Arctic, large, cold area of Earth around the North Pole. The Arctic includes the Arctic Ocean, many islands, and parts of the mainlands of North America, Asia, and Europe. The Arctic region is particularly sensitive to global warming and other climate change, and it has a major influence on climate and weather on the rest of the planet.
Scientists define the Arctic in a number of ways. Geographically, the Arctic is the area north of the Arctic Circle (latitude 66°30′ north) where 24 hours of daylight and 24 hours of night occur at least once a year. In terms of climate, the Arctic may be defined 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). In addition, the Arctic may be 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 Arctic is also defined as the region where permafrost remains continuously frozen throughout the year. Oceanographers sometimes define the Arctic as the portion of the northern oceans that is covered with ice for at least part of the year.
The largest Arctic land areas are in Canada, Russia (including Siberia), Greenland (Kalaallit Nunaat), Scandinavia (in parts of northern Norway, Sweden, and Finland), Iceland, Alaska, and Svalbard and other islands.
The name Arctic derives from Greek arktos “bear,” referring to the constellation of the Great Bear (Ursa Major), which circles the North Star in the night sky.
|II||THE NATURAL ENVIRONMENT|
Unlike Antarctica, an ice-covered continental plateau surrounded by oceans, the Arctic has a central ocean almost enclosed by land. One large gap exists between Greenland and Scandinavia, and much smaller breaks are among the Canadian Arctic Islands and at the Bering Strait, which separates Alaska and Siberia.
The principal geological elements of the Arctic include parts of three ancient landmasses, composed predominantly of granite and gneiss, which are called shields—the Baltic-Scandinavian-Russian Shield, the Angara Shield or Siberian Platform (in north central Siberia), and the Canadian Shield (including all the Canadian Arctic except for the Queen Elizabeth Islands). Several regions, such as most of Greenland, are permanently ice covered, and extensive coastal plains are along much of northern Siberia, parts of the northwestern mainland and islands of Canada, and the North Slope of Alaska. Mountain ranges are in the eastern Arctic region of Canada (notably on Baffin Island), in Yukon Territory, in northern Alaska, in coastal Greenland, in Iceland, and in northeastern Siberia.
|A||Ocean, Seas, and Coastlines|
The largest body of water in the Arctic is the Arctic Ocean, which connects with the North Pacific Ocean and North Atlantic Ocean. The Arctic Ocean includes the Barents Sea, the Beaufort Sea, the Greenland Sea, the Kara Sea, the Chukchi Sea, the East Siberian Sea, and the Laptev Sea, and connects to the Bering Sea and the North Sea. About 45,390 km (28,142 mi) of coastline border the Arctic Ocean.
Arctic sea ice has a major impact on global and local climate. Sea ice is sea water that freezes in winter and may partially melt in summer. As sea ice forms and ages, it slowly turns into fresh water as salt is expelled downward. Ocean water under sea ice has a higher concentration of salt and is denser than surrounding water. The denser salty water sinks, creating a giant circulation pattern that draws warm water near the surface toward the Arctic while colder, denser water flows toward the tropics at a deeper level. When sea ice melts, it creates a layer of less-dense fresh water at the surface of the ocean.
The white surface of the sea ice reflects sunlight and has a cooling effect, in contrast to dark open water that absorbs heat. Sea ice also blocks evaporation off the surface of the ocean—reduced sea ice can result in more intense Arctic storms from increased water vapor in the atmosphere. In addition, sea ice along coastal areas protects land areas from erosion by large waves caused by wind and storms.
Glaciers and ice sheets that reach the edge of the sea create icebergs, giant blocks of freshwater ice that break away and float in the ocean. The melting of icebergs and glaciers into the ocean can raise sea levels. Adding large amounts of less-dense fresh water can also change the flow of ocean currents and affect temperatures of water and air.
|B||Rivers and Lakes|
Low precipitation is characteristic of the Arctic, so large and elaborate river and lake systems are rare. In many places, however, permafrost (permanently frozen subsoil) restricts the downward drainage of meltwater from snow, and the water accumulates on the surface as shallow lakes, ponds, and marshes. In addition, rivers from more humid regions flow seaward across the dry Arctic terrain. Several large rivers are in the Russian Arctic, and the Mackenzie and Yukon rivers are in North America.
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.
