Observed (red line) and modeled September Arctic sea ice extent in millions of square kilometers. The solid black line gives the ensemble mean of the 13 IPCC AR4 models while the dashed black lines represent there range. From Stroeve et al. (2007) updated to include data for 2008. The 2009 minimum has recently been calculated at 5.10 million square kilometers, the third lowest year on record, and still well below the IPCC worst case scenario. Credit: Copenhagen Diagnosis, 2009
