A significant fraction of land in the United States is used to meet our diverse needs for food, fiber, and, increasingly, biofuel. For example, over 40% of the corn production in the U.S. Midwest is now directed to produce bioethanol to support reductions in greenhouse gas emissions and boost energy security. Key weather and climate variables—temperature, precipitation, and radiation—are interrelated on a range of time and space scales. This covariability of factors is thus an important aspect in understanding the climate influence on bioenergy crop yields. The study, led by researchers at the Department of Energy’s Pacific Northwest National Laboratory, provides new  insights on the increasingly debated question of whether climate change leads to a net loss or gain for yields of two major bioenergy crops—corn and soybeans—in temperate regions like the United States.  By analyzing long-term (1983-2012) spatially distributed historical weather patterns and yields of the two major bioenergy crops, researchers found that studies that do not exclude the covariability among temperature, precipitation, and solar radiation can substantially overestimate the sensitivity of yields to a single climate factor, which highlights the importance of factoring in climate covariability when estimating climate change impacts on biomass production.  By including solar radiation, an additional 5% of variability can be explained for both crops. They found that regions using irrigation have been more resilient to historical climate change, suggesting that global warming may drive future increases in water use for bioenergy crop production.