Earth’s magnetic north pole affects the Arctic. The lines of force in Earth’s magnetic field converge around the pole, allowing charged particles trapped in Earth’s magnetosphere to strike the atmosphere over the Arctic. The particles cause auroras and can result in magnetic storms that affect communications worldwide.
|E||Vegetation and Wildlife|
The Arctic is not a frozen desert devoid of life on land or sea, even during the cold, dark winter months. Spring brings a phenomenal resurgence of plant and animal life. Low temperatures are not always the critical element—moisture, the type of soil, and available solar energy are also extremely important. Some animals adapt well to Arctic conditions; for instance, a number of species of mammals and birds carry additional insulation, such as fat, in cold months. Arctic summers with extended daylight attract breeding birds and other animals. Warming temperatures in recent decades have allowed some plants and animals that lived south of the Arctic to expand their ranges northward. However, pollution and climate change are also having negative impacts on Arctic wildlife.
The Arctic has more than 400 species of flowering plants. The vast stretches of treeless tundra that cover the plains and coastal regions consist of low creeping shrubs, grasses, thick growths of lichens and mosses, and herbs and sedges.
Abundant animal life inhabits the Arctic, both on land and in the sea. Arctic land mammals include polar bears, arctic foxes, ermines, martens, arctic wolves, wolverines, caribou, reindeer (domesticated caribou), musk ox, lemmings, and arctic hares. Marine mammals include seals, walruses, and many species of whales, including narwhals and belugas.
Birds are plentiful throughout the Arctic. The guillemot and little auk nest by the thousands along cliffs. Ravens, snow buntings, and sandpipers have been seen in the remotest northern land regions, as have the snowy owl and the gyrfalcon. Various species of gull, including the jaeger, also range far to the north. The Arctic tern spends the northern summer in the Arctic then flies to the Antarctic to spend the southern summer there. Among other characteristic Arctic birds are the eider duck, teal, loon, petrel, puffin, and ptarmigan.
Insects, found in the Arctic wherever vegetation exists, include bees, wasps, flies, butterflies, moths, beetles, and grasshoppers. Mosquitoes, black flies, and midges are common in tundra regions, and feed on the blood of warm-blooded animals.
Coastal waters are relatively rich in such fish as cod, flatfish, halibut, salmon, and trout. A large variety of invertebrates have been observed in Arctic seas.
Large deposits of several important minerals occur in the Arctic. Among them are petroleum, natural gas, iron ore, nickel, lead, zinc, coal, uranium, tin, diamonds, gold, and cryolite.
Although the Arctic seems remote from industrialized areas of the Northern Hemisphere, winds and ocean currents carry pollutants to the far north where they can become concentrated, contaminating the environment and entering the food chain. Other pollutants may be carried to the Arctic in the droppings of migrating birds. High levels of PCBs, dioxins, and mercury have been detected in the fat of marine mammals and in fish in the Arctic. These pollutants can pose a health danger to indigenous peoples in the region who eat seals and whales. Smoglike haze from distant industrial air pollution sometimes forms in the polar region.
Scientists have also found a major thinning of the ozone layer high in the atmosphere over the Arctic similar to the ozone hole found over the Antarctic. The ozone layer of the upper stratosphere is damaged by chemical reactions with chlorofluorocarbons and other chemicals. These reactions are enhanced by sunlight, winds, and cold temperatures. High-energy particles from the Sun during solar storms can also damage the ozone layer.
The earliest known evidence of humans in the Arctic comes from a site in Russia called Mamontovaya Kurya. In 2001 a team of archaeologists announced finding stone tools and a mammoth tusk with cut marks. The artifacts were dated to about 40,000 years ago during the ice ages. Scientists have not yet determined if the objects were made by modern humans or by Neandertals.
The first peoples to reach the Americas may have passed through the Arctic region on foot over a land bridge between Siberia and Alaska, or they may have followed a northern coastal route from Asia to North America using boats, arriving perhaps as early as 20,000 years ago. A few researchers have suggested that some groups of people could have come to the Americas from Europe by crossing the Atlantic Ocean along the edge of giant ice sheets that bridged the land and ocean between the continents during the ice ages.
Long before modern Europeans reached the Arctic, much of the region had a scattered population, with Iceland a notable exception. The indigenous peoples came from many ethnic groups, using various languages, but it is believed most migrated from Asia over a span of thousands of years. The Inuit eventually reached the Atlantic Ocean in eastern Greenland, and the Saami reached Norway.
