Zwischenablage des Galaxy S20 FE füllt sich mit Müll.

[Oi!Olli]

Edit, es war wohl ein Sync mit meinem S10, bei dem gerade der PC-Mark Akkutest läuft. Nur wie schalte ich den Sync aus?

Alter Text:

Kann es nicht besser beschreiben. Hab immer diesen Text in der Zwischenablage bei meinem S20 5G FE

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2. ARCTIC


The Arctic is a polar region located at the northernmost part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, the United States (Alaska), Denmark (Greenland), Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost. The area can be defined as north of the Arctic Circle (66° 33'N), the approximate limit of the midnight sun and the polar night. Alternatively, it can be defined as the region where the average temperature for the warmest month (July) is below 10 °C ; the northernmost tree line roughly follows the isotherm at the boundary of this region.

Socially and politically, the Arctic region includes the northern territories of the eight Arctic states, although by natural science definitions much of this territory is considered subarctic. The Arctic region is a unique area among Earth's ecosystems. The cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions. In recent years the extent of the sea ice has declined. Life in the Arctic includes organisms living in the ice, zooplankton and phytoplankton, fish and marine mammals, birds, land animals, plants and human societies.

2.1. ETYMOLOGY

The name refers either to the constellation Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere, or to the constellation Ursa Minor, the "Little Bear", which contains Polaris, the Pole Star, also known as the North Star.

2.2. CLIMATE

The Arctic's climate is characterized by cold winters and cool summers. Precipitation mostly comes in the form of snow. The Arctic's annual precipitation is low, with most of the area receiving less than 50 cm. High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can be as low as -40 °C, and the coldest recorded temperature is approximately -68 °C. Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. The Arctic is affected by current global warming, leading to Arctic sea ice shrinkage and Arctic methane release.

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Due to the poleward migration of the planet's isotherms (about 35 mi (56 km) per decade during the past 30 years as a consequence of global warming), the Arctic region (as defined by tree line and temperature) is currently shrinking. Perhaps the most spectacular result of Arctic shrinkage is sea ice loss. There is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2040 to some time well beyond 2100. About half of the analyzed models show near-complete to complete sea ice loss in September by the year 2100.

2.3. BIOTA

2.3.1. PLANTS

Arctic vegetation is composed of plants such as dwarf shrubs, graminoids, herbs, lichens and mosses, which all grow relatively close to the ground, forming tundra. As one moves northward, the amount of warmth available for plant growth decreases considerably. In the northernmost areas, plants are at their metabolic limits, and small differences in the total amount of summer warmth make large differences in the amount of energy available for maintenance, growth and reproduction. Colder summer temperatures cause the size, abundance, productivity and variety of plants to decrease. Trees cannot grow in the Arctic, but in its warmest parts, shrubs are common and can reach 2 m (6 ft 7 in) in height; sedges, mosses and lichens can form thick layers. In the coldest parts of the Arctic, much of the ground is bare; non-vascular plants such as lichens and mosses predominate, along with a few scattered grasses and forbs (like the arctic poppy).

2.3.2. ANIMALS

Herbivores on the tundra include the Arctic hare, lemming, muskox, and caribou. They are preyed on by the Snowy owl, Arctic fox and wolf. The polar bear is also a predator, though it prefers to hunt for marine life from the ice. There are also many birds and marine species endemic to the colder regions. Other land animals include wolverines, ermines, and Arctic ground squirrels. Marine mammals include seals, walrus, and several species of cetacean—baleen whales and also narwhals, killer whales and belugas.

2.4. NATURAL RESOURCES

The Arctic includes sizable natural resources (oil, gas, minerals, fresh water, fish and if the subarctic is included, forest) to which modern technology and the economic opening up of Russia have given significant new opportunities. The interest of the tourism industry is also on the increase.

The Arctic is one of the last and most extensive continuous wilderness areas in the world, and its significance in preserving biodiversity and genotypes is considerable. The increasing presence of humans fragments vital habitats. The Arctic is particularly susceptible to the abrasion of groundcover and to the disturbance of the rare reproduction places of the animals that are characteristic to the region. The Arctic also holds 1/5 of the Earth's water supply.

2.5. PALEO-HISTORY

During the Cretaceous, the Arctic still had seasonal snows, though only a light dusting and not enough to permanently hinder plant growth. Animals such as Chasmosaurus, Hypacrosaurus, Troodon, and Edmontosaurus may have all migrated north to take advantage of the summer growing season, and migrated south to warmer climes when the winter came. A similar situation may also have been found amongst dinosaurs that lived in Antarctic regions, such as Muttaburrasaurus of Australia.

2.6. INDIGENOUS POPULATION

The earliest inhabitants of North America's central and eastern Arctic are referred to as the Arctic small tool tradition (AST) and existed c. 2500 BC. AST consisted of several Paleo-Eskimo cultures, including the Independence cultures and Pre-Dorset culture. The Dorset culture (Inuktitut: Tuniit or Tunit) refers to the next inhabitants of central and eastern Arctic. The Dorset culture evolved because of technological and economic changes during the period of 1050–550 BC. With the exception of the Quebec/Labrador peninsula, the Dorset culture vanished around 1500 AD. Supported by genetic testing, evidence shows that Dorset culture, known as the Sadlermiut, survived in Aivilik, Southampton and Coats Islands, until the beginning of the 20th century.

Dorset/Thule culture transition dates around the 9th–10th centuries. Scientists theorize that there may have been cross-contact of the two cultures with sharing of technology, such as fashioning harpoon heads, or the Thule may have found Dorset remnants and adapted their ways with the predecessor culture. Others believe the Thule displaced the Dorset. By 1300, the Inuit, present-day Arctic inhabitants and descendants of Thule culture, had settled in west Greenland, and moved into east Greenland over the following century. Over time, the Inuit have migrated throughout the Arctic regions of Canada, Greenland, Russia and the United States.

Other Circumpolar North indigenous peoples include the Buryat, Chukchi, Evenks, Inupiat, Khanty, Koryaks, Nenets, Sami, Yukaghir, and Yupik, who still refer to themselves as Eskimo which means "snowshoe netters", not "raw meat eaters" as it is sometimes mistakenly translated.

2.7. INTERNATIONAL COOPERATION AND POLITICS

The eight Arctic nations (Canada, Denmark (Greenland & The Faroe Islands), Finland, Iceland, Norway, Sweden, Russia, and USA) are all members of the Arctic Council, as are organizations representing six indigenous populations. The Council operates on consensus basis, mostly dealing with environmental treaties and not addressing boundary or resource disputes.

Though Arctic policy priorities differ, every Arctic nation is concerned about sovereignty/defense, resource development, shipping routes, and environmental protection. Much work remains on regulatory agreements regarding shipping, tourism, and resource development in Arctic waters.

Research in the Arctic has long been a collaborative international effort, evidenced perhaps most notably by the International Polar Year. The International Arctic Science Committee, hundreds of scientists and specialists of the Arctic Council, and the Barents Euro-Arctic Council are more examples of collaborative international Arctic research.

2.7.1. TERRITORIAL CLAIMS

No country owns the geographic North Pole or the region of the Arctic Ocean surrounding it. The surrounding Arctic states that border the Arctic Ocean — Canada, Denmark (via Greenland), Iceland, Norway, Russia, and the United States —are limited to a 200 nautical miles (370 km; 230 mi) economic zone around their coasts.

Upon ratification of the United Nations Convention on the Law of the Sea, a country has ten years to make claims to an extended continental shelf beyond its 200 nautical mile zone. Due to this, Norway (which ratified the convention in 1996), Russia (ratified in 1997), Canada (ratified in 2003) and Denmark (ratified in 2004) launched projects to establish claims that certain sectors of the Arctic seabed should belong to their territories.

On August 2, 2007, two Russian bathyscaphes, MIR-1 and MIR-2, for the first time in history descended to the Arctic seabed beneath the North Pole and placed there a Russian flag made of rust-proof titanium alloy. The mission was a scientific expedition, but the flag-placing during Arktika 2007, raised concerns of a race for control of the Arctic's vast petroleum resources.

Foreign ministers and other officials representing Canada, Denmark, Norway, Russia, and the United States met in Ilulissat, Greenland on May 28, 2008 at the Arctic Ocean Conference and announced the Ilulissat Declaration, blocking any "new comprehensive international legal regime to govern the Arctic Ocean," and pledging "the orderly settlement of any possible overlapping claims."

As of 2012, Denmark is claiming the continental shelf between Greenland and the North Pole. The Russian Federation is claiming a large swath of seabed along the Lomonosov Ridge but confined to its sector of the Arctic.

2.7.2. EXPLORATION

Since 1937, the whole Arctic region has been extensively explored by Soviet and Russian manned drifting ice stations. Between 1937 and 1991, 88 international polar crews established and occupied scientific settlements on the drift ice and were carried thousands of kilometers by the ice flow.

2.7.3. POLLUTION

The Arctic is comparatively clean, although there are certain ecologically difficult localized pollution problems that present a serious threat to people's health living around these pollution sources. Due to the prevailing worldwide sea and air currents, the Arctic area is the fallout region for long-range transport pollutants, and in some places the concentrations exceed the levels of densely populated urban areas. An example of this is the phenomenon of Arctic haze, which is commonly blamed on long-range pollutants. Another example is with the bioaccumulation of PCB's (polychlorinated biphenyls) in Arctic wildlife and people.

2.7.4. PRESERVATION

There have been many proposals to preserve the Arctic over the years. Most recently a group of stars at the Rio Earth Summit, on June 21, 2012, proposed protecting the Arctic, similar to the Antarctic protection. The initial focus of the campaign will be a UN resolution creating a global sanctuary around the pole, and a ban on oil drilling and unsustainable fishing in the Arctic.

