Visualizing 2012’s Record Arctic Sea Ice Melt
The National Snow and Ice Data Center announced on September 19 that Arctic sea ice had reached its minimum extent for 2012 — and that minimum was drastically lower than the previous record, set in 2007, by an area about the size of Texas.
On average, more and more sea ice has been melting each summer, with widespread implications for the rest of the world. Studies show that most of the modern sea ice melt is most likely largely due to manmade global warming. When white, highly reflective ice melts to reveal darker seawater, the ocean absorbs heat from the sun, warming the water and air and making it more likely that there will be even more melting in later years. The extra heat can also lead, among other things, to the melting of surrounding permafrost, which threatens to release extra heat-trapping carbon dioxide and methane; the melting of land-based ice on Greenland, which adds to rising seas; and perhaps even to paradoxically colder winters in the U.S. and Europe.
The NSIDC’s graphic depicting the ice minimum, is based on satellite observations, shows the ice extent in white; the median ice extent from 1979-2000, which was far greater, as an orange outline; and the ocean in blue.
But there are other measures of how fragile the ice is. The graphic below shows how thick, multi-year ice is being replaced by thin, first-year ice that forms over open ocean — and which is all too easy to melt the following year. At the end of this melt season, most of the sea ice was of the thin, first-year variety.
One of the wild-card factors that may have helped to accelerate the ice loss this year (although experts are still debating this possibility), was the occurrence of an unusually intense storm that struck the Arctic Ocean in early August. It's possible that the winds from this storm helped break up the thin ice cover. This NASA visualization shows the likely effects of the storm on Arctic sea ice movement.
This image compares the 2012 low with a few key years starting back in 1979, when satellite measurements of sea ice extent began. The most impressive statistics: this year’s low features 51 percent less sea ice than the 1979 minimum, and 18 percent less ice compared to the 2007 record low.
And for an international perspective, the image below, showing the ebb and flow of annual sea ice in the four years with the lowest late-summer extent on record, and averages for the three most recent decades comes from the Japanese Aerospace Exploration Agency (JAXA).
Most dramatically, here’s an animation from NOAA that shows how Arctic sea ice shrank to a pale shadow of its winter glory from January to September, 2012