The observed warming of the Arctic Ocean over the last 40 years has been largely attributed to human-driven changes in the Arctic due to greenhouse gases. Researchers from UC Santa Barbara and University of Washington, supported in part by CPO’s Climate Variability & Predictability (CVP) and Modeling, Analysis, Predictions, and Projections (MAPP) programs, are now taking a closer look at the role of internal variability in Arctic Ocean warming. Using both observational and modeling analyses, they investigated how a multiyear trend in the Arctic’s summertime large-scale atmospheric circulation has regulated upper ocean temperature since 1979. Their work, published in Nature Communications, offers physical understanding of the underlying mechanism of this atmosphere-ocean interaction and a quantification of its contribution to the recent warming compared with that due to human-led causes. Modeling simulations suggest that internal variability accounts for up to 25% of the warming since 1979 and up to 60% of warming from 2000 to 2018. These findings suggest that climate models need to include this internal process alongside anthropogenic drivers in order to realistically simulate Arctic Ocean temperature variability and trends.
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