2.8. CLIMATE CHANGE

The Arctic is especially vulnerable to the effects of global warming, as has become apparent in the melting sea ice in recent years. Climate models predict much greater warming in the Arctic than the global average, resulting in significant international attention to the region. In particular, there are concerns that Arctic shrinkage, a consequence of melting glaciers and other ice in Greenland, could soon contribute to a substantial rise in sea levels worldwide. The climate models on which the IPCC report Nr.4 is based give a range of predictions of Arctic sea ice loss, showing near-complete to complete loss in September anywhere from 2040 to some time well beyond 2100. About half of the analyzed models show near-complete to complete sea ice loss in September by the year 2100. More recently, the Catlin Arctic Survey concluded that summer ice loss would occur around 2029. It has been apparent though since 2007, that those models grossly underestimate sea ice loss.

As can be seen in the two plot at the right, since about 1995 to 2000, all three size numbers of the Arctic sea ice shield (extent, area and volume) are decreasing in an accelerated way. This downward movement is modulated by statistical variations, which lead to considerable media attention, when a new record has been reached.

Concerning melting records, 2012 was a productive year, thus corroborating the tendency of the past decade. This may have been furthered by a strong summer storm cyclone, a rare event in the Arctic, which spread the already very thin ice and caused mixing of the cold surface waters with deeper warmer water layers. According to the University of Bremen, in September 2011 the Arctic ice cap was smaller than ever recorded (the satellite measurements started in the 1970s). Arctic ice is declining in area and thinning. Arctic temperatures have risen more than twice as fast as the global average over the past half century. The speed of change has shocked scientists. If current trends continue, a largely ice-free Arctic in the summer is likely within 30 years – up to 40 years earlier than was anticipated by the IPCC Fourth Assessment Report.

As the volume of sea ice until recently could not be measured by remote sensing as easy as its extent, numerical models have been made to estimate the ice thickness field between known points, which then is summed up to yield ice volume. The resulting volume over time reveals a much stronger loss of ice than ice extent studies suggest.

The current Arctic shrinkage is leading to fears of Arctic methane release. Release of methane stored in permafrost could cause abrupt and severe global warming, as methane is a potent greenhouse gas. On millennial time-scales, decomposition of methane hydrates in the Arctic seabed could also amplify global warming. Previous methane release events have been linked to the great dying, a mass extinction event at the boundary of the Permian and Triassic, and the Paleocene–Eocene Thermal Maximum, in which temperatures abruptly increased.

Apart from concerns regarding the detrimental effects of warming in the Arctic, some potential opportunities have gained attention. The melting of the ice is making the Northwest Passage, the shipping routes through the northernmost latitudes, more navigable, raising the possibility that the Arctic region will become a prime trade route. In addition, it is believed that the Arctic seabed may contain substantial oil fields which may become accessible if the ice covering them melts. These factors have led to recent international debates as to which nations can claim sovereignty or ownership over the waters of the Arctic.

The National Oceanic and Atmospheric Administration's Arctic Report Card presents annually updated, peer-reviewed information on recent observations of environmental conditions in the Arctic relative to historical records.



3. ARCTIC EXPLORATION

Arctic exploration is the physical exploration of the Arctic region of the Earth. It refers to the historical period during which mankind has explored the region north of the Arctic Circle. Historical records suggest that humankind have explored the northern extremes since 325 BC, when the ancient Greek sailor Pytheas reached a frozen sea while attempting to find a source of the metal tin. Dangerous oceans and poor weather conditions often fetter explorers attempting to reach polar regions and journeying through these perils by sight, boat, and foot has proven difficult.

3.1. FIRST ATTEMPTS

3.1.1. ANCIENT GREECE

Some scholars believe that the first attempts to penetrate the Arctic Circle can be traced to ancient Greece and the sailor Pytheas, a contemporary of Aristotle and Alexander the Great, who, in c. 325 BC, attempted to find the source of the tin that would sporadically reach the Greek colony of Massilia (now Marseille) on the Mediterranean coast. Sailing past the Pillars of Hercules, he reached Brittany and even Cornwall, eventually circumnavigating the British Isles. From the local population, he heard news of the mysterious land of Thule, even farther to the north. After six days of sailing, he reached land at the edge of a frozen sea (described by him as "curdled"), and described what is believed to be the aurora and the midnight sun. While some historians claim that this new land of Thule was the Norwegian coast or the Shetland Islands, based on his descriptions and the trade routes of early British sailors, it is possible that Pytheas reached as far as Iceland.

While no one knows exactly how far Pytheas sailed, he may have crossed the Arctic Circle. Nevertheless, his tales were regarded as fantasy by later Greek and Roman authorities, such as the geographer Strabo. It was impossible, according to their perception of the world, for man to survive in these 'uninhabitable reaches'.

3.1.2. THE MIDDLE AGES

Viking sailors reached the White Sea to the east and Greenland and North America to the west.
The first Viking to sight Iceland was Gardar Svavarsson, who went off course due to harsh conditions when sailing from Norway to the Faroe Islands. This quickly led to a wave of colonization. Not all the settlers were successful however in the attempts to reach the island. In the 10th century, Gunnbjörn Ulfsson got lost in a storm and ended up within sight of the Greenland coast. His report spurred Erik the Red, an outlawed chieftain, to establish a settlement there in 985. While they flourished initially, these settlements eventually foundered due to changing climatic conditions (see Little Ice Age). They are believed to have survived until around 1450.

Greenland's early settlers sailed westward, in search of better pasturage and hunting grounds. Modern scholars debate the precise location of the new lands of Vinland, Markland, and Helluland that they discovered.

The Scandinavian peoples also pushed farther north into their own peninsula by land and by sea. As early as 880, the Viking Ohthere of Hålogaland rounded the Scandinavian Peninsula and sailed to the Kola Peninsula and the White Sea. The Pechenga Monastery on the north of Kola Peninsula was founded by Russian monks in 1533; from their base at Kola, the Pomors explored the Barents Region, Spitsbergen, and Novaya Zemlya—all of which are in the Arctic Circle. They also explored north by boat, discovering the Northern Sea Route, as well as penetrating to the trans-Ural areas of northern Siberia. They then founded the settlement of Mangazeya east of the Yamal Peninsula in the early 16th century. In 1648 the Cossack Semyon Dezhnyov opened the now famous Bering Strait between America and Asia.

Russian settlers and traders on the coasts of the White Sea, the Pomors, had been exploring parts of the northeast passage as early as the 11th century. By the 17th century they established a continuous sea route from Arkhangelsk as far east as the mouth of Yenisey. This route, known as Mangazeya seaway, after its eastern terminus, the trade depot of Mangazeya, was an early precursor to the Northern Sea Route.

3.1.3. AGE OF DISCOVERY

Exploration above the Arctic Circle in the Renaissance was driven by the rediscovery of Classical learning and the national quests for commercial expansion. This exploration was hampered by limits in maritime technology of the age, lack of shelf-stable food supplies, and insufficient insulation for ships' crew against extreme cold.

3.1.4. RENAISSANCE ADVANCEMENTS IN CARTOGRAPHY

Patent from King Henry VII, authorizing John Cabot and his sons to explore new lands in the west.
A seminal event in Arctic exploration occurred in 1409, when Ptolemy's Geographia was translated into Latin, thereby introducing the concepts of latitude and longitude into Western Europe. Navigators were better able to chart their positions, and the European race to China, sparked by interest in the writings of Marco Polo, commenced. Just two years after Columbus in 1494, the Treaty of Tordesillas divided the Atlantic Ocean between Spain and Portugal. Forced to seek other routes to the Orient, rival countries like England, began considering the northern route over the top of the globe.

The Inventio Fortunata, a lost book said to be a description of travels in the North Atlantic by an unknown Friar, describes, in a summary written by Jacobus Cnoyen but only found in a letter from Gerardus Mercator, voyages as far as the North Pole. One widely disputed claim is that two brothers from Venice, Niccolo and Antonio Zeno, allegedly made a map of their journeys to that region, which were published by their descendants in 1558.

3.1.5. THE NORTHWEST PASSAGE

The Northwest Passage is a sea route connecting the Atlantic and Pacific Oceans through the Arctic Ocean. Since the discovery of the American continent was the product of the search for a route to Asia, exploration around the northern edge of North America continued for the Northwest Passage.

John Cabot's initial failure in 1497 to find a Northwest Passage across the Atlantic led the British to seek an alternative route to the east.

Interest re-kindled in 1564 after Jacques Cartier's discovery of the mouth of the Saint Lawrence River. Martin Frobisher had formed a resolution to undertake the challenge of forging a trade route from England westward to India. In 1576 - 1578, he took three trips to what is now the Canadian Arctic in order to find the passage. Frobisher Bay, which he discovered, is named after him. In July 1583, Sir Humphrey Gilbert, who had written a treatise on the discovery of the passage and was a backer of Frobisher's, claimed the territory of Newfoundland for the English crown. On August 8, 1585, under the employ of Elizabeth I the English explorer John Davis entered Cumberland Sound, Baffin Island. Davis rounded Greenland before dividing his four ships into separate expeditions to search for a passage westward. Though he was unable to pass through the icy Arctic waters, he reported to his sponsors that the passage they sought is "a matter nothing doubtfull ," and secured support for two additional expeditions, reaching as far as Hudson Bay. Though England's efforts were interrupted in 1587 because of Anglo-Spanish War, Davis's favorable reports on the region and its people would inspire explorers in the coming century.

3.1.6. THE NORTHEAST PASSAGE

The Northern Sea Route (capitalized) is a shipping lane from the Barent Sea to the Bering Strait along the Russian northern coast as currently officially defined by Russian Federation law; before the beginning of the 20th century it was known as the Northeast Passage.

The idea to explore this region was initially economic, and was first put forward by Russian diplomat Dmitry Gerasimov in 1525. The vast majority of the route lies in Arctic waters and parts are only free of ice for two months per year, making it a very perilous journey.

In the mid-16th century, John Cabot's son Sebastian helped organize just such an expedition, led by Sir Hugh Willoughby and Richard Chancellor. Willoughby's crew was shipwrecked off the Kola Peninsula, where they eventually died of scurvy. Chancellor and his crew made it to the mouth of the Dvina River, where they were met by a delegation from the Tsar, Ivan the Terrible. Brought back to Moscow, he launched the Muscovy Company, promoting trade between England and Russia. This diplomatic course allowed British Ambassadors such as Sir Francis Cherry the opportunity to consolidate geographic information developed by Russian merchants into maps for British exploration of the region. Some years later, Steven Borough, the master of Chancellor's ship, made it as far as the Kara Sea, when he was forced to turn back because of icy conditions.

