I posted about this compilation here.
The animation is drawn from the Danish Meteorological Institute’s sea ice maps for August in each year from 1920 to 1939. The red marks show actual records of ice conditions and the white area is the inferred ice extent. The last image is the US National Snow and Ice Data Center’s satellite-derived sea ice concentration image for August 2012, for comparison.
For another view, there’s the historical sea ice extent compilation by Walsh and Chapman at the US National Center for Atmospheric Research / University of Illinois (as was plotted at Cryosphere Today):
[…] […]
Thanks. That’s a nice animation. Bookmarked.