If one had to pick the region of the world most likely to influence the course of human history this century, the Middle East would be the obvious choice, due to its political volatility and rich oil resources. However, the Middle East may have a significant challenger next century from a seemingly unlikely place--Greenland. Why Greenland? Well, the Greenland ice sheet holds enough water to raise global sea level 7 meters (23 feet). There are worrisome signs that the ice sheet might be more vulnerable than we thought to significant melting near the end of the century, according to research results presented at last week's annual meeting of the American Geophysical Union (AGU) in San Francisco. The meeting is the world's largest annual gathering of climate change scientists.
For climate change scientists, Greenland is clearly the most important place in the world. You could tell this by the way glaciers with unpronounceable names like "Kangerdlugssuaq" rolled off their tongues in a smooth, practiced manner at talks given at the AGU meeting. At least 120 presentations focused on the Arctic or Greenland, and fully 52 of these concerned Greenland. I attended roughly 20 of these talks, and most of the presenters made it clear that they were quite concerned about the future of Arctic sea ice and the Greenland ice sheet, particularly in light of the astounding Arctic sea ice melt
that occurred in 2007. A number of these talks raised the possibility that we've reached a tipping point in the Arctic. A complete loss of summertime sea ice may occur between 2013 and 2040, three of the presenters said, with the resulting warming dooming the Greenland ice sheet to a slow but inevitable melting process over a period of centuries. None of the presenters expressed the view that the current melting of the Greenland ice sheet and Arctic sea ice was due to a natural cycle that would completely halt or reverse in the next few years or decades.
At a talk on "The Recent Arctic Warm Period", Dr. Jim Overland, an Arctic expert with NOAA's Pacific Marine Environmental Laboratory, didn't offer his view on whether a tipping point had been reached. Instead, he asked the audience to vote. The options he presented:
* A The melt back of Arctic sea ice observed in 2007 is permanent and will not lessen.
* B Ice coverage will partially recover but continue to decrease.
* C The ice would recover to 1980s levels but then continue to decline over the coming century.
Both Options A and B had audience support, but only one brave soul voted for the most conservative option C.Figure 1.
A research submarine breaks through the Arctic ice. Image credit: Bernard Coakley
.The latest news from Greenland
I was amazed see the tremendous breadth and intensity of research efforts focused on Greenland and the Arctic, presented at AGU. Extra funding has been given to research efforts as part of the International Polar Year (IPY) program
, scheduled to run March 2007 through 2009. Satellites like Icesat and GRACE measure the extent of Greenland's ice from above, aided by a fleet of small and large research aircraft. Scientists now have unmanned aircraft that can use runways or be launched by slingshot that can measure the extent of Greenland's melt water lakes. The air armada will be joined next year by the Total Pole Airship
, the first blimp used for Arctic studies. Manned and unmanned submarines measure the thickness of the sea ice surrounding the island, and both permanent and temporary bases dotted across Greenland and the polar sea ice house scientists doing land-based studies. Ships and buoys also add data from the ocean areas.
A short list of the results presented at AGU all point to an ice sheet in peril:
- Melting of snow above 2000 meters elevation on Greenland reached a new record in 2007 (Tedesco, 2007).
- Leigh Stearns of the University of Maine's Climate Change Institute showed that the contribution of Greenland melting to global sea level rise has doubled in the last five years. According to the 2007 IPCC report (see Figure 4.18),
Greenland may account for as much as 10% of the total global annual sea rise of about 3-4 mm/year (approximately 1.5 inches per decade).
- Sea Surface Temperatures (SSTs) have warmed over 5° C (9° F) over the waters west of Greenland since 1990 (Figure 1, to the right). This has caused the ice-free season to increase by over 60 days per year along the coast.
- The Greenland ice sheet has experienced conditions as warm as those today in the past. Lowell et al.
(2007) found organic remains in eastern Greenland that had just been exposed by melting ice, and dated these remains at between A.D. 800 to 1014. Thus, this portion of Greenland was ice-free about 1000 years ago, and temperatures were presumably similar to today's. Erik the Red took advantage of this warm period to establish the first Norse settlements in Greenland around 950 A.D. However, the climate cooled after 1200 A.D., and the Norse settlements disappeared by 1550.
For more information, see our new Greenland feature
on our expanding climate change page.
Lowell, T.V., et al.
, 2007, Organic Remains from the Istorvet Ice Cap, Liverpool Land, East Greenland: A Record of Late Holocene Climate Change,
, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract C13A-04.
Stearns, L.A., and G.S. Hamilton, 2007, New States of Behavior: Current Status of Outlet Glaciers in Southeast Greenland and the Potential for Similar Changes Elsewhere
, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract C13A-06.
Tedesco, M., "A New Record in 2007 for Melting in Greenland," EOS
, 88:39, 2007, 383.