The decline in summer fallow in the northern Great Plains cooled near-surface climate but had minimal impacts on precipitation

Since the early 1980s, nearly 116,000 km2 of cropland that was once held in fallow during the summer is now planted in the northern North American Great Plains. To simulate the impacts of this substantial land cover change on regional climate processes, convection-permitting model experiments using the Weather Research and Forecasting model were performed to simulate modern and historical amounts of summer fallow.

The control simulation was extensively validated using multiple observational data products as well as eddy covariance tower observations. Results of these simulations show that the transition from summer fallow to modern land cover led to similar to 1.5 degrees C cooler temperatures and decreased vapor pressure deficit by similar to 0.15 kPa during the growing season across the study region, which is consistent with observed cooling trends.