The frozen cap of the Arctic Ocean appears to have reached its annual summertime minimum extent and broken a new record low of 1.32 million square miles on September 16, the National Snow and Ice Data Center (NSIDC) has reported.
Analysis of satellite data by NASA and the NASA-supported NSIDC at the University of Colorado in Boulder showed the new record minimum measures almost 300,000 square miles less than the previous lowest extent in the satellite record, set in mid-September 2007, of 1.61 million square miles, according to an article on NASA’s website. The article reports that the shrunken sea ice extent can be compared to the state of Texas, which measures around 268,600 square miles.
NSIDC cautioned that, although Sept. 16 seems to be the annual minimum, there’s still time for winds to change and compact the ice floes, potentially reducing the sea ice extent further. The article reports NASA and NSIDC will release a complete analysis of the 2012 melt season next month, once all data for September are available.
Arctic sea ice cover naturally grows during the dark Arctic winters and retreats when the sun re-appears in the spring, according to the article. But the sea-ice minimum summertime extent, which is normally reached in September, has been decreasing over the last three decades as Arctic ocean and air temperatures have increased. This year’s minimum extent is approximately half the size of the average extent from 1979 to 2000. This year’s minimum extent also marks the first time Arctic sea ice has dipped below 4 million square kilometers.
“Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions,” Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center, Greenbelt, Md., told NASA. “There continues to be considerable inter-annual variability in the sea ice cover, but the long-term retreat is quite apparent.”
The thickness of the ice cover is also in decline, according to NASA.
“The core of the ice cap is the perennial ice, which normally survived the summer because it was so thick”, Joey Comiso, senior scientist with NASA Goddard, told NASA. “But because it’s been thinning year after year, it has now become vulnerable to melt”.