Fig. 1, Right: Sea ice concentration Anomalies for September 2002, 2003, and 2004, along with the 1979-2000 median September ice edge (pink line), derived from passive microwave satellite imagery. These reveal that sea ice extent reached a record minimum in Sept. 2002, followed by two more low-ice years. While sea ice decline can result from natural variability associated with the dynamical Arctic Oscillation (AO), greenhouse warming also favors the AO phase most conducive to warming. Image courtesy of NSIDC, Boulder, CO (http://nsidc.org/)

Figure 2 (Above) Arctic surface air temperatures have increased in the past 50 years in Alaska and Siberia, with a cooling in Southern Greenland. (Click thumbnail for larger image with caption.)

Figure 3 (above) Additional declines of roughly 10-50% in annual average sea-ice extent are projected by 2100 in model simulations. Loss of sea ice is projected to be greater during summer than in the annual average. Top and left Figures provided by The Arctic Climate Impact Assessment (http://www.acia.uaf.edu). (Click thumbnail for larger image with caption.)