The role of reduced aerosol masking from air pollutant emission reductions in recent global warming acceleration (2013–2023)

Abstract

In recent years, the Earth has likely experienced an accelerated warming trend, raising growing interest in the possible contributing factors. From 2013 to 2023, global anthropogenic air pollutant emissions declined significantly and brought enormous public health benefits, but the contribution of reduced aerosol masking of greenhouse warming to recent trends remains uncertain. Using two state-of-the-art global climate models, we show that global air pollutant emission reductions during 2013–2023 caused a global effective radiative forcing of 0.16 W/m 2 (90% CI: 0.13 to 0.20), with international shipping, China, and other land regions contributing 0.05 W/m 2 (0.00 to 0.09), 0.07 W/m 2 (0.03 to 0.11), and 0.05 W/m 2 (0.00 to 0.09), respectively. International shipping contributes disproportionately to radiative forcing relative to its emission reductions, highlighting its high forcing efficiency. The combined forcings are estimated to have contributed a warming of 0.044 °C (0.012 to 0.076) over 2013–2023, accounting for 52% (14 to 90%) of the observed warming acceleration (0.084 °C/decade) relative to the 1970–2012 trend. Especially strong reductions in aerosol–cloud interactions are found over the North Pacific, driven primarily by the downwind impacts of East Asian emission reductions. Aerosol unmasking contributes to the recent acceleration of warming and highlights the importance of accurately quantifying air pollutant emission changes for future climate projections.