One can appreciate that sea ice is a barometer and important feedback for climate change when one considers the ice–albedo feedback in a comparative sense. Whereas the Greenland ice sheet is 3 kilometers thick, sea ice is 3 meters thick, underlain by an ocean deeper than the Greenland ice sheet is thick. During a season, the areal change of Arctic sea ice cover is roughly 4 times larger than the area of Greenland. These huge annual oscillations in the ice cover have occurred for longer than humanity has been able to ponder them. This is just one of the many aspects that capture our attention in considering the scientific problem of sea ice and climate, which is a principal area of interest for Ian Eisenman.