A recent review article by Bader et al. (2011) examines the state of the science regarding the relationship between Arctic sea-ice, storminess and the North Atlantic Oscillation (NAO). It assesses the evidence drawn from observational and modeling studies drawing on about 250 peer-reviewed articles spanning nearly a half-century of scholarship through 2010 (several studies published subsequently are discussed in Sections III and IV). The main conclusions can be summarized as follows.

Arctic sea ice extent has significantly diminished in a manner inconsistent with internal variability alone and anthropogenic forcing has likely been a contributing factor. A poleward shift of mid-latitude storms has been observed during winter. There is low confidence on changes in either the number or intensity of mid-latitude storms, and also low confidence on the role played by sea ice forcing. A statistical relation between Arctic sea ice loss and occurrences of negative (blocked) phase of the North Atlantic Oscillation (NAO) have been observed in recent decades. Possible causal effects of the sea ice on the atmosphere are difficult to deduce from the observations because (i) to zero order the atmosphere forces sea ice, and (ii) there is strong internal variability of the NAO. Atmospheric model simulations designed to test climate sensitivity to specified Arctic sea ice change tend to reveal a wintertime blocked NAO response, but the seasonality and intensity of responses vary considerably among the different models used. Most coupled ocean–atmosphere models of the last IPCC AR4 project a significant future reduction in Arctic sea-ice with a moderate tendency to a positive (zonal) phase on the NAO. This shows that the forcing associated with the sea ice reduction is not the dominant forcing on the NAO in the future, though it does not negate the possibility that it may be a more influential factor (relative to GHG and aerosols forcing) in current climate.


Bader, J., M. Mesquita, K. Hodges, N. Keenlyside, s. Osterhus, and M. Miles, 2011: A review on Northern Hemisphere sea-ice, storminess and the North Atlantic Oscillation: Observations and projected changes. Atmospheric Research, 101, 809-834.