What is increasingly apparent, as researchers have warned for years, is that "polar amplification" is causing many of these changes to feed on themselves, amplifying each other year after year. In this regard, what is happening to Arctic sea ice is in many ways key.
As the National Snow and Ice Data Center (NSIDC) pointed out earlier this month, Arctic sea ice is not just diminishing in extent - the four lowest levels have been in the last four years - but it is also younger and thinner. That makes ice easier to melt each year, which in turn exposes greater areas of heat-trapping ocean, which causes further melting, making it more and more difficult for sea ice to recover to previous levels.
Among other impacts, such changes in sea ice cover could have significant and seemingly contradictory impacts on weather patterns in mid-latitudes. Rising heat from a warmer Arctic may increasingly disrupt the circumpolar winds that normally confine cold air within Arctic realms, allowing blasts of cold to hurtle south, similar to what happened when parts of the United States were buried under thick snow this past winter.