Scenarios for Twenty-First Century US Precipitation Trends

Abstract:

Projections of 21^st century precipitation change differ substantially between models. These model differences in precipitation trends are not simply due to differing climate sensitivities. Rather, precipitation changes are in many cases driven by dynamical processes which are themselves poorly correlated with climate sensitivity, and thus must be considered separately.

We use a storylines approach applied to CMIP6 model data to assess various scenarios of future precipitation change in the United States. We find that the key features associated with differences in precipitation trends across models include (1) global average temperature, (2) tropical upper-troposphere temperature, (3) the El Niño-Southern Oscillation, (4) the Pacific-North American pattern, and (5) the North Atlantic Oscillation. We demonstrate how combinations of trends in these features can reinforce or cancel to produce high-impact or low-impact precipitation scenarios for various regions.