Global warming is already limiting crop yields in some countries, according to two Stanford University researchers and a Columbia University researcher who completed a study they titled: “Climate Trends and Global Crop Production Since 1980.” The study was published in the journal Science last week.

In terms of the research abstract, the university professors provided their findings in scientific terms. “Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. Here, we show that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends for 1980–2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8 percent and 5.5 percent, respectively, compared to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, CO2 fertilization, and other factors.”

In other words, wheat and corn yields decreased over the years studied enough in major production countries to offset any gains in yield in other countries, and the researchers tied yield reductions in those countries to rising temperatures. The overall impact on production of rice and soybeans was negligible, with gains in some regions entirely offsetting losses in others.

Naming a few countries where they contend wheat yields are down are Russia, India, France and China and corn yields were off in China, Brazil and France.

The researchers suggested that extra carbon dioxide in the atmosphere has also “acted as a fertilizer that encouraged plant growth, offsetting some of the losses from rising temperatures caused by that same greenhouse gas,” a promotion of the Science journal noted.

The authors of the study—David Lobell and Justin Costa-Roberts of Stanford University, and Wolfram Schlenker of Columbia University—obviously went into the study convinced that global warming is occurring. They didn’t deny that climate change has been small so far, but they also contend that temperature increases will accelerate in coming decades, and they claim they have been conservative in their calculations by excluding short-term weather disasters such as floods.  

In what was probably not explained to any degree of satisfaction by those disagreeing with the concept of global warming was why the United States has not experienced the effects of global warming, especially in the main crop production areas of the country. Professor Lobell is quoted as saying the U.S. has been lucky to have been given a “pass on the first round of global warming.”

Most global warming advocates have talked about temperature changes in the last 25 plus years as being a couple degrees at most, but these data-collectors claim “temperatures increased briskly in many of the world’s important agricultural regions”—virtually all of Europe, large parts of Asia and some parts of Africa and South America have supposedly had several temperature degree increases since 1980.

“In many of these countries, a typical year now is like a very warm year back in 1980,” Lobell has been quoted as saying.

The author’s math might be questioned when they suggest that “foodstuffs” have doubled or tripled in price in recent years. Where exactly is not explained, but that isn’t in line with food prices in the U.S. It is the researchers’ contention that global food supply is extremely tight now and will become much tighter because of lower production caused by higher temperatures limiting production to feed an expanding world population. Besides limiting production, food is going to continue to rapidly accelerate in cost, the authors wrote.

“We aren’t talking about the sky falling,” Lobell said. “But we are talking about billions of dollars of losses. Every little bit of production is valuable when we’re trying to feed the world.”

It would appear that this study’s results would be even hard to swallow by less pessimistic global warming advocates.