It's that time again: The National Snow and Ice Data Center has weighed in on the now-annual saga of trying to forecast whether Arctic sea ice will melt down to a new record low. Sea-ice melt had been moving along at a pretty good clip earlier this year, though it's since proceeded at average levels, making it "highly unlikely" that a new record will be set.
At the end of the first half of August, NSIDC reports, sea ice extent was 2.3 million square miles, retreating at roughly 29,000 square miles per day, with many areas registering very low levels of ice concentration. This extent is well below the average for 1981 through 2010. Should melt continue apace, by mid September there should be roughly 2.0 million square miles of ice remaining.
In contrast to recent summers, and the region's above average warming trend, temperatures for the month of July were 4-7°F below average. The graphic below shows air temperatures and pressure for June to July 2012 (left) and the same period this year (right).
Last year Arctic sea ice reached its lowest extent since satellite records began in 1979, bottoming out at 1.32 square miles on September 16th—an area roughly the size of Texas and 49 percent below the 1979 to 2000 average.
The big question in all this—one that's important for not just climate, weather, and ocean circulation patterns, but also for transportation, geo-politics, resource usage, and inveitable nation-spating over each—is when will the Arctic be entirely ice-free.
A study recently published in the Proceeding of the National Academy of Sciences projects that the Arctic will most likely see it's first entirely ice-free summer sometimes between 2054 and 2058. That's smack in the middle ground between studies showing that we should've already seen an ice-free summer, and studies that say we won't see one until the end of the century. This projection is based upon high-emissions global warming scenarios, as in the path we're currently on. Should we reduce emissions we may be able to stave off total summer melt an additional ten years.
That said, this projection may be unduly conservative, if NOAA forecasts made in April of this year are anything to go on. According to this research, we'll see an ice-free Arctic summer definitely before 2050, and perhaps as soon as 2020.
So, which is it? Next decade? Or mid-century? A new record this year, next year, or sometime in the next five years? It's hard to say. Thought in either case, it's no longer a question of whether human-caused global warming will create an ice-free Arctic summer, but when.