Western parts of the passage were simultaneously being explored by Northern European countries like England, the Netherlands, Denmark and Norway, looking for an alternative seaway to China and India. Although these expeditions failed, new coasts and islands were discovered. Most notable is the 1596 expedition led by Dutch navigator Willem Barentsz who discovered Spitsbergen and Bear Island.

Fearing English and Dutch penetration into Siberia, Russia closed the Mangazeya seaway in 1619. Pomor activity in Northern Asia declined and the bulk of exploration in the 17th century was carried out by Siberian Cossacks, sailing from one river mouth to another in their Arctic-worthy kochs. In 1648 the most famous of these expeditions, led by Fedot Alekseev and Semyon Dezhnev, sailed east from the mouth of Kolyma to the Pacific and doubled the Chukchi Peninsula, thus proving that there was no land connection between Asia and North America. Eighty years after Dezhnev, in 1728, another Russian explorer, Danish-born Vitus Bering on Sviatoy Gavriil made a similar voyage in reverse, starting in Kamchatka and going north to the passage that now bears his name (Bering Strait). It was Bering who gave their current names to Diomede Islands, discovered and first described by Dezhnev.

It was not until in 1878 that Finnish-Swedish explorer Adolf Erik Nordenskiöld made the first complete passage of the North East Passage from west to east, in the Vega expedition. The ship's captain on this expedition was Lieutenant Louis Palander of the Swedish Royal Navy.

3.2. MODERN EXPLORATION

Roald Amundsen led the first expedition to reach the South Pole, was the first person to reach both poles, and was the first person to traverse the Northwest Passage.
In the first half of the 19th century, parts of the Northwest Passage were explored separately by a number of different expeditions, including those by John Ross, William Edward Parry, James Clark Ross; and overland expeditions led by John Franklin, George Back, Peter Warren Dease, Thomas Simpson, and John Rae. Sir Robert McClure was credited with the discovery of the Northwest Passage by sea in 1851 when he looked across M'Clure Strait from Banks Island and viewed Melville Island. However, the strait was blocked by young ice at this point in the season, and not navigable to ships. The only usable route, linking the entrances of Lancaster Sound and Dolphin and Union Strait was first used by John Rae in 1851. Rae used a pragmatic approach of traveling by land on foot and dog sled, and typically employed less than ten people in his exploration parties.

The Northwest Passage was not completely conquered by sea until 1906, when the Norwegian explorer Roald Amundsen, who had sailed just in time to escape creditors seeking to stop the expedition, completed a three-year voyage in the converted 47-ton herring boat Gjøa. At the end of this trip, he walked into the city of Eagle, Alaska, and sent a telegram announcing his success. His route was not commercially practical; in addition to the time taken, some of the waterways were extremely shallow.

3.2.1. THE NORTH POLE

On April 6, 1909, Robert Peary claimed to be the first person in recorded history to reach the North Pole (although whether he actually reached the Pole is doubted by some). He traveled with the aid of dogsleds and three separate support crews who turned back at successive intervals before reaching the Pole. Many modern explorers, including Olympic skiers using modern equipment, contend that Peary could not have reached the pole on foot in the time he claimed. In 2005 British explorer Tom Avery, with four colleagues, completed a trek to the pole in 36 days, 22 hours and 11 minutes using 16 husky dogs, and pulling two sledges which were replicas of those used by Peary. Some believe Avery's expedition has vindicated Peary, showing that Peary's speeds were not so impossible after all, since Avery's time was some four hours faster than Peary's claim. However a close examination of Avery's speeds only casts more doubt on Peary's claim: while Peary claimed to have made good an incredible 135 nautical miles (250 km; 155 mi) in his final five days, Avery managed only 71. Indeed, Avery never exceeded 90 nautical miles (170 km) made good in any five-day stretch. Further, Avery had the luxury of an airlift back to shore, and so had lightly loaded sledges in his final five days, while Peary was loaded down with all food and supplies needed for his return. Avery was able to equal Peary's 37-day total time only because Peary spent five days encamped by a big lead, making no progress at all.

A number of previous expeditions set out with the intention of reaching the North Pole but did not succeed; that of British naval officer William Edward Parry, in 1827, the American Polaris expedition in 1871, the ill-fated Jeannette Expedition in 1879 commanded by US Navy Lt Cmdr George W. DeLong, and Norwegian Fridtjof Nansen in 1895. American Frederick Cook claimed to have reached the North Pole in 1908, but this has not been widely accepted.

The crew of the airship Norge (including Roald Amundsen and the American sponsor Lincoln Ellsworth) observed the Pole on May 12, 1926. This is the first undisputed sighting of the Pole. Norge was designed and piloted by the Italian Umberto Nobile, who overflew the Pole a second time on May 24, 1928.

The first people to have without doubt walked on the North Pole were the Soviet party of 1948 under the command of Alexander Kuznetsov, who landed their aircraft nearby and walked to the pole.

On August 3, 1958, the US submarine Nautilus reached the North Pole without surfacing. It then proceeded to travel under the entire Polar ice cap. On March 17, 1959 the USS Skate surfaced on the North Pole and dispersed the ashes of explorer Sir Hubert Wilkins. These journeys were part of military explorations stimulated by the Cold War context.

On April 19, 1968, Ralph Plaisted reached the North Pole via snowmobile, the first surface traveler known with certainty to have done so. His position was verified independently by a US Air Force meteorological overflight. In 1969 Wally Herbert, on foot and by dog sled, became the first man to reach the North Pole on muscle power alone, on the 60th anniversary of Robert Peary's famous but disputed expedition.

The first persons to reach the North Pole on foot (or skis) and return with no outside help, no dogs, air planes, or re-supplies were Richard Weber (Canada) and Misha Malakhov (Russia) in 1995. No one has completed this journey since.

U.S. Air Force Lieutenant Colonel Joseph O. Fletcher and Lieutenant William Pershing Benedict landed a plane at the Pole on May 3, 1952, accompanied by the scientist Albert P. Crary.

On 2 May 2007, BBC's Top Gear got to the 1996 position of the pole (0.7 miles SSE) in modified Toyota Hilux.

On 2 August 2007 Arktika 2007 went to the sea-bed below the pole.

On April 26, 2009, Vassily Elagin, Afanassi Makovnev, Vladimir Obikhod, Sergey Larin, Alexey Ushakov, Alexey Shkrabkin and Nikolay Nikulshin after 38 days and over 2,000 km (1,200 mi) (starting from Sredniy Island, Severnaya Zemlya) drove two Russian built cars "Yemelya-1" and "Yemelya-2" to the North Pole.



4. DRIFTING ICE STATION

Soviet and Russian manned drifting ice stations are important contributors to exploration of the Arctic. The stations are named North Pole followed by an ordinal number: "North Pole-1,"... etc.

4.1. OVERVIEW

"NP" stations carry out the program of complex year-round research in the fields of oceanology, ice studies, meteorology, aerology, geophysics, hydrochemistry, hydrophysics, and marine biology. On average, an "NP" station is the host for 600 to 650 ocean depth measurements, 3500 to 3900 complex meteorology measurements, 1200 to 1300 temperature measurements and sea water probes for chemical analysis, 600 to 650 research balloon launches. Magnetic, ionosphere, ice and other observations are also carried out there. Regular measurements of the ice flow coordinates provide the data on the direction and speed of its drift.

The modern "NP" drifting ice station resembles a small settlement with housing for polar explorers and special buildings for the scientific equipment. Usually an "NP" station begins operations in April and continues for two or three years until the ice floe reaches the Greenland Sea. Polar explorers are substituted yearly. Since 1937 some 800 people were drifting at "NP" stations.

There are two groups of "NP" stations:

* stations, drifting on the pack ice (i.e. relatively thin and short-lived ice):"NP-1" through "NP-5", "NP-7" through "NP-17", "NP-20", "NP-21"
* stations, drifting on ice islands (glacier fragments, that were split from the shore): "NP-6", "NP-18", "NP-19", "NP-22".

All "NP" stations are organized by the Russian (former Soviet) Arctic and Antarctic Research Institute (AARI).

4.2. HISTORY

An idea to use the drift ice for the exploration of nature in the high latitudes of the Arctic Ocean belongs to Fridtjof Nansen, who fulfilled it on Fram between 1893 and 1896. The first stations to use drift ice as means of scientific exploration of the Arctic originated in the Soviet Union in 1937, when the first such station in the world, North Pole-1, started operations.

North Pole-1 was established on May 21, 1937 some 20 km from the North Pole by the expedition into the high latitudes Sever-1, led by Otto Schmidt. "NP-1" operated for 9 months, during which the ice floe travelled 2,850 kilometres. On February 19, 1938, Soviet ice breakers Taimyr and Murman took off four polar explorers from the station, who immediately became famous in the USSR and were awarded titles Hero of the Soviet Union: hydrobiologist Pyotr Shirshov, geophysicist Yevgeny Fyodorov, radioman Ernst Krenkel and their leader Ivan Papanin.

Since 1954 Soviet "NP" stations worked continuously, with one to three such stations operating simultaneously each year. The total distance drifted between 1937 and 1973 was over 80,000 kilometres. North Pole-22 is particularly notable for its record drift, lasting nine years. On June 28, 1972 the ice floe with North Pole-19 passed over the North Pole for the first time ever.

During such long-term observations by "NP" stations, a lot of important discoveries in physical geography were made, valuable conclusions on regularities and the connection between processes in the polar region of the Earth's hydrosphere and atmosphere were obtained. Some of the most important discoveries were finding the deep-water Lomonosov Ridge, which crosses the Arctic Ocean, other large features of the ocean bottom's relief, the discovery of two systems of the drift (circular and "wash-out"), the fact of cyclones' active penetration into the Central Arctic.

The last Soviet "NP" station, North Pole-31, was closed in July 1991.

