House Energy and Commerce

At Tuesday’s House Energy & Commerce Committee hearing on Climate Science and EPA’s Greenhouse Gas Regulation, Dr. Christopher Field of the Carnegie Institution for Science, presented a scary assessment of global warming’s impact on U.S. grain yields. Field’s written testimony states, in pertinent part:

In the United States, the observed temperature sensitivity of three major crops is even more striking. Based on a careful county-by county analysis of patterns of climate and yields of corn, soybeans, and cotton, Schlenker and Roberts (Schlenker and Roberts 2009) concluded that observed yields from all farms and farmers are relatively insensitive to temperature up to a threshold but fall rapidly as temperatures rise above the threshold. For farms in the United States, the temperature threshold is 84˚F for corn, 86˚F for soybeans, and 90˚F for cotton. For corn, a single day at 104˚F instead of 84˚F reduces observed yields by about 7%. These temperature sensitivities are based on observed responses, including data from all of the US counties that grow cotton and all of the Eastern counties that grow corn or soybeans. These are not simulated responses. They are observed in the aggregate yields of thousands of farms in thousands of locations. [click to continue…]