Hydrologic Cycle in the Balance for Midwest US

A new study from Dartmouth College suggests that the fate of the climate during the summer growing season in the U.S. Midwest remains uncertain as a potential consequence of climate change. The study was published in the journal Water Resources Research with collaboration from scientists at Columbia University, National University of Singapore, and Massachusetts Institute of Technology. The results are particularly alarming for the agricultural industry which is a critical component to the U.S. Economy and global food security.

A new study from Dartmouth College suggests that the fate of the climate during the summer growing season in the U.S. Midwest remains uncertain as a potential consequence of climate change. The study was published in the journal Water Resources Research with collaboration from scientists at Columbia University, National University of Singapore, and Massachusetts Institute of Technology. The results are particularly alarming for the agricultural industry which is a critical component to the U.S. Economy and global food security.

Previous studies have investigated the effects of climate change on precipitation and air temperature, but few have focused on the effects on soil moisture, specifically in the Midwest. Soil moisture is a strong indicator of hydrologic cycle health; it reflects changes in precipitation, runoff, plant transpiration, and evaporation. This study combined model simulations with regional observations.

The team projected multiple iterations of summertime changes in the water cycle in the Midwest using models but got mixed results. Some experiments predicted wetter soil conditions while others predicted drier. The team believes the responses were highly influenced but the choice of global climate model selected. To counteract this, the researchers added data from an extensive observational dataset of the water budget in Illinois. With the additional information, no statistically significant change in soil moisture, air temperature, precipitation, streamflow, or groundwater levels over the past twenty-six years. This non trend contracts previous model predictions that projected increasing temperatures as have been seen in most parts of the world.

Jonathan Winter, lead author and assistant professor of geography at Dartmouth concludes that based on the analysis of model simulations and regional observations, “climate change impacts on the water cycle of the Midwestern United States remain uncertain.” Additionally, “Our findings also suggest that while increases in surface air temperatures have been insignificant so far, adaptation to projected increases in temperature should be given priority as the signal is robust and could have large impacts on crop yields.” Winter highlights the need for improved simulations of soil moisture by climate models and increased observations to better predict the effect of climate change on Midwest agriculture.

Sources: Dartmouth College