September 2012 broke all records for Arctic sea ice, and not in a good way. The National Snow and Ice Data Center’s Sea Ice Index for September 2012 shows the lowest ever monthly averaged extent of sea ice, culminating in the lowest ever recorded sea ice extent on September 16. And it’s not the lowest by a just a little. The previous record, in September 2007, shocked climatologists by beating the previous record by 22%. And this year, September sea ice was 18% smaller even than that. Moreover, the Arctic sea ice minimum in 2007 was partly explained by a particularly warm summer, and winds that favored melting. But none of that was true in 2012, which makes this year’s record even more of a shock to climatologists.
According to the NSIDC, the 2012 Arctic sea ice record low is due to the dwindling of older, thicker sea ice in recent years, and a new prevalence for younger, thinner sea ice. This younger, thinner ice is more vulnerable to weather, such as a storm that tracked through the Arctic in early August. The storm quickly broke up the already decaying ice, making it more susceptible to melting.
For more information about the data, see the National Snow & Ice Data Center’s discussion. For more information and discussions of Arctic sea ice trends and their implications, check out the National Snow & Ice Data Center’s Arctic Sea Ice News & Analysis site.