In the post-Soviet era, Russian exploration of the Arctic by drifting ice stations was suspended for twelve years. The year 2003 was notable for Russia's return into the Arctic. As of 2006, three "NP" stations had carried out scientific measurements and research since then: "NP-32" through "NP-34". The latter was closed on May 25, 2006.

"NP-35" started operations on September 21, 2007 at the point 81°26'N 103°30'E, when flags of Russia and Saint Petersburg were raised there. 22 scientists, led by A.A.Visnevsky are working on the ice floe. Establishment of the station was the third stage of the Arktika 2007 expedition. An appropriate ice floe was searched for from Akademik Fedorov research vessel, accompanied by nuclear icebreaker Russia, using MI-8 helicopters, for a week, until an ice floe with an area of 16 square kilometres was found. The ice has since shrunk significantly, however, and the station is now being abandoned ahead of schedule.



5. ARCTIC OCEAN

The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying it a mediterranean sea or an estuary of the Atlantic Ocean. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean.

Almost completely surrounded by Eurasia and North America, the Arctic Ocean is partly covered by sea ice throughout the year (and almost completely in winter). The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy fresh water inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years.

5.1. HISTORY

For much of European history, the north polar regions remained largely unexplored and their geography conjectural. Pytheas of Massilia recorded an account of a journey northward in 325 BC, to a land he called "Eschate Thule," where the Sun only set for three hours each day and the water was replaced by a congealed substance "on which one can neither walk nor sail." He was probably describing loose sea ice known today as "growlers" or "bergy bits;" his "Thule" was probably Norway, though the Faroe Islands or Shetland have also been suggested.

Early cartographers were unsure whether to draw the region around the North Pole as land (as in Johannes Ruysch's map of 1507, or Gerardus Mercator's map of 1595) or water (as with Martin Waldseemüller's world map of 1507). The fervent desire of European merchants for a northern passage, the Northern Sea Route or the Northwest Passage, to "Cathay" (China) caused water to win out, and by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus Septentrionalis" at the northern edge of their charts.

The few expeditions to penetrate much beyond the Arctic Circle in this era added only small islands, such as Novaya Zemlya (11th century) and Spitsbergen (1596), though since these were often surrounded by pack-ice, their northern limits were not so clear. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in.

This lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an "Open Polar Sea" was persistent. John Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this.

In the United States in the 1850s and 1860s, the explorers Elisha Kane and Isaac Israel Hayes both claimed to have seen part of this elusive body of water. Even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea (1883). Nevertheless, as all the explorers who travelled closer and closer to the pole reported, the polar ice cap is quite thick, and persists year-round.

Fridtjof Nansen was the first to make a nautical crossing of the Arctic Ocean, in 1896. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard, with air support. The first nautical transit of the north pole was made in 1958 by the submarine USS Nautilus, and the first surface nautical transit occurred in 1977 by the icebreaker NS Arktika.

Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean. Scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes.

5.2. GEOGRAPHY

The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2, almost the size of Russia. The coastline is 45,390 km long. It is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands.

It is generally taken to include Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, East Siberian Sea, Greenland Sea, Hudson Bay, Hudson Strait, Kara Sea, Laptev Sea, White Sea and other tributary bodies of water. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea and Labrador Sea.

Countries bordering the Arctic Ocean are: Russia, Norway, Iceland, Greenland, Canada and the United States.

5.3. EXTENT AND MAJOR PORTS

5.3.1. UNITED STATES

In Alaska, the main ports are Barrow (71°17'44"N 156°45'59"W) and Prudhoe Bay (70°19'32"N 148°42'41"W).

5.3.2. CANADA

In Canada, ships may anchor at Churchill (Port of Churchill) (58°46'28"N 094°11'37"W) in Manitoba, Nanisivik (Nanisivik Naval Facility) (73°04'08"N 084°32'57"W) in Nunavut, Tuktoyaktuk (69°26'34"N 133°01'52"W) or Inuvik (68°21'42"N 133°43'50"W) in the Northwest territories.

5.3.3. GREENLAND

In Greenland, the main port is at Nuuk (Nuuk Port and Harbour) (64°10'15"N 051°43'15"W).

5.3.4. NORWAY

In Norway, Kirkenes (69°43'37"N 030°02'44"E) and Vardø (70°22'14"N 031°06'27"E) are ports on the mainland. Also, there is Longyearbyen (78°13'12"N 15°39'00"E) on the island of Svalbard next to Fram Strait.

5.3.5. RUSSIA

In Russia, major ports sorted by the different sea areas are:

Murmansk (68°58'N 033°05'E) in the Barents Sea
Arkhangelsk (64°32'N 040°32'E) in the White Sea
Labytnangi (66°39'26"N 066°25'06"E) Salekhard (66°32'N 066°36'E), Dudinka (69°24'N 086°11'E), Igarka (67°28'N 86°35'E) and Dikson (73°30'N 080°31'E) in the Kara Sea
Tiksi (71°38'N 128°52'E) in the Laptev Sea
Pevek (69°42'N 170°17'E) in the East Siberian Sea
5.4. ARCTIC SHELVES

The ocean's Arctic shelf comprises a number of continental shelves, including the Canadian Arctic shelf, underlying the Canadian Arctic Archipelago, and the Russian continental shelf, which is sometimes simply called the "Arctic Shelf" because it is greater in extent. The Russian continental shelf consists of three separate, smaller shelves, the Barents Shelf, Chukchi Sea Shelf and Siberian Shelf. Of these three, the Siberian Shelf is the largest such shelf in the world. The Siberian Shelf holds large oil and gas reserves, and the Chukchi shelf forms the border between Russian and the United States as stated in the USSR–USA Maritime Boundary Agreement. The whole area is subject to international territorial claims.

5.5. UNDERWATER FEATURES

An underwater ridge, the Lomonosov Ridge, divides the deep sea North Polar Basin into two oceanic basins: the Eurasian Basin, which is between 4,000 and 4,500 m (13,100 and 14,800 ft) deep, and the Amerasian Basin (sometimes called the North American, or Hyperborean Basin), which is about 4,000 m (13,000 ft) deep. The bathymetry of the ocean bottom is marked by fault block ridges, abyssal plains, ocean deeps, and basins. The average depth of the Arctic Ocean is 1,038 m (3,406 ft). The deepest point is Litke Deep in the Eurasian Basin, at 5,450 m (17,880 ft).

The two major basins are further subdivided by ridges into the Canada Basin (between Alaska/Canada and the Alpha Ridge), Makarov Basin (between the Alpha and Lomonosov Ridges), Nansen Basin (between Lomonosov and Gakkel ridges), and Nansen Basin (Amundsen Basin) (between the Gakkel Ridge and the continental shelf that includes the Franz Josef Land).

5.6. OCEANOGRAPHY

5.6.1. WATER FLOW


In large parts of the Arctic Ocean, the top layer (about 50 m (160 ft)) is of lower salinity and lower temperature than the rest. It remains relatively stable, because the salinity effect on density is bigger than the temperature effect. It is fed by the freshwater input of the big Siberian and Canadian streams (Ob, Yenisei, Lena, Mackenzie), the water of which quasi floats on the saltier, denser, deeper ocean water. Between this lower salinity layer and the bulk of the ocean lies the so-called halocline, in which both salinity and temperature are rising with increasing depth.

Due to its relative isolation from other oceans, the Arctic Ocean has a uniquely complex system of water flow. It is classified as a Mediterranean sea, which as “a part of the world ocean which has only limited communication with the major ocean basins (these being the Pacific, Atlantic, and Indian Oceans) and where the circulation is dominated by thermohaline forcing”. The Arctic Ocean has a total volume of 18.07×106 km3, equal to about 1.3% of the World Ocean. Mean surface circulation is predominately cyclonic on the Eurasian side and anticyclonic in the Canadian Basin.

Water enters from both the Pacific and Atlantic Oceans and can be divided into three unique water masses. The deepest water mass is called Arctic Bottom Water and begins around 900 meters depth. It is composed of the densest water in the World Ocean and has two main sources: Arctic shelf water and Greenland Sea Deep Water. Water in the shelf region that begins as inflow from the Pacific passes through the narrow Bering Strait at an average rate of 0.8 Sverdrups and reaches the Chukchi Sea. During the winter, cold Alaskan winds blow over the Chukchi Sea, freezing the surface water and pushing this newly formed ice out to the Pacific. The speed of the ice drift is roughly 1–4 cm/s. This process leaves dense, salty waters in the sea that sink over the continental shelf into the western Arctic Ocean and create a halocline.

This water is met by Greenland Sea Deep Water, which forms during the passage of winter storms. As temperatures cool dramatically in the winter, ice forms and intense vertical convection allows the water to become dense enough to sink below the warm saline water below. Arctic Bottom Water is critically important because of its outflow, which contributes to the formation of Atlantic Deep Water. The overturning of this water plays a key role in global circulation and the moderation of climate.

In the depth range of 150–900 meters is a water masses referred to as Atlantic Water. Inflow from the North Atlantic Current enters through the Fram Strait, cooling and sinking to form the deepest layer of the halocline, where it circles the Arctic Basin counter-clockwise. This is the highest volumetric inflow to the Arctic Ocean, equaling about 10 times that of the Pacific inflow, and it creates the Arctic Ocean Boundary Current. It flows slowly, at about 0.02 m/s. Atlantic Water has the same salinity as Arctic Bottom Water but is much warmer (up to 3 °C). In fact, this water mass is actually warmer than the surface water, and remains submerged only due the role of salinity in density. When water reaches the basin it is pushed by strong winds into a large circular current called the Beaufort Gyre. Water in the Beaufort Gyre is far less saline than that of the Chukchi Sea due to inflow from large Canadian and Siberian rivers.

The final defined water mass in the Arctic Ocean is called Arctic Surface Water and is found from 150–200 meters. The most important feature of this water mass is a section referred to as the sub-surface layer. It is a product of Atlantic water that enters through canyons and is subjected to intense mixing on the Siberian Shelf. As it is entrained, it cools and acts a heat shield for the surface layer. This insulation keeps the warm Atlantic Water from melting the surface ice. Additionally, this water forms the swiftest currents of the Arctic, with speed of around 0.3-0.6 m/s. Complementing the water from the canyons, some Pacific water that does not sink to the shelf region after passing through the Bering Strait also contributes to this water mass.

