminent text which advised farmers and gardeners on methods of killing weeds. Mechanical, cultural and biologic methods still ruled the day, with advanced herbicides about a century away, although as will be seen crude attempts at using chemical herbicides were under way.

Nonetheless, a general mood of not being able to control the presence of weeds prevailed, leading some countries and local governments to pass very rigorous weed control laws. Ireland, for example, in 1860 passed a national law which allowed a landowner to give notice to any adjoining property owner to cut down and destroy weeds on the property. Some present-day local HOA regulations have nothing over the Irish as the adjoining landowner then had 14 days to extirpate the weeds or be subject to a stiff financial penalty; or the local Justice also could issue an order allowing the property owner to go onto the land and remove the weeds himself. Here is the printed cover page of the law.⁷

The war on weeds in Ireland, and elsewhere, was eloquently declared and set forth in an extensive report in the 1875 “Agricultural Statistics, Ireland” which contained a detailed “Appendix Containing Information Regarding the Extirpation of Weeds.”⁸ The report first noted the “lamentable” prevalence of weeds in Ireland and that “several Grand Juries have given directions to the County Surveyors to take all necessary steps to prevent the great injury to the farming classes which has hitherto arisen from the growth of weeds along the sides of public roads.”

So, what means did Ireland then employ to attack this lamentable problem?

That’s right, children. The Commissioners of National Education were told to instruct the country’s teachers to direct the attention of the school children to the importance of destroying weeds when found growing on their parents’ farms. Religious school leaders as well as heads of workhouses also were brought into this effort to deploy children across the Emerald Isle in an effort to extirpate weeds. An example was given of a farmer who paid local children to collect weeds and add them to a heap of weeds and other plant refuse which would burn continuously for weeks at a time, with the ashes then later used as a soil amendment. The particular essay describing this process concluded by noting, “Always destroy the life and reproductive power of weeds, even by fire, if necessary.”

This fascinating and eloquent appendix did not stop there, however. It then continued to enlist the writings of this, as he was described, “most observant and popular author(s)”:

Yes, even Charles Dickens had something to say about eradicating weeds, and he did not mince his words in literally declaring war on weeds in a periodical of the time:

The Appendix concludes in a very articulate and impassioned manner by noting that “as far as weeds are concerned, Ireland is the wealthiest country in the world” and the “evil is almost universal.”

Nonetheless, artists continued to illustrate in very detailed and appealing ways plants known as weeds.⁹

By the late 1800’s the aggressive approach to weeds seen in Europe made its way to the United States. One letter to the Editor of Science magazine in 1892 from someone at an “Experiment Station” in North Carolina suggested several definitions he had found for weeds.

He added that his own definition of what constitutes a weed is, “Any plant which from its situation or inherent properties is hurtful to human interests; a vegetable malefactor.”¹⁰

Then in 1892 a bulletin from a West Virginia Agricultural Experiment Station reflected the still predominant use of mechanical means of addressing weeds in the United States, while discussing the nascent use of forms of herbicides. The bulletin referenced a poll taken of growers and reported the use of salt but concluded that it must be used in great quantity and was useful only in very limited areas. Lime was meeting with only limited success. The use of coal, oil or kerosene was not recommended as it was too costly and only effective when poured generously upon small areas of soil. While sulphuric acid was noted to kill any weed, it had to be applied directly to each individual rootstock, thus rendering the process a tedious and costly one. The bulletin concluded, “Experience and experiment have conclusively proven that any extended use of chemicals as weed killers is always attended by more expense and labor than the results can possibly compensate for.”¹¹

An 1897 report from the United States Department of Agriculture listed America’s “Twenty-Five Most Harmful Weeds” and how to control and eradicate them. Among the suggestions are frequent hoeing or spudding, continued cultivation, use of coal oil or carbolic acid, thick seeding with smothering crops, mowing before flowers open, burning mature plants, salting the plants and pasturing sheep on them, hot brine, kerosene, hand pulling, use of clean seed, application of lime to acidic soils to stimulate grass and clover and plowing to expose rootstocks to frost or hot sun.

