A pair of new studies shows that winter sea ice in the Arctic has shrunk dramatically in the past two years and that perennial ice in particular is disappearing.
Two types of sea ice cover the Arctic Ocean: thick perennial ice that resists thaw year-round and thinner seasonal ice that melts during the summer and freezes again in the winter. Both types are experiencing decline, according to analyses of microwave satellite data.
Researchers led by Joey Comiso of NASA's Goddard Space Flight Center in Greenbelt, Maryland found that the amount of ice covering the Arctic has declined by six percent over each of the last two winters.
"This amount of Arctic sea ice reduction the past two consecutive winters has not taken place before during the 27 years satellite data has been available," Comiso said.
The researchers said that warming temperatures and a shorter winter-ice season are likely to blame.
"In the past, sea-ice reduction in winter was significantly lower per decade compared to summer sea ice retreat," Comiso said. "What's remarkable is that we've witnessed sea ice reduction at 6 percent per year over just the last two winters, most likely a result of warming due to greenhouse gases."
And if this happens, we're going to see an ice free Arctic in the very near future.