Much of the reason for this thinness and smaller ice area was the consistent warmth throughout the autumn and winter. Across the Arctic Ocean, temperatures during this period were about 4.5 degrees Fahrenheit (2.5 degrees Celsius) above average, with parts of the Chukchi and Barents seas coming in at 9°F (5°C) above average. (The Chukchi Sea lies between Alaska and Russia, while the Barents Sea sits to the north of Scandinavia.)
The Arctic was one of the clear global hotspots that helped drive global temperatures to the second-hottest February on record and the third-hottest January, despite the demise of a global heat-boosting El Niño last summer.
That background warmth was amped up by repeated incursions of warm air brought by storm systems from the Atlantic. During one such episode in early February, temperatures above 80 degrees north latitude reached nearly 30°F (15°C) above normal winter temperatures of about -22°F (-30°C)
The record-low winter maximum doesn't necessarily herald a record low end-of-summer minimum come September, as summer weather patterns have a large effect on sea ice area. Sea ice was at record-low levels going into last summer, but fairly cool, cloudy conditions during the season held back the melt somewhat. A late-season surge in melt still pushed the summer minimum to the second lowest on record.
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In general, though, a low winter maximum means sea ice is already starting off the melt season on the wrong foot.
"Thin ice and beset by warm weather - not a good way to begin the melt season," NSIDC lead scientist Ted Scambos, said in a statement.
The rate of ice loss has been much steeper for the summer minimum than for winter maximum, with declines of 13.7 percent and 3.2 percent per decade, respectively.
But "while the Arctic maximum is not as important as the seasonal minimum, the long-term decline is a clear indicator of climate change," Walt Meier, a sea ice researcher at the NASA Goddard Space Flight Center, said in a statement.
The recent string of record-low winter maximums could be a sign that the large summer losses are starting to show up more in other seasons, with an increasingly delayed fall freeze-up that leaves less time for sea ice to accumulate in winter, Julienne Stroeve, an NSIDC scientist and University College London professor, previously said.