Waters originating in the Pacific and Atlantic both exit through the Fram Strait between Greenland and Svalbard Island, which is about 2700 meters deep and 350 kilometers wide. This outflow is about 9 Sv. The width of the Fram Strait is what allows for both inflow and outflow on the Atlantic side of the Arctic Ocean. Because of this, it is influenced by the Coriolis force, which concentrates outflow to the East Greenland Current on the western side and inflow to the Norwegian Current on the eastern side. Pacific water also exits along the west coast of Greenland and the Hudson Strait (1-2 Sv), providing nutrients to the Canadian Archipelago.

As noted, the process of ice formation and movement is a key driver in Arctic Ocean circulation and the formation of water masses. With this dependence, the Arctic Ocean experiences variations due to seasonal changes in sea ice cover. Sea ice movement is the result of wind forcing, which is related to a number of meteorological conditions that the Arctic experiences throughout the year. For example, the Beaufort High—an extension of the Siberian High system—is a pressure system that drives the anticyclonic motion of the Beaufort Gyre. During the summer, this area of high pressure is pushed out closer to its Siberian and Canadian sides. In addition, there is a sea level pressure (SLP) ridge over Greenland that drives strong northerly winds through the Fram Strait, facilitating ice export. In the summer, the SLP contrast is smaller, producing weaker winds. A final example of seasonal pressure system movement is the low pressure system that exists over the Nordic and Barents Seas. It is an extension of the Icelandic Low, which creates cyclonic ocean circulation in this area. The low shifts to center over the North Pole in the summer. These variations in the Arctic all contribute to ice drift reaching its weakest point during the summer months. There is also evidence that the drift is associated with the phase of the Arctic Oscillation and Atlantic Multidecadal Oscillation.

5.7. SEA ICE

Much of the Arctic Ocean is covered by sea ice which varies in extent and thickness seasonally. The mean extent of the ice is decreasing since 1980 from the average winter value of 15,600,000 km2 (6,023,200 sq mi) at a rate of 3% per decade. The seasonal variations are about 7,000,000 km2 (2,702,700 sq mi) with the maximum in April and minimum in September. The sea ice is affected by wind and ocean currents which can move and rotate very large areas of ice. Zones of compression also arise, where the ice piles up to form pack ice.

Icebergs occasionally break away from northern Ellesmere Island, and icebergs are formed from glaciers in western Greenland and extreme northeastern Canada. These icebergs pose a hazard to ships, of which the Titanic is one of the most famous. Permafrost is found on most islands. The ocean is virtually icelocked from October to June, and the superstructure of ships are subject to icing from October to May. Before the advent of modern icebreakers, ships sailing the Arctic Ocean risked being trapped or crushed by sea ice (although the Baychimo drifted through the Arctic Ocean untended for decades despite these hazards).

5.8. CLIMATE

Under the influence of the Quaternary glaciation, the Arctic Ocean is contained in a polar climate characterized by persistent cold and relatively narrow annual temperature ranges. Winters are characterized by the polar night, cold and stable weather conditions, and clear skies; summers are characterized by continuous daylight (midnight sun), damp and foggy weather, and weak cyclones with rain or snow

The temperature of the surface of the Arctic Ocean is fairly constant, near the freezing point of seawater. Because the Arctic Ocean consists of saltwater the temperature must reach -1.8 °C (28.8 °F) before freezing occurs.

The density of sea water, in contrast to fresh water, increases as it nears the freezing point and thus it tends to sink. It is generally necessary that the upper 100–150 m (330–490 ft) of ocean water cools to the freezing point for sea ice to form. In the winter the relatively warm ocean water exerts a moderating influence, even when covered by ice. This is one reason why the Arctic does not experience the extreme temperatures seen on the Antarctic continent.

There is considerable seasonal variation in how much pack ice of the Arctic ice pack covers the Arctic Ocean. Much of the Arctic ice pack is also covered in snow for about 10 months of the year. The maximum snow cover is in March or April — about 20 to 50 cm (7.9 to 19.7 in) over the frozen ocean.

The climate of the Arctic region has varied significantly in the past. As recently as 55 million years ago, during the Paleocene–Eocene Thermal Maximum, the region reached an average annual temperature of 10–20 °C (50–68 °F). The surface waters of the northernmost Arctic ocean warmed, seasonally at least, enough to support tropical lifeforms requiring surface temperatures of over 22 °C (72 °F).

5.9. ANIMAL AND PLANT LIFE

Endangered marine species in the Arctic Ocean include walruses and whales. The area has a fragile ecosystem which is slow to change and slow to recover from disruptions or damage. Lion's mane jellyfish are abundant in the waters of the Arctic, and the banded gunnel is the only species of gunnel that lives in the ocean.

The Arctic Ocean has relatively little plant life except for phytoplankton. Phytoplankton are a crucial part of the ocean and there are massive amounts of them in the Arctic, where they feed on nutrients from rivers and the currents of the Atlantic and Pacific oceans. During summer, the sun is out day and night, thus enabling the phytoplankton to photosynthesize for long periods of time and reproduce quickly. However, the reverse is true in winter where they struggle to get enough light to survive.

5.10. NATURAL RESOURCES

Petroleum and natural gas fields, placer deposits, polymetallic nodules, sand and gravel aggregates, fish, seals and whales can all be found in abundance in the region.

The political dead zone near the center of the sea is also the focus of a mounting dispute between the United States, Russia, Canada, Norway, and Denmark. It is significant for the global energy market because it may hold 25% or more of the world's undiscovered oil and gas resources.

5.11. ENVIRONMENTAL CONCERNS

The Arctic ice pack is thinning, and in many years there is also a seasonal hole in the ozone layer. Reduction of the area of Arctic sea ice reduces the planet's average albedo, possibly resulting in global warming in a positive feedback mechanism. Research shows that the Arctic may become ice free for the first time in human history by 2040.

Warming temperatures in the Arctic may cause large amounts of fresh meltwater to enter the north Atlantic, possibly disrupting global ocean current patterns. Potentially severe changes in the Earth's climate might then ensue.

As the extent of sea ice diminishes and sea level rises, the effect of storms such as the Great Arctic Cyclone of 2012 on open water increases, as does possible salt-water damage to vegetation on shore at locations such as the Mackenzie's river delta as stronger storm surges become more likely.

Other environmental concerns relate to the radioactive contamination of the Arctic Ocean from, for example, Russian radioactive waste dump sites in the Kara Sea and Cold War nuclear test sites such as Novaya Zemlya. In addition, Shell planned to drill exploratory wells in the Chukchi and Beaufort seas during the summer of 2012, which environmental groups filed a lawsuit about in an attempt to protect native communities, endangered wildlife, and the Arctic Ocean in the event of a major oil spill.


6. CLIMATE OF THE ARCTIC

The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice (sea ice, glacial ice, or snow) year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface. Average January temperatures range from about -40 to 0 °C , and winter temperatures can drop below -50 °C over large parts of the Arctic. Average July temperatures range from about -10 to +10 °C , with some land areas occasionally exceeding 30 °C in summer.

The Arctic consists of ocean that is largely surrounded by land. As such, the climate of much of the Arctic is moderated by the ocean water, which can never have a temperature below -2 °C . In winter, this relatively warm water, even though covered by the polar ice pack, keeps the North Pole from being the coldest place in the Northern Hemisphere, and it is also part of the reason that Antarctica is so much colder than the Arctic. In summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise.

6.1. ORIGIN OF THE ARCTIC CLIMATE

It is possible that this is the first time in the Earth's history that both poles have been simultaneously ice-bound. This unusual climate was created in the Azolla event when fresh surface water in the Arctic Ocean caused a long term abundance of Azolla, a type of aquatic fern. Huge quantities of dead Azolla built up and formed sedimentary rock, much of which contains fossil fuels as a result of the carbon contained in the Azolla. This process caused global cooling as a result of a reduction in the greenhouse effect. Release of stored carbon into the atmosphere as a result of current fossil fuel use is thought by most climate scientists to be causing global warming, which threatens to destroy the climatic conditions necessary for the current Arctic climate. However, Earth is a dynamic system, wherein global warming and cooling occurs periodically based on multiple interacting stimuli.

6.2. OVERVIEW OF THE ARCTIC

There are different definitions of the Arctic. The most widely used definition, the area north of the Arctic Circle, where, on the June solstice, the sun does not set is used in astronomical and some geographical contexts. However, in a context of climate, the two most widely used definitions in this context are the area north of the northern tree line, and the area in which the average temperature of the warmest month is less than 10 °C , which are nearly coincident over most land areas (NSIDC).

This definition of the Arctic can be further divided into four different regions:

* The Arctic Basin includes the Arctic Ocean within the average minimum extent of sea ice.
* The Canadian Arctic Archipelago includes the large and small islands, except Greenland, on the Canadian side of the Arctic, and the waters between them.
* The entire island of Greenland, although its ice sheet and ice-free coastal regions have different climatic conditions.
* The Arctic waters that are not covered by sea ice in late summer, including Hudson Bay, Baffin Bay, Ungava Bay, the Davis, Denmark, Hudson and Bering Straits, and the Labrador, Norwegian, (ice-free all year), Greenland, Baltic, Barents (southern part ice-free all year), Kara, Laptev, Chukchi, Okhotsk, sometimes Beaufort and Bering Seas.

Moving inland from the coast over mainland North America and Eurasia, the moderating influence of the Arctic Ocean quickly diminishes, and the climate transitions from Arctic to subarctic, generally in less than 500 kilometres (300 mi), and often over a much shorter distance.

6.3. HISTORY OF ARCTIC CLIMATE OBSERVATION

Due to the lack of major population centres in the Arctic, weather and climate observations from the region tend to be widely spaced and of short duration compared to the midlatitudes and tropics. Though the Vikings explored parts of the Arctic over a millennium ago, and small numbers of people have been living along the Arctic coast for much longer, scientific knowledge about the region was slow to develop; the large islands of Severnaya Zemlya, just north of the Taymyr Peninsula on the Russian mainland, were not discovered until 1913, and not mapped until the early 1930s (Serreze and Barry, 2005).

