Source: Arctic Monitoring and Assessment Programme (AMAP)
New report synthesizes scientific observations of Greenland Ice Sheet
December 14, 2009
Since 1999, CIRES Director Konrad Steffen, a lead author of the report, has been collecting and analyzing climate data on Greenland's ice sheet.
The Arctic Monitoring and Assessment Programme under the Arctic Council has issued a new report synthesizing the latest scientific findings on the Greenland Ice Sheet, "The Greenland Ice Sheet in a Changing Climate".
The report is a preliminary product under the Arctic Council project "Climate Change and the Cryosphere: Snow, Water, Ice and Permafrost in the Arctic" (SWIPA) and has been produced by some of the world’s leading experts. It synthesizes peer-reviewed scientific material available before the spring of 2009. It was presented by the Arctic Council Chair, Danish Minister of Foreign Affairs, Dr. Per Stig Møller, and Professor Dorthe Dahl- Jensen, at the UNFCCC COP15 side-event "Melting Snow and Ice, a Call for Action" on December 14, 2009.
Accelerated ice loss
One of the most alarming findings in the comprehensive assessment of the Greenland Ice Sheet is that the discharge of icebergs as a whole has increased by 30% over the past decade: from 330 billion tonnes (giga tonnes) in 1995 to 430 billion tonnes in 2005. "We know that the Arctic has warmed enormously over the past 50 years and that the temperatures over Greenland have increased by more than twice the global average. Despite these observations, it is deeply surprising and worrying to see the pace of the changes in the Greenland Ice Sheet", says convening lead author, Professor Dorthe Dahl- Jensen, University of Copenhagen.
Whereas only two decades ago the Greenland Ice Sheet seemed to be roughly in balance, recent measurements show that the balance has now shifted and that both surface melting and iceberg discharge have increased considerably. Estimates indicate that between 1995 and 2000 the Greenland Ice Sheet lost on average 50 billion tonnes of ice each year and, in 2003–2006, the loss increased dramatically to an average of 160 billion tonnes annually. To express the magnitude of this amount, it would be enough to provide every inhabitant on Earth with 64 litres of pure freshwater daily for one year.
"Our understanding of the Greenland Ice Sheet still has serious gaps limiting our ability to project the ice sheet’s sensitivity to climate change", says Dorthe Dahl-Jensen. "For instance, the dramatic acceleration of many fast-flowing glaciers and ice streams is still poorly understood and not fully implemented in the ice sheet models applied."
Growing contribution to sea level rise
Most current models suggest that ice loss from the Greenland Ice Sheet will contribute about 5–10 cm to the rise in global sea level by 2100, but higher estimates have also been made. If climate warming were to cause a widespread speeding-up of ice discharge from the outlet glaciers, as recent observations indicate may be occurring, then the contribution from the Greenland Ice Sheet to global sea level rise could be as high as 20 cm by 2100.
Some of the recent projections for global sea level rise by 2100 that include the contributions from the rest of the world’s ice masses and thermal expansion of the oceans, in addition to melt water from the Greenland Ice Sheet, are around 1 m.
While under most future climate scenarios, models suggest that it would take 3000 years or more for the Greenland Ice Sheet to melt completely, it is possible that ‘tipping points’ for destabilizing change could be reached within a much shorter time frame.
With this background, Professor Dorthe Dahl-Jensen underlines the importance of further research on the Greenland Ice Sheet, not least because the melting will have global consequences:
"Greenland’s Ice Sheet is the single largest body of freshwater ice in the northern hemisphere. It contains around 3 million km3 of ice and, if it were to melt completely, this would cause global sea level to rise by roughly 7 m. We know that IPCC predicts that by 2100, annual temperatures over the Arctic will be 3 to 8 °C higher than the average observed during the 1951–1980 period. But already now we are seeing how the areas experiencing surface melt are expanding northwards and that the periods of melt in southern Greenland are getting longer. The development in the last decade has taken scientists by surprise and it is still uncertain how the Ice will react to future climate change. Therefore, it is essential to intensify the ice sheet research", says Dorthe Dahl-Jensen.
Positive and negative effects of the melting Ice Sheet
The direct impacts of changes in the Greenland Ice Sheet on Greenland’s society are thought likely to be minor compared to the impacts of climate change generally, as concluded in the report. Based on historic observations and the strong drive for change in Greenland’s society today, it is likely that the consequences of changes in the Greenland Ice Sheet will be minor compared to socio-economic, cultural and demographic influences generated within the Greenlandic society and from international sources. Nonetheless, fisheries play the leading role in Greenland’s economy.
To date there has been almost no research on the effects of the melting Greenland Ice Sheet on marine ecology and much of the present knowledge on the effects of climate change is related to the melting and reduction of sea ice. Changes in drainage patterns around the Greenland Ice Sheet may, however, affect coastal waters and thereby cause changes in the distribution of marine fish stocks and game species.
The effects of climate change on non-renewable resources will mostly be through indirect effects on accessibility and transport.
"The retreat of ice is changing the possibilities for mining, sea transport and energy production in and around Greenland. This also means that Greenland will have a much more central location on the planet because transport between Europe, America and Asia could go across the Arctic Ocean", says Minik Rosing, lead author of the report’s chapter on socioeconomic and cultural aspects.
Furthermore, the report concludes that the people living from subsistence activities, especially in small and remote settlements, will be the ones most directly affected by climate change. Subsistence hunting for marine mammals and seabirds could be affected by changes in sea ice and sea temperature and increasing quantities of melt water from the Ice Sheet. Sea ice also affects traditional subsistence hunting and fishing in inshore areas, especially when the ice is too poor to support fishermen and dogs but too thick for small boats to break through.
Climate change presents Greenland with a range of new challenges. Minik Rosing sums up the dilemma in this way:
"Greenland has to find its delicate balance between, on the one hand, being able to exploit the mineral and natural riches and, on the other hand, not being exploited itself and not destroying Greenland’s nature and cultural identity."
Additional Resources:
Short (3 minute) and Full length (15 minute) videos presenting the GRIS-2009 results presented at the UNFCC COP XV, Copenhagen, December 2009, and the SWIPA Project.
Press kit (.zip file) containing:
- GRIS Press Release
- Three short press-ready, research-based stories on the Greenland Ice Sheet - Accelerating ice loss - Growing contribution to sea level rise - Pros and cons of melting ice
- Links to still photography
- Links to 3 time-lap movie clips of the Greenland Ice Sheet
- SWIPA Press Release
- Press contacts for GRIS and SWIPA
