Bering Strait Ocean Heat Transport Drives Decadal Arctic Variability in a High-Resolution Climate Model
The Bering Strait is a narrow and shallow passage that connects the North Pacific Ocean with the Arctic. Roughly 1 million m3 of water passes through the Bering Strait every second, carrying relatively warm waters into the Arctic Ocean. In this paper, we show that this heat transport has a stronger impact on Arctic surface temperatures and sea ice extent than the much larger ocean heat transport from the Atlantic side across the Greenland Scotland Ridge. Our analysis shows that the ice-albedo feedback strongly amplifies the atmospheric impact of Bering Strait heat transport.
Ocean heat transport into the Arctic Ocean is an important driver of the rapidly accelerating warming of the Arctic Earth system (Arctic Amplification). Most of the attention has been given to the Atlantic side, where warm Atlantic waters are known to enter the Arctic Ocean through the Barents Sea Opening and the Fram Strait. This paper highlights the importance of oceanic heat transport on the Pacific side as a major driver of Arctic warming, which has not previously been recognized.
We investigate the role of ocean heat transport (OHT) in driving the decadal variability of the Arctic climate by analyzing the pre-industrial control simulation of a high-resolution climate model. While the OHT variability at 65°N is greater in the Atlantic, we find that the decadal variability of Arctic-wide surface temperature and sea ice area is much better correlated with Bering Strait OHT than Atlantic OHT. In particular, decadal Bering Strait OHT variability causes significant changes in local sea ice cover and air-sea heat fluxes, which are amplified by shortwave feedbacks. These heat flux anomalies are regionally balanced by longwave radiation at the top of the atmosphere, without compensation by atmospheric heat transport (Bjerknes compensation). The sensitivity of the Arctic to changes in OHT may thus rely on an accurate representation of the heat transport through the Bering Strait, which is difficult to resolve in coarse-resolution ocean models.