6.3.1. EARLY EUROPEAN EXPLORATION

Much of the historical exploration of the Arctic was motivated by the search for the Northwest and Northeast Passages. Sixteenth- and seventeenth-century expeditions were largely driven by traders in search of these shortcuts between the Atlantic and the Pacific. These forays into the Arctic did not venture far from the North American and Eurasian coasts, and were unsuccessful at finding a navigable route through either passage.

National and commercial expeditions continued to expand the detail on maps of the Arctic through the eighteenth century, but largely neglected other scientific observations. Expeditions from the 1760s to the middle of the 19th century were also led astray by attempts to sail north because of the belief by many at the time that the ocean surrounding the North Pole was ice-free. These early explorations did provide a sense of the sea ice conditions in the Arctic and occasionally some other climate-related information.

By the early 19th century some expeditions were making a point of collecting more detailed meteorological, oceanographic, and geomagnetic observations, but they remained sporadic. Beginning in the 1850s regular meteorological observations became more common in many countries, and the British navy implemented a system of detailed observation (Serreze and Barry, 2005). As a result, expeditions from the second half of the nineteenth century began to provide a picture of the Arctic climate.

6.3.2. EARLY EUROPEAN OBSERVING EFFORTS

The first major effort by Europeans to study the meteorology of the Arctic was the First International Polar Year (IPY) in 1882 to 1883. Eleven nations provided support to establish twelve observing stations around the Arctic. The observations were not as widespread or long-lasting as would be needed to describe the climate in detail, but they provided the first cohesive look at the Arctic weather.

In 1884 the wreckage of the Jeanette, a ship abandoned three years earlier off Russia's eastern Arctic coast, was found on the coast of Greenland. This caused Fridtjof Nansen to realize that the sea ice was moving from the Siberian side of the Arctic to the Atlantic side. He decided to use this motion by freezing a specially designed ship, the Fram, into the sea ice and allowing it to be carried across the ocean. Meteorological observations were collected from the ship during its crossing from September 1893 to August 1896. This expedition also provided valuable insight into the circulation of the ice surface of the Arctic Ocean.

In the early 1930s the first significant meteorological studies were carried out on the interior of the Greenland Ice Sheet. These provided knowledge of perhaps the most extreme climate of the Arctic, and also the first suggestion that the ice sheet lies in a depression of the bedrock below (now known to be caused by the weight of the ice itself).

Fifty years after the first IPY, in 1932 to 1933, a second IPY was organized. This one was larger than the first, with 94 meteorological stations, but World War II delayed or prevented the publication of much of the data collected during it (Serreze and Barry 2005). Another significant moment in Arctic observing before World War II occurred in 1937 when the USSR established the first of over 30 North-Pole drifting stations. This station, like the later ones, was established on a thick ice floe and drifted for almost a year, its crew observing the atmosphere and ocean along the way.

6.3.3. COLD-WAR ERA OBSERVATIONS

Following World War II, the Arctic, lying between the USSR and North America, became a front line of the Cold War, inadvertently and significantly furthering our understanding of its climate. Between 1947 and 1957, the United States and Canadian governments established a chain of stations along the Arctic coast known as the Distant Early Warning Line (DEWLINE) to provide warning of a Soviet nuclear attack. Many of these stations also collected meteorological data.

The Soviet Union was also interested in the Arctic and established a significant presence there by continuing the North-Pole drifting stations. This program operated continuously, with 30 stations in the Arctic from 1950 to 1991. These stations collected data that are valuable to this day for understanding the climate of the Arctic Basin. This map shows the location of Arctic research facilities during the mid-1970s and the tracks of drifting stations between 1958 and 1975.

Another benefit from the Cold War was the acquisition of observations from United States and Soviet naval voyages into the Arctic. In 1958 an American nuclear submarine, the Nautilus was the first ship to reach the North Pole. In the decades that followed submarines regularly roamed under the Arctic sea ice, collecting sonar observations of the ice thickness and extent as they went. These data became available after the Cold War, and have provided evidence of thinning of the Arctic sea ice. The Soviet navy also operated in the Arctic, including a sailing of the nuclear-powered ice breaker Arktika to the North Pole in 1977, the first time a surface ship reached the pole.

Scientific expeditions to the Arctic also became more common during the Cold-War decades, sometimes benefiting logistically or financially from the military interest. In 1966 the first deep ice core in Greenland was drilled at Camp Century, providing a glimpse of climate through the last ice age. This record was lengthened in the early 1990s when two deeper cores were taken from near the center of the Greenland Ice Sheet. Beginning in 1979 the Arctic Ocean Buoy Program (the International Arctic Buoy Program since 1991) has been collecting meteorological and ice-drift data across the Arctic Ocean with a network of 20 to 30 buoys.

6.3.4. SATELLITE ERA

The end of the Soviet Union in 1991 led to a dramatic decrease in regular observations from the Arctic. The Russian government ended the system of drifting North Pole stations, and closed many of the surface stations in the Russian Arctic. Likewise the United States and Canadian governments cut back on spending for Arctic observing as the perceived need for the DEWLINE declined. As a result, the most complete collection of surface observations from the Arctic is for the period 1960 to 1990 (Serreze and Barry, 2005).

The extensive array of satellite-based remote-sensing instruments now in orbit has helped to replace some of the observations that were lost after the Cold War, and has provided coverage that was impossible without them. Routine satellite observations of the Arctic began in the early 1970s, expanding and improving ever since. A result of these observations is a thorough record of sea-ice extent in the Arctic since 1979; the decreasing extent seen in this record (NASA, NSIDC), and its possible link to anthropogenic global warming, has helped increase interest in the Arctic in recent years. Today's satellite instruments provide routine views of not only cloud, snow, and sea-ice conditions in the Arctic, but also of other, perhaps less-expected, variables, including surface and atmospheric temperatures, atmospheric moisture content, winds, and ozone concentration.

Civilian scientific research on the ground has certainly continued in the Arctic, and it is getting a boost from 2007 to 2009 as nations around the world increase spending on polar research as part of the third International Polar Year. During these two years thousands of scientists from over 60 nations will co-operate to carry out over 200 projects to learn about physical, biological, and social aspects of the Arctic and Antarctic (IPY).

Modern researchers in the Arctic also benefit from computer models. These pieces of software are sometimes relatively simple, but often become highly complex as scientists try to include more and more elements of the environment to make the results more realistic. The models, though imperfect, often provide valuable insight into climate-related questions that cannot be tested in the real world. They are also used to try to predict future climate and the effect that changes to the atmosphere caused by humans may have on the Arctic and beyond. Another interesting use of models has been to use them, along with historical data, to produce a best estimate of the weather conditions over the entire globe during the last 50 years, filling in regions where no observations were made (ECMWF). These reanalysis datasets help compensate for the lack of observations over the Arctic.

6.4. SOLAR RADIATION

Almost all of the energy available to the Earth's surface and atmosphere comes from the sun in the form of solar radiation (light from the sun, including invisible ultraviolet and infrared light). Variations in the amount of solar radiation reaching different parts of the Earth are a principal driver of global and regional climate. Averaged over a year, latitude is the most important factor determining the amount of solar radiation reaching the top of the atmosphere; the incident solar radiation decreases smoothly from the Equator to the poles. This variation leads to the most obvious observation of regional climate: temperature tends to decrease with increasing latitude.

In addition the length of each day, which is determined by the season, has a significant impact on the climate. The 24-hour days found near the poles in summer result in a large daily-average solar flux reaching the top of the atmosphere in these regions. On the June solstice 36% more solar radiation reaches the top of the atmosphere over the course of the day at the North Pole than at the Equator (Serreze and Barry, 2005). However in the six months from the September equinox to March equinox the North Pole receives no sunlight. Images from the NOAA's North Pole Web Cam illustrate Arctic daylight, darkness and the changing of the seasons.

The climate of the Arctic also depends on the amount of sunlight reaching the surface, and the amount that the surface absorbs are also important. Variations in the frequency of cloud cover can cause significant variations in the amount of solar radiation reaching the surface at locations with the same latitude. Changes in surface conditions, such as the appearance or disappearance of snow or sea ice, can cause large changes in the surface albedo, the fraction of the solar radiation reaching the surface that is reflected rather than absorbed.

6.4.1. WINTER

In the Arctic, during the winter months of November through February, the sun remains very low in the sky or does not rise at all. Where it does rise, the days are short, and the sun's low position in the sky means that, even at noon, not much energy is reaching the surface. Furthermore, most of the small amount of solar radiation that reaches the surface is reflected away by the bright snow cover. Cold snow reflects between 70% and 90% of the solar radiation that reaches it (Serreze and Barry, 2005), and most of the Arctic, with the exception of the ice-free parts of the sea, have snow covering the land or ice surface in winter. These factors result in a negligible input of solar energy to the Arctic in winter; the only things keeping the Arctic from continuously cooling all winter are the transport of warmer air and ocean water into the Arctic from the south and the transfer of heat from the subsurface land and ocean (both of which gain heat in summer and release it in winter) to the surface and atmosphere.

6.4.2. SPRING

Arctic days lengthen rapidly in March and April, and the sun rises higher in the sky during this time as well. Both of these changes bring more solar radiation to the Arctic during this period. During these early months of Northern Hemisphere spring most of the Arctic is still experiencing winter conditions, but with the addition of sunlight. The continued low temperatures, and the persisting snow cover, mean that this additional energy reaching the Arctic from the sun is slow to have a significant impact because it is mostly reflected away without warming the surface. By May, temperatures are rising, as 24-hour daylight reaches many areas, but most of the Arctic is still snow covered, so the Arctic surface reflects more than 70% of the sun's energy that reaches it over all areas but the Norwegian Sea and southern Bering Sea, where the ocean is ice free, and some of the land areas adjacent to these seas, where the moderating influence of the open water helps melt the snow early (Serreze and Barry, 2005).