About 20 national groups exist today in the Arctic areas of Russia. These include the Komi, or Zyrian, occupying Arctic areas of European Russia; the Yakut, living mainly in the Lena River Basin; the Tungus, inhabiting a large region east of the Yenisey River; the Yukaghir, dwelling chiefly between the Yana and Indigirka rivers; and the Chukchi, inhabiting extreme northeastern Siberia. The Arctic areas of North America contain three main ethnic groups—the Aleut, the Yuit, and the Inuit—who live in northern Canada and in Alaska. The Aleut mostly inhabit the region of the Bering Sea; the Native Americans generally occupy grasslands; and the Inuit live mainly in northern Alaska, northern Canada, and coastal areas of Greenland. Canada created the separate administrative region of Nunavut in 1999 to give the local Inuit population more control over their own government and cultural development.
All the indigenous residents of the Arctic originally depended entirely on hunting or fishing, or both, and employed natural materials for their clothing, tools, homes, and vehicles. Articles were well designed and skillfully made, and some were artistically decorated. Well-known are the Inuit kayak, parka, and harpoon. The indigenous peoples in the Arctic region today have adopted some modern technology such as guns and snowmobiles, but also retain rights to subsistence hunting of marine mammals and other traditional practices.
The Arctic has also been settled by persons from more southern areas. Norwegians and Russians reached the seacoast of northern Europe about 1,100 years ago, when the Norse were also settling Iceland. In recent times, scientists, miners, and missionaries have established communities in the Arctic.
There are no large cities in the Arctic areas of Alaska, Canada, and Greenland, the largest cities generally having fewer than 10,000 inhabitants. The Arctic regions of Scandinavia and Russia, however, contain several communities of considerable size, such as Murmansk and Noril’sk, in Russia, and Tromsø, in Norway. Reykjavík, Iceland, is an important urban center.
|IV||PATTERNS OF ECONOMIC DEVELOPMENT|
Economic activity in most of the Arctic is limited to obtaining and processing natural resources, especially fish and minerals.
The Arctic environment is generally unfavorable to the production of food by cultivation or animal husbandry. Reindeer herding, however, is important in northern Scandinavia and Russia and to a lesser extent in the Arctic areas of Alaska, Canada, and Greenland. Sheep are raised in southwestern Greenland and in Iceland. Dairy farming to supply nearby communities is widespread; almost 1 million cattle are in northern Russia alone.
Fish from rivers and lakes are important for the diet of people living in the Arctic. Russia has highly developed river fisheries serving the local population as well as customers in distant cities. The Arctic Ocean is among the world’s most important fishing grounds, and many countries send fishing boats to its waters. Large amounts of cod and shrimp are caught off western Greenland. Overfishing has become a problem in some regions, however.
The recovery of minerals is an important industry in several parts of the Arctic regions. In Russia, nickel, iron ore, and apatite are produced on the Kola Peninsula, and diamonds are mined in the Lena River valley. Other major mineral products in the Russian Arctic include gold, tin, coal, mica, and tungsten. Sweden has produced iron ore at Kiruna and elsewhere north of the Arctic Circle since about 1900, and Norway has an important iron-ore mine on its northern coast at Kirkenes. Lead, zinc, and molybdenum are produced in Greenland, which formerly recovered much cryolite at Ivigtut. Large coal mines are on Spitsbergen, one of the islands of Svalbard. Mineral products of the Canadian Arctic include uranium, copper, nickel, lead, zinc, asbestos, iron ore, diamonds, petroleum, and natural gas.
Major interest has focused on petroleum and natural gas deposits in the Arctic, particularly as milder temperatures and reduced ice resulting from global warming may make locating and extracting such resources easier in the future. Large-scale production of petroleum on the Arctic North Slope of Alaska began in 1977. A proposal in 1987 by the administration of Ronald Reagan to open up the Arctic National Wildlife Refuge to oil development met with strong opposition from various environmental organizations. Russia has made claims to areas of the seabed near the North Pole that may hold 10 billion barrels of petroleum. Norway has announced plans to drill for natural gas in the Barents Sea.
The North American Arctic is not of major manufacturing importance, except for raw-material processing. Costs of labor and transportation are too high for general manufacturing. Russia, however, has several important industrial areas in the north. These include the Kola Peninsula, the Pechora River valley, the Yenisey River valley, and the Lena River valley near Yakutsk. Raw materials are processed in the Canadian Arctic, and Greenland and Iceland have a variety of small-scale manufacturing industries.
