The University of Nebraska-Lincoln (UNL) has apparently released a study published in the journal Nature Plants with the following conclusions: "Soybean researchers: Climate change suppressing U.S. yields."
According to UNL's press release:
"U.S. farmers have increased soybean yields in the past 20 years by about 1/3 of a bushel per acre per year, Specht said. Those gains, of about 0.8 percent a year, resulted from adoption of higher-yielding soybean varieties and improved farming methods.
But the gains would have been 30 percent higher if it weren't for the higher temperatures and changing rainfall patterns resulting from climate change, the author-researchers concluded in their paper, which was published in Nature Plants. That works out to $11 billion in lost opportunity cost, they said.
'We're doing OK, but we could have done a heck of a lot better without climate change,' Specht said.
The United States experienced a warming trend during the May-September growing season during the study period of 1994 to 2003. Rainfall patterns have changed as well, increasing in spring and fall but declining in June, July and August."
Yes, the entire United States did experience "a warming trend during the May-September growing season during the study period of 1994 to 2003," but last I checked, soybeans were not grown over the entire country.
Instead, when we look at the NOAA National Climatic Data Center's information on May-September growing season temperatures in the soybean belt, there is absolutely no change.
No significant trends in the soybean belt average growing season temperatures since records began in 1895, or over the past century, or since 1970, or during the last three decades.
Next we have this statement from UNL: "Rainfall patterns have changed as well, increasing in spring and fall but declining in June, July and August." And here are precipitation amounts in the soybean belt for June through August since records began.
There are no significant declining trends in June through August precipitation for the soybean belt since 1895, 1915, 1970, or 1985. In fact, there are positive correlations towards more rainfall -- not less -- over each of these periods, and during the past 100 years, there is a highly statistically significant trend towards more precipitation from June to August.
Finally, here are soybean yields since records began in the USDA's National Agricultural Statistics Service database.
Last year (2014) set a record yield for soybeans -- by a long shot. At 47.8 bushels per acre, it beat the previous record of 43.5 bushels per acre set in 2010 by a full 10 percent. And over the last 20 years (i.e., 1995 to 2014), soybean yields are increasing at 0.44 bushels per acre per year, not 0.33, and the yield increases are accelerating over time.
It seems climate change concerns over soybean production in the United States have been overstated.