In most of the Arctic the significant snow melt begins in late May or sometime in June. This begins a feedback, as melting snow reflects less solar radiation (50% to 60%) than dry snow, allowing more energy to be absorbed and the melting to take place faster. As the snow disappears on land, the underlying surfaces absorb even more energy, and begin to warm rapidly.

The interior of Greenland differs from the rest of the Arctic. The low springtime cloud frequency there and the high elevation, which reduces the amount of solar radiation absorbed or scattered by the atmosphere, combine to give this region the highest surface flux of solar radiation anywhere in the Arctic. However, the high elevation, and corresponding lower temperatures, help keep the bright snow from melting, limiting the warming effect of all this solar radiation.

6.4.3. SUMMER

At the North Pole on the June solstice, around 21 June, the sun circles overhead at 23.5° above the horizon. This marks noon in the Pole's year-long day; from then until the September equinox, the sun will slowly approach nearer and nearer the horizon, offering less and less solar radiation to the Pole. This period of setting sun also roughly corresponds to summer in the Arctic. The rest of the Arctic will have the sun get lower in the sky and receive progressively shorter days.


As the Arctic continues receiving energy from the sun during this time, the land, which is mostly free of snow by now, can warm up on clear days when the wind is not coming from the cold ocean. Over the Arctic Ocean the snow cover on the sea ice disappears and ponds of melt water start to form on the sea ice, further reducing the amount of sunlight the ice reflects and helping more ice melt. Around the edges of the Arctic Ocean the ice will melt and break up, exposing the ocean water, which absorbs almost all of the solar radiation that reaches it, storing the energy in the water column. By July and August, most of the land is bare and absorbs more than 80% of the sun's energy that reaches the surface. Where sea ice remains, in the central Arctic Basin and the straits between the islands in the Canadian Archipelago, the many melt ponds and lack of snow cause about half of the sun's energy to be absorbed (Serreze and Barry, 2005), but this mostly goes toward melting ice since the ice surface cannot warm above freezing.

Frequent cloud cover, exceeding 80% frequency over much of the Arctic Ocean in July (Serreze and Barry, 2005), reduces the amount of solar radiation that reaches the surface by reflecting much of it before it gets to the surface. Unusual clear periods can lead to increased sea-ice melt or higher temperatures (NSIDC). The interior of Greenland continues to have less cloud cover than most of the Arctic, so during the summer period, like in spring, this area receives more solar radiation at the surface than any other part of the Arctic. Again though, interior Greenland's permanent snow cover reflects over 80% of this energy away from the surface.

6.4.4. AUTUMN

In September and October the days get rapidly shorter, and in northern areas the sun disappears from the sky entirely. As the amount of solar radiation available to the surface rapidly decreases, the temperatures follow suit. The sea ice begins to refreeze, and eventually gets a fresh snow cover, causing it to reflect even more of the dwindling amount of sunlight reaching it. Likewise, the northern land areas receive their winter snow cover, which combined with the reduced solar radiation at the surface, ensures an end to the warm days those areas may experience in summer. By November, winter is in full swing in most of the Arctic, and the small amount of solar radiation still reaching the region does not play a significant role in its climate.

6.5. TEMPERATURE

The Arctic is often perceived as a region stuck in a permanent deep freeze. While much of the region does experience very low temperatures, there is considerable variability with both location and season. Winter temperatures average below freezing over all of the Arctic except for small regions in the southern Norwegian and Bering Seas, which remain ice free throughout the winter. Average temperatures in summer are above freezing over all regions except the central Arctic Basin, where sea ice survives through the summer, and interior Greenland.

The maps at right show the average temperature over the Arctic in January and July, generally the coldest and warmest months. These maps were made with data from the NCEP/NCAR Reanalysis, which incorporates available data into a computer model to create a consistent global data set. Neither the models nor the data are perfect, so these maps may differ from other estimates of surface temperatures; in particular, most Arctic climatologies show temperatures over the central Arctic Ocean in July averaging just below freezing, a few degrees lower than these maps show (Serreze and Barry, 2005; USSR, 1985; CIA, 1978). An earlier climatology of temperatures in the Arctic, based entirely on available data, is shown in this map from the CIA Polar Regions Atlas (1978).

The coldest location in the Northern Hemisphere is not in the Arctic, but rather in the interior of Russia's Far East, in the upper-right quadrant of the maps. This is due to the region's continental climate, far from the moderating influence of the ocean, and to the valleys in the region that can trap cold, dense air and create strong temperature inversions, where the temperature increases, rather than decreases, with height (Serreze and Barry, 2005). The lowest officially recorded temperature in the Northern Hemisphere is the subject of controversy, due to the type of instrumentation used. These temperatures were measured by spirit thermometer, which is less accurate than a mercury thermometer. Measurement by spirit (alcohol) thermometers must be corrected (usually the correction is positive, being about 0.2°C, but it is not so simple). According to "Climate of the USSR, issue 24, part I, Leningrad, 1956," the coldest temperature of -67.7°C occurred in Oimyakon on 6 February 1933, as well as in Verkhoyansk on 5 and 7 February 1892, respectively. However, this region is not part of the Arctic because its continental climate also allows it to have warm summers, with an average July temperature of 15 °C . In the figure below showing station climatologies, the plot for Yakutsk is representative of this part of the Far East; Yakutsk has a slightly less extreme climate than Verkhoyansk.

6.5.1. ARCTIC BASIN

The Arctic Basin is typically covered by sea ice year round, which strongly influences its summer temperatures. It also experiences the longest period without sunlight of any part of the Arctic, and the longest period of continuous sunlight, though the frequent cloudiness in summer reduces the importance of this solar radiation.

Despite its location centered on the North Pole, and the long period of darkness this brings, this is not the coldest part of the Arctic. In winter, the heat transferred from the -2 °C water through cracks in the ice and areas of open water helps to moderate the climate some, keeping average winter temperatures around -30 to -35 °C . Minimum temperatures in this region in winter are around -50 °C .

In summer, the sea ice keeps the surface from warming above freezing. Sea ice is mostly fresh water since the salt is rejected by the ice as it forms, so the melting ice has a temperature of 0 °C , and any extra energy from the sun goes to melting more ice, not to warming the surface. Air temperatures, at the standard measuring height of about 2 meters above the surface, can rise a few degrees above freezing between late May and September, though they tend to be within a degree of freezing, with very little variability during the height of the melt season.

In the figure above showing station climatologies, the lower-left plot, for NP 7–8, is representative of conditions over the Arctic Basin. This plot shows data from the Soviet North Pole drifting stations, numbers 7 and 8. It shows the average temperature in the coldest months is in the -30s, and the temperature rises rapidly from April to May; July is the warmest month, and the narrowing of the maximum and minimum temperature lines shows the temperature does not vary far from freezing in the middle of summer; from August through December the temperature drops steadily. The small daily temperature range (the length of the vertical bars) results from the fact that the sun's elevation above the horizon does not change much or at all in this region during one day.

Much of the winter variability in this region is due to clouds. Since there is no sunlight, the thermal radiation emitted by the atmosphere is one of this region's main sources of energy in winter. A cloudy sky can emit much more energy toward the surface than a clear sky, so when it is cloudy in winter, this region tends to be warm, and when it is clear, this region cools quickly (Serreze and Barry, 2005).

6.5.2. CANADIAN ARCHIPELAGO

In winter, the Canadian Archipelago experiences temperatures similar to those in the Arctic Basin, but in the summer months of June to August, the presence of so much land in this region allows it to warm more than the ice-covered Arctic Basin. In the station-climatology figure above, the plot for Resolute is typical of this region. The presence of the islands, most of which lose their snow cover in summer, allows the summer temperatures to rise well above freezing. The average high temperature in summer approaches 10 °C , and the average low temperature in July is above freezing, though temperatures below freezing are observed every month of the year.

The straits between these islands often remain covered by sea ice throughout the summer. This ice acts to keep the surface temperature at freezing, just as it does over the Arctic Basin, so a location on a strait would likely have a summer climate more like the Arctic Basin, but with higher maximum temperatures because of winds off of the nearby warm islands.

6.5.3. GREENLAND

Climatically, Greenland is divided into two very separate regions: the coastal region, much of which is ice free, and the inland ice sheet. The Greenland Ice Sheet covers about 80% of Greenland, extending to the coast in places, and has an average elevation of 6,900 feet (2,100 m) and a maximum elevation of 10,500 feet (3,200 m). Much of the ice sheet remains below freezing all year, and it has the coldest climate of any part of the Arctic. Coastal areas can be affected by nearby open water, or by heat transfer through sea ice from the ocean, and many parts lose their snow cover in summer, allowing them to absorb more solar radiation and warm more than the interior.

Coastal regions on the northern half of Greenland experience winter temperatures similar to or slightly warmer than the Canadian Archipelago, with average January temperatures of -30 °C to -25 °C . These regions are slightly warmer than the Archipelago because of their closer proximity to areas of thin, first-year sea ice cover or to open ocean in the Baffin Bay and Greenland Sea.

The coastal regions in the southern part of the island are influenced more by open ocean water and by frequent passage of cyclones, both of which help to keep the temperature there from being as low as in the north. As a result of these influences, the average temperature in these areas in January is considerably higher, between about -20 °C and -4 °C .

The interior ice sheet escapes much of the influence of heat transfer from the ocean or from cyclones, and its high elevation also acts to give it a colder climate since temperatures tend to decrease with elevation. The result is winter temperatures that are lower than anywhere else in the Arctic, with average January temperatures of -45 °C to -30 °C , depending on location and on which data set is viewed. Minimum temperatures in winter over the higher parts of the ice sheet can drop below -60 °C (-76 °F; CIA, 1978). In the station climatology figure above, the Centrale plot is representative of the high Greenland Ice Sheet.

In summer, the coastal regions of Greenland experience temperatures similar to the islands in the Canadian Archipelago, averaging just a few degrees above freezing in July, with slightly higher temperatures in the south and west than in the north and east. The interior ice sheet remains snow covered throughout the summer, though significant portions do experience some snow melt (Serreze and Barry, 2005). This snow cover, combined with the ice sheet's elevation, help to keep temperatures here lower, with July averages between -12 °C and 0 °C . Along the coast, temperatures are kept from varying too much by the moderating influence of the nearby water or melting sea ice. In the interior, temperatures are kept from rising much above freezing because of the snow-covered surface but can drop to -30 °C even in July. Temperatures above 20°C are rare but do sometimes occur in the far south and south-west coastal areas.

