22-27 April 2012, Montréal, Canada

From Knowledge to Action

Changing Arctic Sea Ice

Global ImpactsOne of the most visible signs of climate change in the Arctic is a significant loss in the aerial extent and thickness of sea ice. Along with other components of polar ecosystems, sea ice is part of the global climate system and plays a crucial role in its regulation. The loss of sea ice, its impacts and policy implications will be among the issues explored at the IPY 2012 Conference From Knowledge to Action, taking place in Montréal, Quebec, Canada in April 2012.

Sea Ice ExtentThe area covered by sea ice grows in the winter and shrinks in the warmer months, with the minimum extent usually occurring in September at the end of the summer melt.

"While there is natural variability in the sea ice minimum from year to year, there has been a substantial downward trend over the past 30 years. To date, the lowest aerial extent of sea ice on instrumental record occurred in September 2007 based on continuous satellite observations beginning in 1979," says Dr. David Barber, director of the Centre for Earth Observation Science at the University of Manitoba in Winnipeg, and leader of the Circumpolar Flaw Lead System Study, one of the world's largest International Polar Year (IPY) projects.

Sea ice reflects 80 percent of sunlight back into space, and with the Arctic losing about 72,000 square kilometres of it per year on average, it is increasingly being replaced by a dark ocean surface that absorbs 90 percent of sunlight. This increased energy entering the system has led to a warmer Arctic Ocean, more frequent extreme weather within the region and on the periphery, and less efficient circulation and cooling of the Atlantic and Pacific oceans, which ultimately affects global climate, says Dr. Barber.

Declining Sea Ice Thickness"There has also been a 40 percent decrease in the thickness of sea ice in the high Arctic over the past couple of decades. Multiyear ice (ice that has survived at least one melt season) now covers only 18 percent of the Arctic basin compared to 85 percent in the early 1980s," says Dr. Barber. In addition to Arctic warming, thinning ice is also caused by more frequent storms, which bring stored heat to the ocean surface. Storms also increase precipitation that may fall as snow on multiyear ice, insulating it and reducing its growth in thickness the following winter.

Estimates of when the Arctic Ocean may have its first ice-free summer are constantly being revised due to the accelerated pace of change underway. Earlier projections indicated that the Arctic may have an ice-free period by the year 2100, but Dr. Barber now estimates that this may occur around 2020 to 2030.

Policy Implications"New development in the Arctic needs to be carried out in a sustainable way and with the knowledge that there are still significant hazards despite declining sea ice," says Dr. Barber. "For example, there is now more first-year sea ice, which is thinner and can pile up into large ridges and rubble areas under severe storm conditions. This can pose just as big a hazard to certain types of development as multiyear ice."

The IPY 2012 conference will examine the key issues identified by IPY and other recent polar research and explore collaborative strategies and actions that address critical global issues including the sustainable development and environmental protection of polar regions.

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