For centuries, explorers dreamed of a Northwest Passage. Now, as the Arctic melts, that dream is becoming a reality. But is the world ready?
View Dan Rather Reports - A Crack in the Ice. Video hosted on Google. The Arctic is a large, cold area around the North Pole. The Arctic is not a clearly defined area. It includes the Arctic Ocean, many islands, and parts of the mainlands of North America, Asia, and Europe.
Scientists define the Arctic in three major ways. First, as the area north of the Arctic Circle (latitude 66°30′ north). Second, as the region north of the 10° C (50° F) summer isotherm. The summer isotherm is a line on a map drawn through locations with an average annual temperature of 0° C (32° F) or less and a mean temperature for the warmest summer month of 10° C (50° F). Third, the Arctic is defined as the region north of the tree line, the point beyond which trees do not grow. The summer isotherm and the tree line enclose roughly the same territory, which is somewhat larger than the region bounded by the Arctic Circle. The largest Arctic land areas are in Canada, Russia, Greenland (Kalaallit Nunaat), Scandinavia, Iceland, Alaska, and Svalbard and other islands.
Winter in the Arctic is long and cold, and summer is short and cool. The Arctic Circle marks the border of a zone in which the sun never rises during at least one day in winter and never sets during at least one day in summer. The number of days when the sun is or is not visible during the entire day increases toward the north. Latitude, which determines the length of daylight, influences climate, but nearby areas contrast sharply. For instance, on the Greenland ice cap average midwinter temperatures are -33° C (-27° F), whereas adjacent coastal settlements, whose climates are moderated by the relatively warm ocean, typically have a mean temperature of -7° C (19° F) in the same period. The North Pole is not the coldest spot in the Arctic, because its climate is moderated by the ocean. Oymyakon, in northeastern Siberia, holds the record low temperature of -68° C (-90° F). The coldest recorded temperature for North America is -65° C (-85° F), at Snag, in Yukon Territory. The characteristically low precipitation averages less than 250 mm (10 in) per year, the moisture being received in almost all locations. Despite their distance from industrialized areas, the polar regions are sometimes blanketed by a smoglike haze.
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 areas 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 freshwater to the oceans, potentially affecting ocean circulation such as the Gulf Stream, which is principally responsible for Europes moderate weather (see Ocean and Oceanography). 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.
The Arctic warming could have mixed results for mining, petroleum extraction, and other industries. On the one hand, the warming could open sea lanes year-round so that ships could transport more natural resources, and less sea ice could enable petroleum companies to increase offshore drilling for oil. On the other hand, the melting of the permafrost could damage roads, pipelines, and other facilities built to extract and transport natural resources.
Finally, the report warned of increased health problems, such as cancer and cataracts, for the Arctics human population, due to increased exposure to ultraviolet radiation from the Sun. Increased exposure is expected as a result of the depletion of the ozone layer in the stratosphere, the upper atmosphere, caused by global warming. Although global warming causes temperatures to rise in the troposphere, the lower atmosphere, it has the reverse effect on the stratosphere, causing lower temperatures and an increase in atmospheric ice crystals. Ozone molecules, which absorb harmful ultraviolet radiation, adhere to the surface of these ice crystals, creating an ozone hole that allows ultraviolet radiation to reach the surface of the Earth.
(From: HDnet.
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