Sea ice is formed at the surface of the Arctic Ocean during winter. Most of it melts during the summer, but some can persist to become multi-year ice. The Arctic atmosphere has warmed by about twice the global average in the last 30 years, resulting in record reductions in Arctic sea ice extent and thickness, especially in summer.
Arctic sea-ice reductions have significant impacts locally, regionally and globally through effects on climate, wildlife and humans, and indirectly on sea level. The high albedo of ice means that much of the incoming solar radiation to the Arctic region is reflected back to space without being able to warm the atmosphere, land or sea. When the coverage of sea ice reduces, more radiation is absorbed, adding to warming and loss of sea ice. Sea ice also helps to regulate the exchange of heat, gases and moisture between the ocean and atmosphere, and impacts on ocean stratification, salinity, and the global atmospheric and ocean circulation.
The Arctic will continue to warm throughout the 21st century. Arctic seas could be free of sea ice in summer within a few decades.
PHOTO at top: iStockphoto.com/westphalia.
