Contrasting air pollution and surface temperature trends in South and East Asia: satellite observations and CMIP6 simulations assessment

Abstract. South and East Asia have experienced contrasting air pollution trends over recent decades, with implications for regional climate, particularly surface temperature. However, the consistency between recent satellite-observed changes and climate model projections remains under-documented. Using IASI, OMI, MODIS and CERES satellite observations, we examine how changes in gaseous pollutants (CO, NO₂, SO₂) and aerosol loading (AOD) are associated with surface temperature (T_skin) changes over South and East Asia during 2008–2025, considering other key variables affecting T_skin (cloud fraction, surface shortwave radiation (SSW_↓), vegetation cover). We compare observed changes with CMIP6 simulations under SSP1-2.6, SSP2-4.5, and SSP3-7.0 and discuss their evolution up to 2100. Observations reveal strong declines in CO, NO₂, SO₂, and AOD over East Asia and increases over South Asia. These trends align with a strong warming over East Asia and daytime cooling over South Asia, consistent with cloud fraction and SSW↓ trends. Vegetation greening reinforces cooling in South Asia while being outweighed by increased SSW↓ in East Asia. CMIP6 simulations reproduce observed gaseous pollutant changes over East Asia most consistently with SSP1-2.6, whereas South Asia lies between SSP1-2.6 and SSP2-4.5. AOD in both regions falls between SSP1-2.6 and SSP2-4.5. However, CMIP6 models do not reproduce the observed regional contrast in surface temperature. The extended historical period in CMIP7, overlapping with the satellite era, will provide new opportunities to evaluate model representations of recent air pollution changes and their associated climate responses.