Land and water transportation in the Arctic are hindered by year-round or seasonal obstruction by ice. Few roads serve the area, although some important arteries are in mainland Canada, northern Russia, and northern parts of Norway and Sweden. Coastal shipping is significant in several regions of the Arctic, notably in Russia, Scandinavia, Alaska, and Canada. Icebreakers clear shipping lanes in winter. Russia has a good river navigation system in summer. Air transportation is of great importance. Airports serve several communities, and “bush” airlines link isolated communities and mining operations with larger centers.
|V||CLIMATE CHANGE IN THE ARCTIC|
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 (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.
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.
|VI||EXPLORATION OF THE ARCTIC|
The Greeks of the 4th century bc were aware of the Arctic, parts of which had already been settled by Inuit and Native Americans. Early in the 9th century ad, Irish monks established a colony in Iceland. Vikings, or Norsemen, from Scandinavia reached there later in the century. About 982 the Norse explorer Erik the Red sighted and named Greenland. During the next four centuries, Norsemen probably visited the Canadian Arctic.
Subsequent Arctic exploration was largely motivated by the European need for sea routes to East Asia—the Northeast Passage along northern Asia and the Northwest Passage through the Arctic islands of North America. In 1553 the English navigator Sir Hugh Willoughby initiated the search for the Northeast Passage. His companion, Richard Chancellor, reached the site of modern Arkhangel’sk, on the White Sea, thus opening a new route to commerce.
The search for the Northwest Passage began in earnest when English explorer Sir Martin Frobisher reached the Canadian Arctic in 1576. In 1587 John Davis sailed through part of what became known as Davis Strait, between Greenland and Baffin Island. In 1610 Henry Hudson sighted the bay that was later named for him; it was explored from 1612 to 1613 by Sir Thomas Button from Wales. English navigator William Baffin explored what came to be called Baffin Bay in 1616.
Russian exploration of the coast of the Siberian Arctic was promoted by Tsar Peter the Great in the early 18th century. He employed Danish navigator Vitus Jonassen Bering, who in 1728 discovered the strait separating Siberia and Alaska that bears his name.
As part of a renewed effort to find the Northwest Passage, the British government in 1818 organized the first of several Arctic explorations under Sir William Edward Parry, who in 1819 reached Melville Island in the Canadian Arctic. In 1845 Sir John Franklin led a British expedition toward the Bering Strait from Lancaster Sound, an arm of Baffin Bay. After his two ships were trapped by ice in 1846, the crews abandoned the ships, and all 130 men (including Franklin) perished. Their disappearance led to many search parties, beginning in 1848. Adolf Erik Nordenskjöld of Sweden, aboard the Vega, from 1878 to 1879 became the first to complete the Northeast Passage.
The first official Arctic expedition from the United States, in 1881 and 1882, was part of the first International Polar Year. Under the command of Lieutenant Adolphus W. Greely, it was based at Lady Franklin Bay, on Ellesmere Island, and made observations on magnetic and meteorological phenomena. In 1884, when relief vessels finally arrived, 17 members of the expedition had perished from cold and starvation.
The Greenland ice cap was first crossed in 1888 by Norwegian explorer Fridtjof Nansen. In September 1893 Nansen attempted to cross the North Pole in the ship Fram, which entered the pack ice near the New Siberian Islands. The vessel attained latitude 86°14’ north, just short of the 90° mark of the North Pole, in August 1896.
Between 1886 and 1909 the American explorer Robert Edwin Peary headed several expeditions to the Arctic by way of Baffin Bay. He reached Cape Morris Jesup (on Greenland), the northernmost land point in the Arctic, in 1900. On April 21, 1906, during an attempt to reach the North Pole, he attained latitude 87°6’ north. On April 6, 1909, he finally reached the North Pole by dogsled over pack ice from Grant Land in northern Ellesmere Island. Some controversy continues to surround his claim to have reached the Pole. The first voyage by ship through the Northwest Passage was accomplished from 1903 to 1906 by the Norwegian explorer Roald Amundsen.
In 1906 Canadian-born American anthropologist Vilhjalmur Stefansson lived with the Inuit near the Mackenzie River delta. Between 1908 and 1912 Stefansson and Rudolph Anderson traveled in the Coronation Gulf-Victoria Island area, also to study the Inuit. From 1913 to 1918 Stefansson commanded the Canadian Arctic Expedition, during which new land was discovered in the Arctic Archipelago.
