Impacts of Irrigation on Surface Temperature and Precipitation Distributions in the United States

Abstract:

With over 55.8 million acres of irrigated farmland in the United States, we can expect substantial impacts on regional land-atmosphere coupling due to this expansive human land-use activity. In this study, we use a global climate model to examine both the local and remote impacts of US irrigation on surface air temperature and precipitation distributions, with a particular focus on the tails of these distributions. We use two model configurations to understand irrigation-induced changes within the context of natural climate variability. The first configuration has monthly climatological sea surface temperatures (SSTs), while, in the second, monthly SSTs vary from year-to-year. We analyze differences in temperature and precipitation for two irrigation ensembles (each with three 50-year simulations) relative to two control ensembles. We find significant shifts in seasonal temperature and precipitation distributions for major agricultural regions in California and the US Great Plains, with more limited effects downwind. Notably, these shifts include changes in extreme values, which underscore the importance of understanding the impacts of land-use activities on regional climate.