By David R. Legates

A recent article in The New York Times described a major report issued by the National Academies of Sciences, Engineering, and Medicine. The report detailed that carbon dioxide, methane, and other planet-warming greenhouse gases are threatening human health. Its tone implies that this is the strongest evidence to date. But is it?

Back in 2009, the Environmental Protection Agency issued a rule, and a report to go with it, that greenhouse gases pose a public threat to health and welfare and, as such, should be regulated under the Clean Air Act. Armed with this hammer, both the Obama and Biden administrations set strict limitations on greenhouse gas emissions from cars, power plants, and industry. Since then, we have been saddled with electric vehicle mandates, the closing of coal-fired power plants, and the need to import vast quantities of rare earth minerals, solar panels, and wind turbine parts to facilitate a transition to so-called “renewable” wind and solar energy — which is neither clean nor green.

That report is now 16 years out of date. A new report was written for the EPA, but Administrator Lee Zeldin chose to ignore it. The Department of Energy elicited a report, written by five distinguished climatologists and economists — John Christy, Judith Curry, Steve Koonin, Ross McKitrick, and Roy Spencer. But that report was challenged by the Union of Concerned Scientists and the Environmental Defense Fund, who contend that the commissioning of the five scientists violated the Federal Advisory Committee Act. Subsequently, Secretary Chris Wright chose to disband the working group.

As usual, everything you read in the media is focused on partisan politics. The New York Times argues that the original 2009 report was correct and that its forecasts for a bleak future with rising temperatures and environmental disasters have indeed come true. The climate models are exonerated, the Times claims, and climate change is indeed much more of a danger now than it was back in 2009 when the EPA found greenhouse gases endangered the lives of everyone on the planet.

But I have read both the original 2009 report and the report issued by the Department of Energy. The Times pretends that the DoE report simply parrots the Trump administration’s party line. On the contrary, the DoE report is replete with citations from across the literature. This is the dirty little secret about climate change — you are told the science is settled and that the literature reflects one voice on climate change. The truth is, however, that many uncertainties and qualifications abound in the published, peer-reviewed literature. The so-called “consensus” simply does not exist. As Steven Schneider famously quipped in 1989,

We need to get some broadbased support, to capture the public’s imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have …. Each of us has to decide what the right balance is between being effective and being honest.

So, let me give you my take on that 16-year-old Endangerment Finding.

First, it must be noted that carbon dioxide is directly responsible for enhanced plant growth, increased agricultural productivity, and a global greening of the planet that NASA has estimated amounts to the equivalent of twice the leaf area of the continental United States. Moreover, enhanced carbon dioxide leads to a dramatic increase in the optimum growth temperature and causes the world’s plants to grow in a more water-efficient way.

Carbon dioxide is also a greenhouse gas that leads to a warming of the atmosphere, most notably the lower and middle troposphere. However, recent studies have shown that the effect of a doubling of carbon dioxide is on the order of 1 to 1.5°C of warming, not the 1.8 to 5.7°C suggested by most modeling studies. Climate models largely overstate historical and future warming due to (1) their over-sensitivity with respect to a rise in temperature resulting from an increase in carbon dioxide and (2) their use of overly unrealistic — indeed, exaggerated — carbon dioxide emission scenarios determining future carbon dioxide concentrations.

The key question that must be addressed is, “How will carbon dioxide cause changes in climatic processes that lead to the greatest loss of life and cause the most economic damage?” Long-term data do not exhibit significant changes in extreme weather events in the United States, which include droughts and floods, hurricanes, tornadoes, and wildfire activity. In addition, no indications exist that any of these events are likely to increase significantly because of increases in carbon dioxide. The rise in sea levels has continued since the demise of the last Ice Age, with past increases far exceeding the current rate. It is expected that sea level will continue to rise for the remainder of this century at the same rate it rose during the 20th century, as no significant acceleration has been observed.

Assessing small trends and patterns in climate variables is a difficult challenge. Climate varies for numerous reasons, including natural processes, solar activity, and chaotic turbulence. Our observational network is woefully biased, with more observations located in middle latitudes, lower altitudes, wetter climates, near the surface, and largely where people reside. Moreover, this network has changed over the years, with new instrumentation and platforms (for example, satellite and radar); stations being initiated, discontinued, and moved; and variations in observation times and procedures. Climate models suffer from a myriad of issues related to their inability to adequately describe an unknown and complex climate system that varies on spatial and temporal scales that the model simply cannot resolve.

This leads to the conclusion that warming arising from anthropogenic carbon dioxide increases is not likely to have the impact suggested by the EPA’s 2009 Endangerment Finding. Adaptation is preferable to expensive and potentially useless or, worse yet, detrimental mitigation, particularly because rising carbon dioxide concentrations are likely to have a potentially beneficial impact on the Earth’s climate.

David R. Legates, Ph.D. (Climatology), retired Professor of Climatology at the University of Delaware, is Director of Research and Education for the Cornwall Alliance for the Stewardship of Creation and co-editor of Climate and Energy: The Case for Realism (Regnery, 2024).