Earth’s northern ice cap is heating up and melting down at an alarming, not previously predicted, rate. A paper just out in Wiley Interndisciplary Reviews: Climate Change, by Josefino Comiso and Dorothy Hall looks at recent historic transformations in the Arctic using satellite imagery, mainly from 1979 to the present. The decline of Arctic ice is so extreme that ice thought to have existed for over 1450 years is melting now. (None of the sea ice is really ancient, even the “old” ice recycles over geologically short time periods. But in the near future there will be virtually no “old” ice left in the region.)
According to author Josefino Cosimo, of NASA, “The Arctic region has been warming faster than anywhere else in the globe from 1981 to 2012. Such warming is manifested strongly in all components of the cryosphere in the Northern Hemisphere.”
The following list of chilling, or rather, not chilling, facts is paraphrased from the paper:
- Warming in the region has been amplified … with the rate of warming observed to be ~0.60±0.07 o
C per decade in the Arctic (>64 oN) compared to ~0.2 o C per decade globally during the last three decades.
- sea ice extent has been declining at the rate of ~3.8% per decade,
- while the perennial ice (represented by summer ice minimum) is declining at a much greater rate of ~11.5% per decade.
- Spring snow cover [is] declining by –2.12 % per decade for the period 1967 to 2012.
- The Greenland ice sheet has been losing mass at the rate of ~123 Gt per year (sea level
equivalence of 0.34 mm per year) during the period from 1993 to 2010
- for the period 2005 to 2010, a higher rate of [Greenland ice sheet] mass loss of ~228 Gt per year has been observed.
- the average area of mountain glaciers has declined by as much as 10% per decade during the period from 1960 to 2000.
- Increases in permafrost temperature have also been measured in many parts of the Northern
Hemisphere while a thickening of the active layer that overlies permafrost and a thinning of
seasonally-frozen ground has also been reported.
Here is the movie version of this review paper:
The review looks at clouds, albedo, and the Arctic Oscillation for insight as to how this is all happening. The Arctic Oscillation is one of those medium-term climate variations (like ENSO) which involves a large scale shift in the movement of air masses from one perennial pattern to another, often accompanied by effects having to do with sea surface temperatures or sea currents.
The Arctic Oscillation (AO), often referred to as Northern Annular Mode (NAM), has been regarded as among the most dominant modes in the [Northern Hemisphere], affecting atmospheric circulation and climate in the Arctic. Its direct impacts on the sea ice cover and wind circulation patterns have been evaluated using AO indices as presented for the entire year on a monthly basis in Figure 9a and for the winter period in Figure 9b. The plots show that the indices for both monthly and for the winter season are mainly positive since 1988 although there are years (e.g., 2010) when they become strongly negative. It has been previously reported that negative AO indices are associated with extensive ice cover while positive indices would correspond to a reduced sea ice cover. However, the indices have become nearly neutral in the recent decade while the sea ice cover continued to decline.
The authors conclude that the link between the Arctic Oscillation and recent changes in the Arctic is unclear. This is hard to interpret without further research but it may be bad news: The recent changes seen in the Arctic and possibly effects not covered in this paper (but discussed frequently on this blog) on global weather don’t seem to be associated with “natural variation.”
The graphic at the top of the post is figure one from the paper, and has this caption: Location Map of the Arctic Region including average sea ice extent (yellow line), sea ice cover during record minimum in summer of 2012 (shades of white), continuous and discontinuous permafrost (shades of pink), glacier locations (gold dots) and snow cover (average location of 50% snow line in black and maximum snow line in green as inferred from MODIS data).