The state of the Arctic ice in November 2009 is the worst of any November in recorded history. Arctic areal sea ice extent didn’t break the 2007 record for the absolute minimum, but it has never been this low in November. Further, the extent continues to be nowhere near the climatological average, just like it hasn’t been for most of this year. As I’ve stated before, that’s indicative that a new phase of the Arctic has been reached. For three years in a row, sea ice extent has bottomed out at well below two standard deviations from the average extent. For three years in a row, all-time ice-extent lows have been reached at some point in the season.
Here is my State of the Arctic post for Sep and for Aug. I didn’t post anything in late October because I had a feeling a record low extent would be set shortly, which it did. The big change since my last post is the presence of weather conditions that have kept ice from refreezing at the rate it normally does this time of year. Two years ago, adverse weather conditions developed during the summer. This year, they’re around in the fall. The effect is the same: relatively little ice compared to climatological norms. Here is a satellite representation of Arctic sea ice conditions from yesterday:
Compared to the minimum reached earlier this year, there has been a recovery in ice in the Canadian archipelago, along the northeast coast of Greenland and from the Arctic Sea toward Siberia.
For comparison purposes, here is the similar picture from August:
Here is the time series graph through yesterday:
Notice the rapid refreezing that occurred in 2007, but which didn’t happen so far this fall. No, this fall, a high-pressure system sat over the Beaufort Sea, while unusually low pressure dominated the Barents Sea, according to the NSIDC. This brought 6C (11F!) warmer than normal air temperatures up from Siberia, preventing robust ice growth in that area.
Sea ice extent averaged over October 2009 was 7.50 million sq. km., 1.79 million sq. km. below the 1979 to 2000 mean for October, and only 730,000 sq. km. above the record low for the month, which occurred in October 2007. I expect the average extent for November to be very close to 2007’s, perhaps a little higher, perhaps a little lower, but in poor shape compared to climatological conditions.
The NSIDC released a report at the beginning of November with an additional time series representation of conditions. It shows the last two years’ worth of time series data, plus 2005’s time series, with +/- 2 standard deviations from the climatological average on the same graph:
This graph was made before 2009’s time series line crossed over 2007’s (as in the graph above), but the point remains: ice extent conditions in the Arctic have entered a new state, a state much lower than the 1979-2000 average. The volume of ice has decreased year after year recently, leaving one- or two-year old ice the predominant type in the Arctic. This ice is less capable of withstanding the warmer temperatures that October’s weather patterns produced. New ice is less able to grow around the younger ice. While refreezing will occur every winter, the times when ice does or does not refreeze is more dependent on favorable weather regimes. Additionally, since the Arctic waters absorbed large amounts of solar radiation again this year, the water is warmer than it used to be this time of year. It has to release a lot of heat to the atmosphere before freezing can occur. Thus, the past few falls have seen ice growth in fits and starts, remaining well out of the 2 standard deviations of extent, which is becoming increasingly statistically significant.
The U.S. Senate is slowly drawing closer to considering climate and energy legislation. The 2009 Copenhagen climate summit starts in less than a month. So there are important policy decision points staring us in the face. What will we do about them? The Arctic has demonstrated quite clearly that it has shifted to a new state. The consequences of a warming planet are showing up all over, in places and in ways that were unforeseen even a few years ago. The rate of warming and of other climate change indicators are occurring much faster than recent predictions indicated, exposing our lack of understanding of the complex systems in play. Do we really want to keep trying to kick the can down the road and letting some other group to deal with things? Or do we recognize that it damage to ecosystems and societies is already occurring and now is the time to act to prevent catastrophic situations?
Cross-posted at SquareState.