Fast Climate Responses to Aerosol Emission Reductions During the COVID-19 Pandemic

The reduced human activities and associated decreases in aerosol emissions during the COVID-19 pandemic are expected to affect climate. Assuming emission changes during lockdown, back-to-work and post-lockdown stages of COVID-19, climate model simulations show a surface warming over continental regions of the Northern Hemisphere. In January-March, there was an anomalous warming of 0.05-0.15 K in eastern China, and the surface temperature increase was 0.04-0.07 K in Europe, eastern United States, and South Asia in March-May. The longer the emission reductions undergo, the warmer the climate would become. The emission reductions explain the observed temperature increases of 10-40% over eastern China relative to 2019. A southward shift of the ITCZ is also seen in the simulations. This study provides an insight into the impact of COVID-19 pandemic on global and regional climate and implications for immediate actions to mitigate fast global warming.