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The Arctic is being severely affected by global warming, according to a scientific study released in 2004. The four-year-long study, known as the Arctic Climate Impact Assessment, was produced by the Arctic Council, consisting of the eight countries that ring the Arctic Ocean along with scientists and members of indigenous groups living in the Arctic. The study found that the average temperature in the Arctic rose nearly 1°C (2°F), almost twice the rate as the rest of the world, in the past few decades. The average winter temperature rose nearly 2°C (4°F), while parts of Russia and Alaska saw average winter temperatures rise 8°C (11°F) since the 1970s.
The study attributed the rising temperatures to increased emissions of carbon dioxide and other greenhouse gases, mainly due to the burning of fossil fuels throughout the world. The study found that as a result of the warming there was widespread melting of glaciers and sea ice and a shortening of the snow season. The report found that the average annual extent of sea ice in the Arctic had decreased by nearly 1 million sq km (386,000 sq mi) since 1974, an area nearly equal to that of Texas and New Mexico. The melting was expected to worsen global warming by increasing the amount of dark area that absorbs sunlight and thus warms the planet.
The study warned that a number of problems could result from the increased warming. Glacial and snow melt and increased river runoff would add more fresh water to the oceans, potentially affecting ocean circulation such as the Gulf Stream, which is principally responsible for Europe’s moderate weather. Reductions in the amount of sea ice were also expected to shrink habitat for polar bears, seals, some seabirds, and other species, while climate change could also affect food sources, migratory routes, and breeding grounds for caribou and reindeer herds.
Studies published since the 2004 report have found evidence that Arctic Ocean sea ice is thinning and melting much faster than previous climate models predicted. By one estimate, the Arctic Ocean could be ice-free in summer by 2030, with reduced ice cover in winter. In the summer of 2007 the Northwest Passage from the Atlantic Ocean to the Pacific Ocean was open for the first time as a result of reduced sea ice. Unusually warm summer temperatures were also recorded on land in some areas. Continued warming could open sea lanes year-round so that ships could transport cargo and more natural resources. Less sea ice could also enable petroleum companies to increase offshore drilling for oil.
The thawing of permafrost may release large quantities of methane gas into the atmosphere. Methane is about 23 times stronger than carbon dioxide as a greenhouse gas. As the frozen ground in the Arctic melts, it forms ponds and lakes where methane-producing bacteria begin to feed on carbon from ancient organic material in the soil. Another effect of melting permafrost is damage to houses and roads, as well as to pipelines and other facilities built to extract and transport natural resources. Ground that was once stable can sink and crack as the frozen soil thaws.