Julienne reminded me of something I meant to write about today. In recent years, we have been seeing this pattern.
Arctic temperatures have been jumping up in September as the ice starts to freeze. The latent heat released when the water freezes, warms the air around it – transferring heat from the water to the air. Since there has been more open water in recent years, this has caused temperatures to go above average.
2010 seems to have broken the pattern, with much less warming this autumn – despite the rapid freeze. October temperatures (so far) have been the lowest since 2004.
Whatever caused the rapid decline in ice from 2005-2007 may have reversed.