My apologies in advance for posting climate-related articles two days in a row, but recent data from both NASA and the National Snow and Ice Data Center (NSICD) are intriguing and pretty hard for me to ignore. Both releases show that the extent of Arctic ice has reached its lowest point in more than thirty years of measuring, an issue that bears watching.
NASA's analysis of ice coverage shows that on August 26th, 2012, the areal extent of Arctic ice reached a new generational low, breaking the previous record set back on September 18th, 2007. What is concerning about this is that melting is likely to continue for several weeks yet, suggesting that new records could still be set since the end of the melt season generally occurs between the middle and the end of September.
Here is a NASA image showing how this year's ice minimum is far smaller in area than the average minimum over the period from 1979 to 2010 as shown with the orange line:
The areal extent of Arctic ice on August 26th, 2012 was 1.58 million square miles, nearly 2 percent smaller than the previous record low of 1.61 million square miles reached in September 2007. Scientists have noted that, on average, over the last thirty years, each decade has seen a 13 percent decline in the minimum summertime extent of sea ice cover.
NSICD data shows that over the last six years, the six lowest ice extents in the satellite record have occurred. Here is a graph showing the average Arctic sea ice extent over the period from 1979 to 2000 (solid black line), the extent in 1980 in orange, the extent in 2007 (green dashed line) and the extent this year (solid blue line):
Normally at this time of year, sea ice is retreating at a rate of about 15,000 square miles per day. This year, the extent of sea ice declined very rapidly in early August and is now retreating at an average of about 29,000 square miles per day, nearly twice the average.
I realize that satellite coverage of Arctic ice conditions goes back only three decades, making it difficult to prove that current changes in ice extent are long term and irreversible. That said, many scientists believe that the polar regions act as the "canary in the coal mine" and that the impact of potential climate changing anthropogenic activities may be reflected first in the Arctic and Antarctic ecosystems.