China aerosol reductions contribute to rapid ocean warming in the Northeast Pacific

What is it about?

The period 2010-2020 has seen the warmest Northeast Pacific sea surface temperatures ever recorded, with several prolonged extreme marine heatwaves. Although year-to-year internal climate variability may partially explain the occurrence of these events, why they have dramatically increased in frequency since 2010 remains elusive. We find that rapid aerosol depletion in China triggers atmospheric circulation anomalies beyond its source region, leading to substantial mean surface warming in the Northeast Pacific, which creates favorable conditions for extreme ocean warming events. Our results provide an important insight into the mechanisms of ocean-atmosphere changes in the North Pacific, and highlight the need to consider the exacerbated risks posed by reductions in anthropogenic aerosol emissions when assessing the impacts of climate change.

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Photo by Benjamin Elliott on Unsplash

Photo by Benjamin Elliott on Unsplash

Why is it important?

No one questions that the North Pacific is changing in the context of climate change, but previous studies have offered controversial explanations for the spate of heatwaves in the Northeast Pacific. Our results provide an important advance in understanding and attributing recent past climate change, which is relevant for assessing the likelihood of future heatwaves in the Northeast Pacific. In the coming decades, radiative heating from continued reductions in anthropogenic aerosol emissions will itself increase the frequency of such events, and the heating will also trigger large-scale atmospheric circulation anomalies with far-reaching impacts on climate and society well beyond the aerosol source regions. Our work also implies that reducing greenhouse gas emissions is the "cure" for mitigating long-term ocean warming and its associated disasters, while changes in anthropogenic aerosol emissions are one of the most important factors in accurately predicting and responding to them.