The Direct Radiative Effect of CO₂ Increase on Summer Precipitation in North America

Precipitation changes in full response to CO 2 increase are widely studied but confidence in future projections remains low. Mechanistic understanding of the direct radiative effect of CO 2 on precipitation changes, independent from CO 2 ‐induced SST changes, is therefore necessary. Utilizing global atmospheric models, we identify robust summer precipitation decreases across North America in response to direct CO 2 forcing. We find that spatial distribution of CO 2 forcing at land surface is likely shaped by climatological distribution of water vapor and clouds. This, coupled with local feedback processes, changes in convection, and moisture supply resulting from CO 2 ‐induced circulation changes, could determine North American hydroclimate changes. In central North America, increasing CO 2 may decrease summertime precipitation by warming the surface and inducing dry advection into the region to reduce moisture supply. Meanwhile, for the southwest and the east, CO 2 ‐induced shift of subtropical highs generates wet advection, which might mitigate the drying effect from warming.