Similar spatial patterns of global climate response to aerosols from different regions

Abstract Anthropogenic aerosol forcing is spatially heterogeneous, mostly localised around industrialised regions like North America, Europe, East and South Asia. Emission reductions in each of these regions will force the climate in different locations, which could have diverse impacts on regional and global climate. Here, we show that removing sulphur dioxide (SO 2 ) emissions from any of these northern-hemisphere regions in a global composition-climate model results in significant warming across the hemisphere, regardless of the emission region. Although the temperature response to these regionally localised forcings varies considerably in magnitude depending on the emission region, it shows a preferred spatial pattern independent of the location of the forcing. Using empirical orthogonal function analysis, we show that the structure of the response is tied to existing modes of internal climate variability in the model. This has implications for assessing impacts of emission reduction policies, and our understanding of how climate responds to heterogeneous forcings.