Arctic Sea Ice Trends
UPDATE: As you can tell by the chart after the fold, the short-term fluctuation has evened out. The overall trend for the year leaves little room for setting a new record minimum, although the long-term trend at the North Pole will continue its decline.
Last year, a powerful combination of wind field patterns, warm water currents, and global warming effects came togethor to produce a record minimum extent of the Arctic ice cap. At the beginning of this melting season, scientists were torn on whether or not the trend would continue as it did last year; as late as late-June, some scientists gave as much as a 50% percent chance that we could see another record minimum year.
Of course, things didn’t quite play out as they did in 2007. While this year has seen significant melt (attributed to the formation of thinner, one-year ice), it hasn’t quite seen last year’s pattern. Skeptics around the blogosphere have rallied around this, and it has become one of the de-facto “smoking guns” disproving climate change. Even after scientists came out with a reasonable hypothesis as to why there hasn’t been another extreme melt off (unique densities in the ice due to enhanced snowfall as well as the lack of perfect melting conditions), skeptics continue to bring up the Arctic ice cap as some sort of last-quarter field goal win for their team.
However, was their victory premature?
The recent daily ice cap extent data published by the National Snow and Ice Data Center is showing that even though we’re past the period of maximum insolation at the North Pole, a somewhat faster-than-expected melt is occuring right now:
I’m not quite sure why this period of rapid melt is occuring. Furthermore, I am skeptical that it will lead to another record minimum extent of the ice sheet. However, the point must be made: science is a transient, ever-changing process. I wonder what the skeptics will say if the unlikely situation occurs that we see another record minimum extent? Unfortunately, if previous trends are any indication (in the blogosphere, not ice cap extent!), the “skeptical” attitude will shift from climate science to the legitimacy of the data and the so-called “motives” of the NSIDC.
Of course, this is still an extremely hypothetical situation. ScienceDaily reports:
Chances that the 2008 ice extent will fall below last year’s record minimum is about 8 percent, researchers forecast after having run a number of different models predicting the fate of the Arctic sea ice this summer. But there is still reason for concern; the scientists are almost certain the ice extent will fall below the minimum of 2005, which was the second lowest year on record. With a probability of 80% the minimum ice extent in 2008 will be in the range between 4.16 and 4.70 million km2.
Still, an estimated 8% chances suggests that the situation is very plausible, if not very likely. We’ll simply have to wait and see what the ice cap does. This applies to everyone monitoring the situation.