Rapid sea ice change events in regional Arctic scenario experiments

The Arctic summer sea ice extent is decreasing since the start of satellte observations 1979. On top of that, long-term trend variability exists, including record low extents followed by partial recovery. The latest example is the 2007 rapid ice loss event.

Rossby Centre's regional Arctic coupled ocean-ice-atmospher scenario experiments show a number of rapid sea ice loss events for projected warming Arctic climate. The nature and mechanism of those events are currently scrutinated. First results show that rapid ice loss during summer is favored by warm winter air temperatures over the Arctic ocean. Those are connected to anomalous air circulation patterns transporting warm air of pacific origin to the Arctic.

During summer, the events are supported by warm air flowing in from the Nordic Seas. Those conditions represent a average view on all rapid loss events. Individual events diverge and can be dominated by summer warming as well. The most extrem loss events are connected to stronger influence of the so-called “dipole anomaly”, a meridional surface air pressure anomaly pattern.

In the current version of the Arctic climate model, sea ice export plays only a minor role for explaining rapid loss events. The most strong recovery signals are connected to atmospheric circulation isolating the Arctic from mid-latitudes and thus preventing inflow of warm air.

During 2011, an updated version of the Arctic climate model will enable us to test the impact of higher resolution on the findings.

Temperature 2m, RC newsletter 2010
Figure 1. Average 2-m temperature difference between the winter before the ice loss summer and the mean of 10 winters before the event. Enlarge Image
Sea level pressure, RC newsletter 2010
Figure 2. Associated sea level pressure difference indicating inflow of warm air from the pacific area. Enlarge Image