On May 9, 1926, American explorer Richard E. Byrd, along with the aviator Floyd Bennett, may have reached the North Pole by airplane, although this fact has been disputed. A few days later Amundsen, Lincoln Ellsworth, and Umberto Nobile completed a flight of more than 70 hours in the dirigible Norge, from Spitsbergen, Norway, across the North Pole to Alaska, about 5,460 km (about 3,390 mi); and in 1928 Australian explorer Sir George Wilkins and his pilot, Carl Benjamin Eielson, flew from Point Barrow, Alaska, to Spitsbergen.
The Union of Soviet Socialist Republics (USSR) established the Northern Sea Route Administration in 1932 to open commercial shipping through the Northeast Passage and to develop Siberian resources. In 1937 four Soviet scientists, led by I. D. Papanin, drifted for nine months on NP 1, a small ice floe, studying the ocean, and they subsequently set up temporary scientific stations on the drifting ice. By 1981 the USSR had established about 26 such stations and had also made many briefer landings on the Arctic Ocean ice for scientific purposes. During the summer of 1938, Soviet pilots V. P. Chkalov and M. M. Gromov made nonstop flights over the North Pole, to Vancouver, Washington, and to San Jacinto, California, in single-engine aircraft.
During World War II (1939-1945), several air bases and meteorological stations were established in Alaska, the Canadian Arctic, and Greenland, and in 1947 a scientific station was founded at Point Barrow, Alaska. In 1951 the U.S. Navy undertook Project Ski Jump in the Beaufort Sea, making many sea-ice landings. The first U.S. station on drifting ice was established early in 1952 by Joseph O. Fletcher.
Travel under the ice, long foreseen by Stefansson and Wilkins, became a reality in 1958, when the nuclear-powered USS Nautilus became the first submarine to traverse the Arctic Ocean. It went from the Bering Strait to Iceland via the North Pole in four days. Scientific activity in the Arctic increased greatly during the International Geophysical Year (IGY) from July 1957 to December 1958. The program involved several nations, which together operated more than 300 stations.
By the late 1970s, traditional exploration had been largely replaced by systematic data gathering and scientific research. Access had been greatly improved by airplane, submarine, icebreaker, and new overland transportation methods, and Earth satellites and automatic instruments had taken over much of the task of routine information collecting. The centennial of the Vega voyage of 1878 to 1879 was marked by a major research program by the Swedish icebreaker Ymer and an international scientific team working between the Barents Sea and northeastern Greenland. In the early 1980s, an international team of scientists pursued a long-term study of the Greenland ice cap by analyzing ice cores obtained by drilling from the surface to depths of about 2,040 m (about 6,690 ft).
Modern climate change has focused new attention on ancient climates in the Arctic region. In addition to ice cores from Greenland that date back thousands of years, scientists have looked for fossils of plants and animals that indicate what the climate was like in the Arctic millions of years ago. Because plate tectonics have shifted land masses over the eons, many of the oldest fossils in the Arctic represent animals that lived much further south before their remains were carried north. However, the northern continents were roughly in their modern positions by the Cretaceous Period, which lasted from about 145 to 65 million years ago. Scientists discovered fossils of dinosaurs in the North Slope region in Alaska in the 1980s and in the Arctic regions of Canada and Siberia in the 1990s. Dinosaurs that lived in the Arctic must have experienced periods without sunlight and relatively cold temperatures, although much milder than today and without ice caps.
Fossils of plants and animals that lived in the Arctic after the dinosaurs went extinct are also important sources of information. Of particular interest are fossils from the Eocene Epoch, which lasted from 56 to 34 million years ago. During the Eocene high levels of the greenhouse gas carbon dioxide made Earth much warmer than today. In 1986, on Axel Heiberg Island in the Canadian Arctic, the largest fossil forest yet found in the Arctic was dated at about 45 million years old, raising interesting questions about how plants adapted to changing environmental conditions there in the geological past. In 2004 the Arctic Coring Expedition (ACEX) retrieved a core of sediment from the Arctic seafloor that dated as far back as 40 million years, providing a long record of marine organisms from near the North Pole.
Major scientific research projects to study modern changes in the Arctic include the International Polar Year (IPY) 2007/2008, which runs from March 2007 to March 2009. The IPY involves thousands of scientists from more than 60 nations in more than 200 projects focused on the Arctic and the Antarctic. Topics of study include biology, geology, climatology, meteorology, oceanography, and geophysics. Also ongoing is the Arctic Ocean Diversity (ArcOD) Census of Marine Life. The ArcOD is part of the international Census of Marine Life (CoML), a ten-year international initiative begun in 2000 to study life in the oceans. Warming in the Arctic could cause major changes in sea life and threaten some species with extinction.