Arctic sea ice (CLIM 010) - Assessment published Sep 2008

Justification for indicator selection

Reduction in Arctic sea ice has several feedbacks to the climate system. Snow-covered ice reflects 85 % of the sunlight (high albedo), whereas open water reflects only 7 % (low albedo). Less ice and snow will therefore accelerate both sea-ice decline and global warming. Reduced ice formation will also reduce the formation of dense deep water which contributes to driving ocean circulation. As the ice cover influences air temperature and the circulation of air masses, changes in weather patterns such as storm tracks and precipitation can be expected even at mid-latitudes (Serreze et al., 2007). Warming over the Arctic Ocean can also penetrate into the surrounding continents, raising concern about thawing of the permafrost with release of additional greenhouse gasses (Lawrence et al., 2008).
The sea ice is an ecosystem filled with life uniquely adapted to these conditions, from micro-organisms in channels and pores within the ice, rich algal communities underneath, to fish, seals, whales and polar bears. The diversity of life in the ice usually grows with the age of the ice floes. As the ice gets younger and smaller, the abundance of ice-associated species will be reduced, with a risk of extinction for some of them. Indigenous Arctic peoples adapted to fishing and hunting will face large economic, social and cultural changes.
Less summer ice will ease access to the Arctic Ocean's resources, though remaining ice will still pose a major challenge for operations most of the year. Expectations of large undiscovered oil and gas resources are already driving the focus of the petroleum industry and governments northwards. As marine species move northwards with warmer sea and less ice, so will the fishing fleet. It is however hard to tell whether the fisheries will become richer or not; fish species react differently to changes in marine climate, and it is hard to predict whether the timing of the annual plankton blooms will continue to match the growth of larvae and young fish. Shipping and tourism are likely to increase, although drift ice, short sailing seasons and lack of infrastructure will impede a rapid development of transcontinental shipping of goods; it is more likely that traffic linked to extraction of Arctic resources on the fringes of the Arctic sea routes will grow first. These activities offer new economic opportunities. At the same time they represent new pressures and risks to an ocean that has so far been closed to most economic activities by the ice. This should be met by better international regulations of these activities.
High interest in getting access to the resources in the Arctic may create tensions and security problems. However most borders in the Arctic Ocean have been drawn, thereby clearly defining who has the ownership to the resources and right to manage them. In the remaining unresolved issues of delimitation of the Exclusive Economic Zones and extended continental shelves, all the coastal states of the Arctic Ocean follow the procedures of the UN Convention of the Law of the Seas.

Scientific references:

• References ACIA, 2004. Impacts of a warming Arctic: Arctic Climate Impact assessment. Cambridge University Press, Cambridge, UK. Comiso, J. C.; Parkinson, C.; Gersten, R. and Stock, L., 2008. Accelerated decline in the Arctic sea ice cover. Geophysical Research Letters 35, L01703. Haas, C.; Hendricks, S. and M. Doble., 2006. Comparison of the sea ice thickness distribution in the Lincoln Sea and adjacent Arctic Ocean in 2004 and 2005. Annals of Glaciology 44: 247-252. Haas, C.; Pfaffling, A.; Hendricks, S.; Rabenstein, L.; Etienne, J.-L. and Rigor, I., 2008. Reduced ice thickness in Arctic Transpolar Drift favors rapid ice retreat, Geophysical Research Letters (in press). Holland, M.; Blitz, C. and Tremblay, B., 2006. Future abrupt reductions in the summer Arctic sea ice. Geophysical Research Letters 33. L23503, DOI:10.1029/2006GL028024. IPCC, 2007a. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Averyt, K. B.; Tignor M. and Miller H. L. (eds.), Cambridge University Press, Cambridge, UK. Lawrence, D. M.; Slater, A. G.; Romanovsky, V. E.  and Nicolsky, D. J., 2008. The sensitivity of a model projection of near-surface permafrost degradation to soil column depth and inclusion of soil organic matter, In press J. Geophys. Res. Meier, W. N.; Stroeve, J.; Fetterer, F.; 2007. Whither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record. Annals of Glaciology 46: 428-434. NSIDC (National Snow and Ice Data Center), 2007: Arctic Sea Ice Shatters All Previous Record Lows. http://www.nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html . Nesje, A.; Bakke, J.; Dahl, S. O.; Lie, O. and Matthews, J. A., 2008. Norwegian mountain glaciers in the past, present and future. Global and Planetary Change 60: 10-27. Nghiem, S. V.; Rigor, I. G.; Perovich, D. K; Clemente- Colon, P.; Weatherly, J. W. and Neumann, G., 2007. Rapid reduction of Arctic perennial sea ice. Geophysical Research Letters 34, L19504. Serreze, M.; Holland, M. and Stroeve J., 2007. Perspectives on the Arctic's Shrinking Sea-Ice Cover. Science 315: 1533-1536. Stroeve, J.; Holland, M.; Meier, W.; Scambos, T. and Serreze, M., 2007. Arctic sea ice decline: Faster than forecast. Geophysical Research Letters 34, L09501, DOI:10.1029/2007GL029703. UNEP, 2007. Global outlook for snow and ice. UNEP Arendal/ Nairobi 2007. Winton, M., 2006. Does the Arctic sea ice have a tipping point? Geophysical Research Letters 33.