Anthropogenic aerosols dominated the decreased solar radiation in eastern China over the last five decades

Abstract

Inter-decadal surface solar radiation (SSR) changes are closely related to climate change, such as global or regional warming, glacial melting, hydrological and carbon cycles, anthropogenic emissions of greenhouse gases and aerosols etc. Attributing the SSR trends is important for understanding these processes, however, the relative importance of anthropogenic effects and climate variability to the SSR long-term trend remains unclear. Previous attribution studies only considered the effects of aerosols or clouds, and mostly relied on correlation analysis method. Few focused on quantifying their relative contribution. In this study, we attributed the SSR trend during 1961–2014 in eastern China by using 11 Coupled Model Intercomparison Project phase 6 (CMIP6) models with the Bayesian model averaging (BMA) method. Results show that the BMA-based CMIP6 ensemble estimates well captured the decreasing trends of SSR in eastern China. Using CMIP6 factorial simulations, we quantified the relative contributions from three major drivers: anthropogenic aerosols forcing, GHG (greenhouse gases) forcing, and natural forcing. It shows that the anthropogenic aerosols dominated the SSR declining trends with relative contributions of 106.6 ± 34.6%, followed by GHG forcing (−3.0 ± 17.6%), natural forcing (−5.2 ± 14.9%) and their interactions (1.7 ± 26.2%). This study revealed that the observed long-term “dimming” over eastern China is mostly dominated by anthropogenic aerosols, implying the strong effects of air pollution on the SSR.