Recent Arctic warming linkages to the amplification of Northeast Pacific Marine Heatwaves

Abstract:

Marine heatwaves are climatic extreme events that can devastate on marine ecosystems and socio-economic systems. Under global warming, the properties of marine heatwaves have been amplified, in particular, in the Northeast Pacific and these changes were detected in historical periods. It has been reported that the Northeast Pacific suffers from severe marine heatwaves, often called the Blob. Here we show that the Arctic sea ice forcing has the potential role in changes properties of marine heatwaves in Northeast Pacific based on the reanalysis datasets and idealized coupled model experiments. The distinct warming over the Arctic region has contributed to decadal trends in atmospheric circulation and low cloud fraction over North Pacific. This condition is favorable for increasing mean SST over Northeast Pacific through the modulation of surface heat fluxes. The mean SST warming is associated with the amplifying of marine heatwave properties along with the changes in the probability distribution shifted to warm-side. These results suggest that expected Arctic warming in coming decades may cause to amplify marine heatwaves over the Northeast Pacific.