Emergent Predictability in the Northern Hemisphere Associated with Arctic Sea Ice Anomalies

Abstract:

Late summer and early fall arctic sea ice extent has declined dramatically, especially since 2007. We here identify atmospheric circulation and surface features across the northern hemisphere mid and high latitudes associated with this period since 2007 of rapid fall sea ice decline. At monthly to seasonal timescales, we report large anomalies in the zonal wind and geopotential height fields. At submonthly scales, we demonstrate how changes in the frequency of blocking events and associated prolonged temperature anomalies over populous mid-latitude regions have changed as well in conjunction with fall Arctic sea ice decline since 2007. This suggests that sea ice anomaly data can inform mid and high latitude climate prediction on interannual to decadal timescales.

We also analyze historical and RCP simulations from the latest CMIP5 models, and find that over 98 percent of all six year simulation intervals show a decline (or increase) of September ice extent trends that is smaller than what has been observed between 2007 and 2012. We close by briefly speaking to the question of whether the combination of 1) a new Arctic sea ice state in late summer/early fall and 2) mid-latitude teleconnections may be introducing new sources of predictability to mid-latitude weather and climate on interannual to decadal timescales.