China's Contribution to Arctic Black Carbon Declined From 2009 to 2022

Abstract Black carbon (BC) aerosol is an important driver of Arctic warming, and China used to be a major contributor to the Arctic BC burden through long‐range atmospheric transport. Here we show that China's contribution declined significantly from 2009 to 2022, primarily due to reductions in domestic BC emissions following the implementation of clean air policies. Global chemistry‐transport model simulations indicate a relative decline of ∼3% yr −1 ( p < 0.05) in China's Arctic BC contribution, exceeding the decrease rate in the underlying emission inventory. Sensitivity simulations further suggest that climate change‐induced shifts in atmospheric transport may have amplified this decline. Observations of aerosol absorption coefficients ( σ ap ) at Arctic background observatories revealed steeper declines in σ ap when modeled China‐to‐total BC ratios were higher. Moreover, σ ap correlated positively with modeled BC from China, with stronger relationships as the modeled China‐to‐total BC ratios increased. Together, these results provide robust evidence that China's emission reductions have diminished its role in Arctic BC, contributing an estimated 0.02 W m −2 decrease in the direct radiative effect during the Arctic haze season.