Unraveling

The annual Arctic Report Card from NOAA paints a grim picture. 

Another ramification of the dramatic warming of the Arctic is that permafrost is now releasing more greenhouse gases, like methane, which is 100 times more potent of a greenhouse gas than CO2, during the winter. The report notes that this is happening now at a rate faster than that at which plants can absorb the gas during the summer, which means the Arctic has now become a net source of heat-trapping pollution.

Update (December 18):  More from Andrea Thompson.

Update (January 7, 2017):  An interview with Jennifer Francis from the Institute of Marine and Coastal Sciences at Rutgers University about arctic records. And Joe Romm discusses the global loss of sea ice.

Systems with amplifying feedbacks tend to have tipping points beyond which change is irreversible. In the case of the great polar ice sheets that will drive catastrophic sea level rise and ultimately inundate every major coastal city, we appear to be dangerously close to such tipping points.

Update (July 16, 2017):  "Arctic Heat Is Becoming More Common and Persistent".

Since 1979, the number of warm events has doubled and the number of days with mild air has tripled. There are now 21 days of mild weather at the North Pole in an average winter compared to just seven mild winter days at the start of record keeping.

Update (December 20, 2017):  This year's report card finds that "the region is now definitively trending toward an ice-free state".

Shortly after the beginning of the 21st Century, the Arctic began an environmental transition so extensive that it caught scientists, policymakers, and residents by surprise. The extent and duration of these transitions define the New Arctic, characterized by the lowest winter maximum in sea ice cover on record for 2017, the persistent and record warming of sea surface temperatures across the Arctic, and the downward trend in total ice mass of the Greenland ice sheet, just to name a few.

Update (December 12, 2018):  This year's report card finds that melting at both poles has been worse than previously thought. It notes that 95 percent of the Arctic's oldest ice has melted in the past 30 years.

Update (December 13, 2019):  This year's report card continues the bad news.

The Arctic could be releasing upwards of 600 million tons of net carbon per year, the report finds, potentially putting the region alongside Mexico, Canada, and South Korea as one of the world’s largest contributors to atmospheric CO2.