Study Destroys Basis of EPA Climate Regulations

Guest essay by Vijay Jayaraj

For two decades, the public has been bombarded with dire warnings of an impending climate-induced agricultural apocalypse. The claim is that a climate warmed excessively by the carbon dioxide emissions of human activity will ravage the food supply and plunge humanity into famine and chaos.

For many reasons, none of this ever made sense. Now, a new study published in Scientific Reports has turned this narrative of catastrophe on its head, revealing that a global temperature rise of even 5 degrees Celsius (9 degrees Fahrenheit) would not reduce crop yields—and might even increase harvests.

The paper, written by economist Ross McKitrick, dismantles a key pillar of the Biden Administration’s always-suspect upward revision of the “social cost of carbon”—a metric used by the U.S. Environmental Protection Agency to quantify the supposed economic damage of carbon dioxide emissions. The fivefold increase of the social cost of carbon—from $51 per ton of carbon dioxide to more than $250—was based partly on the assumption that warming would devastate agriculture.

The new findings aren’t just a minor correction to the scientific record; they are a reversal of dangerous conclusions drawn from sloppy—perhaps even fraudulent—analyses. Everything we’ve been told about climate change and food security is wrong.

How did the EPA arrive at a social cost of carbon that equates with mass starvation?

In 2014, a widely cited meta-analysis of crop-model studies claimed that a warming climate would slash global crop yields, an assertion that fed into subsequent models that influenced the Biden EPA’s social cost of carbon hike.

That original dataset, however, was flawed—crippled by missing variables. Of its 1,722 records, nearly half lacked critical data, such as changes in CO2 concentrations, leaving only 862 usable entries. This incomplete picture painted a grim outlook of crop yields declining with only modest warming.

McKitrick, undeterred by what had become climate orthodoxy, dug deeper. By revisiting the source material, he recovered 360 additional records, bringing the total to 1,222—about a 40% increase in usable data.

The additional information showed “positive average output gains for all crop types across the warming scenarios even up to 5 degrees Celsius”—a temperature jump far beyond warming predictions of the U.N.’s International Panel on Climate Change. This isn’t cherry-picking; it’s what happens when the full scope of evidence is examined.

“If over the next 100-200 years, yields of all crop types increase, it does not stand to reason that a global trade model could generate global welfare reductions,” writes McKitrick in his concluding remarks.

McKitrick’s findings, grounded in a more comprehensive dataset, suggest the doomsday assumption was built on sand. Far from heralding a collapse, the data show crop yields at least holding steady and even improving with significant warming.

Moreover, plants are not too frail for a warming world. They’re built to thrive in the contemporary temperatures of the 20th and 21st centuries.

Most crops fall into two categories: C3 and C4 plants, so named to reflect their different photosynthetic processes. C3 crops, such as wheat, rice, and soybeans, flourish in elevated CO2 conditions characteristic of the 21st century.

Carbon dioxide is food to plants, necessary for the process of photosynthesis—a process where oxygen is a byproduct.

Higher levels of CO2 act like a supercharger, boosting photosynthesis and water-use efficiency. Studies have long shown that CO2 enrichment in greenhouses can increase C3 yields by 20% to 40%. C4 crops—like corn and sorghum—are less responsive to CO2 but do well in hotter, drier conditions.

In summary, if crop yields don’t crash—if they hold steady or grow—the rationale for a sky-high social cost of carbon disappears.

The McKitrick study is consistent with an extensive historical record that documents human flourishing during earlier eras warmer than today. The Minoan Warm Period 3,000 years ago and the Roman Warm Period and Medieval Warm Periods that followed are examples.

Unfortunately, the United Nation’s International Panel on Climate Change—relied on by many as the standard-bearer for information on climate change—favors adherence to climate dogma over rigorous scientific inquiry. It often ignores cutting-edge findings like McKitrick’s.

So where do we go from here?

First, the social cost of carbon calculation needs a reset. A realistic assessment would show that carbon dioxide is a benefit, not a pollutant, and that increasing CO2 adds to global productivity rather than imposes costs on society.

The EPA must revisit its numbers, stripping out inflated agricultural damages and grounding its estimates in all the data available. It is time to look at the facts, trust the real science, and end the irrational governmental messaging that feeds climate hysteria.

This commentary was first published at The Daily Signal on March 16, 2025.

Vijay Jayaraj is a Science and Research Associate at the CO₂ Coalition, Arlington, Virginia. He holds an M.S. in environmental sciences from the University of East Anglia and a postgraduate degree in energy management from Robert Gordon University, both in the U.K., and a bachelor’s in engineering from Anna University, India.