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Black carbon (BC) has previously been found to intensify haze in China by stabilizing the planetary boundary layer. With ocean, sea ice, and cloud feedbacks included in a global aerosol-climate model, we show that BC emitted from the North China Plain can be transported to the oceans, which in turn changes cloud structure and land-sea thermal contrast. As a result, East Asian winter monsoon wind speeds decrease over the North China Plain. This decrease causes air stagnation that can further intensify haze. Our results suggest that in addition to the local BC-induced interactions between aerosol and the planetary boundary layer, BC can also amplify haze in the North China Plain by weakening East Asian winter monsoon through ocean, sea ice, and cloud feedbacks. It implies that reducing BC emissions could have significant indirect benefits for air quality in the North China Plain.

Plain Language Summary China has been experiencing severe winter air pollution in recent years. The pollution particles harm human health, affect atmospheric visibility, and cause adverse effects on economic and societal activities. The poor air quality was linked to high emissions from human activities and air stagnation associated with meteorological conditions and climate change. Recent studies reported that black carbon (BC), one of the by-products when wood or coal is burned, could intensify pollution in China by stabilizing the lower atmosphere (i.e., weakening vertical air mixing and dispersion of pollution plumes). In this study, we show that in addition to the impact on atmospheric mixing, BC can also amplify particle pollution in the North China Plain by weakening the East Asian winter monsoon through ocean, sea ice, and cloud feedbacks. This implies that reducing BC emissions could help mitigate air pollution in the North China Plain.