By the turn of the century, in 1905 the USDA was not mincing words:

Jumping back across the pond, a look at a 1910 English publication, “Common Weeds of the Farm and Garden,” reflects Europe’s evolving approaches. Various planting and cultivation strategies still were recommended, as were use of various tools. However, there were additional stratagems including better methods of irrigation to help crops grow stronger and more widespread, draining water from low-lying areas, use of large sheets of tarred paper to block light, and use of sand mixed with sulphate of ammonia on lawns and spraying plants with poisons such as sulphate of copper and carbolic acid. Interestingly, children were still regarded as a means of weed extirpation as it was recommended that prizes be offered to them to collect certain types of weeds.¹²

This discussion leads up to the time of discovery and use of modern herbicides which would thereafter dominate the weed science literature. While it is noted above that a manual on how to control weeds was not yet available in the early 1800’s, such publications became available around the turn of the century. The 1919 publication of the “Manual of Weeds” by Ada Georgia of Cornell University provided a definitive treatise on weeds in America and how to destroy them.¹³

The manual starts off by defining a weed as “… a plant that is growing where it is desired that something else shall grow. It follows that a plant may be a weed in some places and not in others.” The manual then discussed various mechanical and cultural approaches to weed control including this illustration of various tools used for destroying weeds.

Some of the principles of weed destruction listed included not allowing weeds to ripen to seeds, killing weeds while in the seedling stage, never plowing under weeds bearing mature seeds, using grazing animals — particularly sheep, and rotating crops. The manual then discussed the “comparatively new” way of fighting weeds, namely use of chemical herbicides, although it cautioned that further experimentation was necessary. The manual references field trials in South Dakota applying chemicals to weeds which were the first of their kind in any country. In addition to the types of chemicals mentioned in the above 1910 article from England, bichloride or mercury, kerosene, crude petroleum and arsenate of soda also were mentioned as promising chemical agents for weed extirpation.

Lastly as a new era in weed control began in the 1920’s, this article will end with a USDA publication of that time which exemplifies one of the original points made at the beginning of this article, that is, that weeds at first were, and always have been, a human construct. The following USDA Circular 89 from 1920¹⁴ extolls the virtues of a plant which thrives well in the eastern half of the United States, was regarded as an “excellent vine for arbors and porches” and “for which purpose it is commonly cultivated in most Southern cities.” It also was noted to be a useful grazing and forage crop and a cost-effective substitute for hay. This wonder plant?

Of course, years later Kudzu was being described as the “Vine that ate the South” with the reputation of the fastest and most invasive growing vine in the United States.

It so far has eluded extirpation and remains an Herba (grass) Inutilis (unprofitable, useless, worthless, disadvantageous, harmful, inutile).

By Tom Packer, North Carolina State Extension Certified Master Gardener, Past-President of the Gardeners of Wake County, Board Member of the North Carolina Cooperative Extension Agricultural Programs Foundation and longtime backyard farmer in North Carolina and Northern California. All this article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated.

___________________________________________________________________

ENDNOTES

[1] See for example North Carolina State University’s comprehensive weed control site: https://gardening.ces.ncsu.edu/weeds/

[2] Acknowledgment is given to the following sources of information from which this article quotes, summarizes, references text and ideas, and derives inspiration:

- https://wssa.net/wssa/weed/education/antique-literature/: This is a unique collection of ancient literature on weeds and weed management gathered by Dr. John D. Byrd, Jr. of Mississippi State University and maintained on the website of the Weed Science Society of America.

- Smith, Allan E. and D. M, Secoy, “Forerunners of Pesticides in Classical Greece and Rome.” J. Agric. Food Chem., Vol. 23, №6 (1975). https://www.hort.purdue.edu/newcrop/Hort_306/reading/Reading%2018-1.pdf

- Smith, Allan E., and D. M. Secoy. “Early Chemical Control of Weeds in Europe.” Weed Science 24, no. 6 (1976): 594–97. http://www.jstor.org/stable/4042614.

