Radiative Response to Large Decline in Anthropogenic Emissions From China Between 2008 and 2016 Is Modified by Simultaneous Biomass Burning Emission Changes

The recent large reduction in anthropogenic aerosol emissions across China has improved China's air quality but has potential consequences for climate forcing. This sharp reduction in anthropogenic emissions has occurred against a background influenced by changing regional biomass burning emissions over a similar period of time. Here, we use the UK Earth System Model (UKESM) to estimate aerosol instantaneous radiative forcing (IRF) due to changes in emissions of aerosols and precursors from biomass burning and anthropogenic sources (separately and in combination) over 2008–2016, with a focus on China and regions downwind. We also separately quantify the IRF due to changes in anthropogenic aerosol emissions inside China (CHN) and the Rest Of the World (ROW). Reductions in Chinese anthropogenic emissions of BC, SO2 and OC contributed −0.30 ± 0.01, +1.00 ± 0.04, and +0.05 ± 0.01 W m−2, respectively to IRF over China, accounting for ∼97% of the total local anthropogenic aerosol IRF. These emission changes contributed a remote regional IRF of 0.22 ± 0.04 W m−2 over the North Pacific Ocean. The reduction in SO2 emissions from China contributed a global IRF of equal magnitude to that from SO2 emissions from ROW (∼0.08 W m−2). Changes in global biomass burning emissions contributed 0.03 W m−2 (equivalent to over 20% of the magnitude of anthropogenic aerosol IRF), enhancing the global anthropogenic aerosol IRF, whereas they partly offset the anthropogenic IRF over China. Meanwhile, biomass burning emissions dominated the total IRF (around 98%) over the Arctic.