- Timmons, F.L., “A History of Weed Control in the United States and Canada.” Weed Science 53, November-December 2005: 748–761, originally published in Weed Science 1970, 18(2):294–307. http://www.jstor.org/stable/4046973

[3] See, endnote 2, Smith, Allan E., and D. M. Secoy. “Early Chemical Control of Weeds in Europe” at 594.

[4] https://wssa.net/wp-content/uploads/antique/Tull_Horse%20hoeing%20husbandry.pdf

[5] Blackwell, Elizabeth. 1771. “Cotula faetida (May-Weed or Faetid Camomile)

[6] https://wssa.net/wp-content/uploads/antique/communicationsvol5.pdf

[7] University of Southampton. Bill to Provide for Destruction of Weeds in Ireland. Documents. HMSO, 1860. https://jstor.org/stable/community.29942810.

[8] University of Southampton. General Abstracts of Acreage under Crops, and Live-Stock, 1875 (Appendix Regarding Extirpation of Weeds) and General Abstracts of Emigration from Irish Ports, January-July 1874 and 1875. Documents. HMSO, 1875. https://jstor.org/stable/community.29941883.

[9] Millspaugh, Charles Frederick. 1887. “Ambrosia artemisiaefolia” (Common Ragweed)

[10] McCarthy, Gerald. “American Weeds.” Science 20, no. 493 (1892): 38–38. http://www.jstor.org/stable/1768173.

[11] https://wssa.net/wp-content/uploads/WVAES_1892_Distribution-of-weeds.pdf

[12] https://wssa.net/wp-content/uploads/antique/Long%201910%20Common%20Weeds%20of%20the%20Farm%20and%20Garden.pdf

[13] https://wssa.net/wp-content/uploads/antique/Bailey_1919_A%20manual%20of%20weeds.pdf

[14] https://wssa.net/wp-content/uploads/kudzu89pipe.pd_.pdf

I participated in the 2020 census — did you? So why not conduct a census of your garden?

We bought our house in Raleigh, Wake County, North Carolina about 10 years ago this Fall, and with it front, back and side yards on a third of an acre. We inherited a yard dating back to the mid-1950’s consisting not just of lawns and plant beds, but old, well-established borders busy with plant life. It was not until the next Spring and Summer that it all started to grow out, with many kinds of vines, ground cover plants and strange (at least to me) looking shrubs sprouting to life. While trying to tame the growth and planting things of our own, I eventually wanted to know exactly what was growing on and in our land. I also wanted to record what I had planted in order to remember and better keep track of our plantings.

I embarked on researching the best way to go about creating an inventory, or census, of our garden plantings. I looked into some programs and apps which allow one to create a garden map and list plants. There are several out there on the internet if you just use search terms such as “garden planner” “garden map” and the like. No cost programs such as “Garden Planner Online,” “Plan-a-Garden,” and “Garden Visualiser” will pop up. A fellow gardener highly recommended the Garden Planner at jungseed.com. I also closely looked into a program at smartdraw.com which is a very elegant, professional grade diagramming and charting program for which a license must be purchased. I almost took the plunge but found the tech requirements a bit too daunting. I am a Microsoft Office Windows user with a SurfacePro laptop.

After all this, I concluded that what I really was searching for was something simple, easy to use, but which could be updated and maintained on my laptop so that I literally could carry it out to the garden and point out which plant was which. I had in my mind electronically keeping the equivalent of a paper notebook, but which I could revise as plants come and go, and also make care and maintenance notes for any plant or area of our yard.

So, here is the process by which I came to develop what I think is a user friendly, workable way of keeping track of everything in a garden. Although it involves my use of Microsoft friendly products, the same principles apply and are easily transferrable to Apple or other programs.

First, I found a survey map of our property and divided it into 15 hand-drawn plots which made the most sense to me. For example, our pollinator garden, which is busy with numerous plants, was Plot 1 and our front lawn with persimmon tree was Plot 11. I then scanned it and saved it on my computer. If you do not have a formal map of your property it is easy enough to draw one yourself, or some counties have property maps accessible online, for example Wake County, NC at City of Raleigh and Wake County iMAPS (raleighnc.gov). Overhead images are available via Google Maps satellite view. You just do not want the plots you draw to become too crowded as you will be inserting numbers within the plots, representing each plant that resides in that plot. See my map just below and here.

I then learned how to use Autodesk SketchBook.

which turned out to be remarkably easy and is free to boot.

I created and saved 15 different documents on SketchBook, one for each of the 15 plots drawn on my map, and labeled them #1, #2, and so on.

I then drew the outline of the plot. You can use either a computer pen or stylet

or a mouse to draw.

I used both, depending, but usually preferred the pen.

Then came the challenging, yet fun, part of identifying the plants. How many times have you stuck a plastic plant tag in front of a new plant in your garden, only to have had it disappear whenever you much later bend over to remind yourself of the plant’s name? Identifying some of the plants was easy, but there was a combination of those previously planted by the prior owners, wild volunteers and those that I planted but whose names I could not recall — I referred to them as the “unknowns.” I primarily relied on smartphone apps to identify the “unknowns.” I tend to rely primarily on Google Lens, but other apps I have used include Plant Snap and iNaturalist, and of course there are more out there. On some of the more unfamiliar plants, I ended up having debates with myself over which image and name was the correct one, and sometimes admonishing myself that it was not really necessary to work my way down the entire taxonomic hierarchy of the plant. Eventually after a fair amount of bending over, taking pictures and online sleuthing, I came up with names for what I believe are all plants other than weeds growing in our yard. Of course, this is best done in Spring, Summer or early Fall when everything is grown out.

Once the plants in a plot were identified, I then typed them into a Word document under headings for each plot and assigned a number to each. I then drew the numbers into the plot, approximating where each plant was located. Here is an example of one of the plots, #1. All the plots can be viewed here.

This particular plot is busy with numbers as it is the pollinator garden, filled with many different and unusual types of pollinators. As an aside, many of these plants were picked up at the JC Raulston Arboretum in Raleigh which has a Plant Buggy in front of its visitor center where interesting and unusual plants can be found and purchased, typically for $5.00.

Here is a link to the Word document I prepared which lists all the plants in our yard. If you look at Plot 1 at the top of the document, you will see all the above plants listed, 1–19. Note: I recently pulled out plant #17 but will replace it on the list once another plant goes back into its place. Or, I could just erase on the SketchBook page numbers 18 and 19 and turn them into numbers 17 and 18.

The individual notes about various plants have been removed to avoid clutter, but here is one for the three gardenia plants in Plot 4 as an illustration:

Plot 4:

…

6 — Gardenia

- Prune to shape after Fall bloom

- Early Spring and Fall — add Epsom Salt/magnesium supplement

Pretty straight-forward, but that sums up what I think I need to do to keep our gardenias healthy and looking good, unless a spray comes to be needed to deal with a fungus. I have calendar entries on the 15th of each month in my Outlook calendar in which I list the various tasks to be done in the garden that month and they are set on an annual recurring basis so that they pop up each year. For example, the above note to prune my gardenia after the Fall bloom appears in my October 15th calendar entry and the magnesium supplement appears in my September 15th and April 15th entries.

By the end of this process, I discovered that I have more than 100 different types of plants growing in our yard, many of which naturally appeared over the years or were planted long ago by someone else. I think it gives a gardener a sense of place and a feeling of control and supervision of our immediate environment. At the very least though, as our garden lives and evolves, we can now keep track of and care for everything living thing, which we now know by name. If someone asks me the name of a plant, I just identify the plot, locate the number within the plot and then find that number on the list of plants.

Good luck with your garden census!

By Tom Packer, Certified Master Gardener, Immediate Past-President of the 85-year-old Gardeners of Wake County Garden Club and longtime backyard farmer in North Carolina and Northern California. All this article’s content is that of Mr. Packer alone as an individual and not as a member of or on behalf of any organizations or groups with whom he is affiliated.