6.5.4. ICE-FREE SEAS

Most of the ice-free seas are covered by ice for part of the year (see the map in the sea-ice section below). The exceptions are the southern part of the Bering Sea and most of the Norwegian Sea. These regions that remain ice-free throughout the year have very small annual temperature variations; average winter temperatures are kept near or above the freezing point of sea water (about -2 °C ) since the unfrozen ocean cannot have a temperature below that, and summer temperatures in the parts of these regions that are considered part of the Arctic average less than 10 °C . During the 46-year period when weather records were kept on Shemya Island, in the southern Bering Sea, the average temperature of the coldest month (February) was -0.6 °C and that of the warmest month (August) was 9.7 °C ; temperatures never dropped below -17 °C or rose above 18 °C.

The rest of the ice-free seas have ice cover for some part of the winter and spring, but lose that ice during the summer. These regions have summer temperatures between about 0 °C and 8 °C . The winter ice cover allows temperatures to drop much lower in these regions than in the regions that are ice-free all year. Over most of the seas that are ice-covered seasonally, winter temperatures average between about -30 °C and -15 °C . Those areas near the sea-ice edge will remain somewhat warmer due to the moderating influence of the nearby open water. In the station-climatology figure above, the plots for Point Barrow, Tiksi, Murmansk, and Isfjord are typical of land areas adjacent to seas that are ice-covered seasonally. The presence of the land allows temperatures to reach slightly more extreme values than the seas themselves.

6.6. PRECIPITATION

Precipitation in most of the Arctic falls as both rain and snow. Over most areas snow is the dominant, or only, form of precipitation in winter, while both rain and snow fall in summer (Serreze and Barry 2005). The main exception to this general description is the high part of the Greenland Ice Sheet, which receives all of its precipitation as snow, in all seasons.

Accurate climatologies of precipitation amount are more difficult to compile for the Arctic than climatologies of other variables such as temperature and pressure. All variables are measured at relatively few stations in the Arctic, but precipitation observations are made more uncertain due to the difficulty in catching in a gauge all of the snow that falls. Typically some falling snow is kept from entering precipitation gauges by winds, causing an underreporting of precipitation amounts in regions that receive a large fraction of their precipitation as snowfall. Corrections are made to data to account for this uncaught precipitation, but they are not perfect and introduce some error into the climatologies (Serreze and Barry 2005).

The observations that are available show that precipitation amounts vary by about a factor of 10 across the Arctic, with some parts of the Arctic Basin and Canadian Archipelago receiving less than 150 mm (6 in) of precipitation annually, and parts of southeast Greenland receiving over 1200 mm (47 in) annually. Most regions receive less than 500 mm (20 in) annually (Serreze and Hurst 2000, USSR 1985). For comparison, annual precipitation averaged over the whole planet is about 1000 mm (39 in; see Precipitation). Unless otherwise noted, all precipitation amounts given in this article are liquid-equivalent amounts, meaning that frozen precipitation is melted before it is measured.

6.6.1. ARCTIC BASIN

The Arctic Basin is one of the driest parts of the Arctic. Most of the Basin receives less than 250 mm (10 in) of precipitation per year, qualifying it as a desert. Smaller regions of the Arctic Basin just north of Svalbard and the Taymyr Peninsula receive up to about 400 mm (16 in) per year (Serreze and Hurst 2000).

Monthly precipitation totals over most of the Arctic Basin average about 15 mm (0.6 in) from November through May, and rise to 20 to 30 mm (0.8 to 1.2 in) in July, August, and September (Serreze and Hurst 2000). The dry winters result from the low frequency of cyclones in the region during that time, and the region's distance from warm open water that could provide a source of moisture (Serreze and Barry 2005). Despite the low precipitation totals in winter, precipitation frequency is higher in January, when 25% to 35% of observations reported precipitation, than in July, when 20% to 25% of observations reported precipitation (Serreze and Barry 2005). Much of the precipitation reported in winter is very light, possibly diamond dust. The number of days with measurable precipitation (more than 0.1 mm in a day) is slightly greater in July than in January (USSR 1985). Of January observations reporting precipitation, 95% to 99% of them indicate it was frozen. In July, 40% to 60% of observations reporting precipitation indicate it was frozen (Serreze and Barry 2005).

The parts of the Basin just north of Svalbard and the Taymyr Peninsula are exceptions to the general description just given. These regions receive many weakening cyclones from the North-Atlantic storm track, which is most active in winter. As a result, precipitation amounts over these parts of the basin are larger in winter than those given above. The warm air transported into these regions also mean that liquid precipitation is more common than over the rest of the Arctic Basin in both winter and summer.

6.6.2. CANADIAN ARCHIPELAGO
Annual precipitation totals in the Canadian Archipelago increase dramatically from north to south. The northern islands receive similar amounts, with a similar annual cycle, to the central Arctic Basin. Over Baffin Island and the smaller islands around it, annual totals increase from just over 200 mm (8 inches) in the north to about 500 mm (20 inches) in the south, where cyclones from the North Atlantic are more frequent (Serreze and Hurst 2000).

6.6.3. GREENLAND

Annual precipitation amounts given below for Greenland are from Figure 6.5 in Serreze and Barry (2005). Due to the scarcity of long-term weather records in Greenland, especially in the interior, this precipitation climatology was developed by analyzing the annual layers in the snow to determine annual snow accumulation (in liquid equivalent) and was modified on the coast with a model to account for the effects of the terrain on precipitation amounts.

The southern third of Greenland protrudes into the North-Atlantic storm track, a region frequently influenced by cyclones. These frequent cyclones lead to larger annual precipitation totals than over most of the Arctic. This is especially true near the coast, where the terrain rises from sea level to over 2500 m (8200 ft), enhancing precipitation due to orographic lift. The result is annual precipitation totals of 400 mm (16 in) over the southern interior to over 1200 mm (47 in) near the southern and southeastern coasts. Some locations near these coasts where the terrain is particularly conducive to causing orographic lift receive up 2200 mm (87 in) of precipitation per year. More precipitation falls in winter, when the storm track is most active, than in summer.

The west coast of the central third of Greenland is also influenced by some cyclones and orographic lift, and precipitation totals over the ice sheet slope near this coast are up to 600 mm (24 in) per year. The east coast of the central third of the island receives between 200 and 600 mm (8 and 24 in) of precipitation per year, with increasing amounts from north to south. Precipitation over the north coast is similar to that over the central Arctic Basin.

The interior of the central and northern Greenland Ice Sheet is the driest part of the Arctic. Annual totals here range from less than 100 to about 200 mm (4 to 8 in). This region is continuously below freezing, so all precipitation falls as snow, with more in summer than in winter (USSR 1985).

6.6.4. ICE-FREE SEAS

The Chukchi, Laptev, and Kara Seas and Baffin Bay receive somewhat more precipitation than the Arctic Basin, with annual totals between 200 and 400 mm (8 and 16 in); annual cycles in the Chukchi and Laptev Seas and Baffin Bay are similar to those in the Arctic Basin, with more precipitation falling in summer than in winter, while the Kara Sea has a smaller annual cycle due to enhanced winter precipitation caused by cyclones from the North Atlantic storm track (Serreze and Hurst 2000; Serreze and Barry 2005).

The Labrador, Norwegian, Greenland, and Barents Seas and Denmark and Davis Straits are strongly influenced by the cyclones in the North Atlantic storm track, which is most active in winter. As a result, these regions receive more precipitation in winter than in summer. Annual precipitation totals increase quickly from about 400 mm (16 in) in the northern to about 1400 mm (55 in) in the southern part of the region (Serreze and Hurst 2000). Precipitation is frequent in winter, with measurable totals falling on an average of 20 days each January in the Norwegian Sea (USSR 1985). The Bering Sea is influenced by the North Pacific storm track, and has annual precipitation totals between 400 mm and 800 mm (16 and 31 in), also with a winter maximum.

6.7. SEA ICE

Estimates of the absolute and average minimum and maximum extent of sea ice in the Arctic as of the mid-1970s
Sea ice is frozen sea water that floats on the ocean's surface. It is the dominant surface type throughout the year in the Arctic Basin, and covers much of the ocean surface in the Arctic at some point during the year. The ice may be bare ice, or it may be covered by snow or ponds of melt water, depending on location and time of year. Sea ice is relatively thin, generally less than about 4 m (13 feet), with thicker ridges (NSIDC). NOAA's North Pole Web Cams having been tracking the Arctic summer sea ice transitions through spring thaw, summer melt ponds, and autumn freeze-up since the first webcam was deployed in 2002–present.

Sea ice is important to the climate and the ocean in a variety of ways. It reduces the transfer of heat from the ocean to the atmosphere; it causes less solar energy to be absorbed at the surface, and provides a surface on which snow can accumulate, which further decreases the absorption of solar energy; since salt is rejected from the ice as it forms, the ice increases the salinity of the ocean's surface water where it forms and decreases the salinity where it melts, both of which can affect the ocean's circulation (NSIDC).

The map at right shows the areas covered by sea ice when it is at its maximum extent (March) and its minimum extent (September). This map was made in the 1970s, and the extent of sea ice has decreased since then (see below), but this still gives a reasonable overview. At its maximum extent, in March, sea ice covers about 15 million km² (5.8 million sq mi) of the Northern Hemisphere, nearly as much area as the largest country, Russia (UNEP 2007).

Winds and ocean currents cause the sea ice to move. The typical pattern of ice motion is shown on the map at right. On average, these motions carry sea ice from the Russian side of the Arctic Ocean into the Atlantic Ocean through the area east of Greenland, while they cause the ice on the North American side to rotate clockwise, sometimes for many years.

6.8. WIND

Wind speeds over the Arctic Basin and the western Canadian Archipelago average between 4 and 6 metres per second (14 and 22 kilometres per hour, 9 and 13 miles per hour) in all seasons. Stronger winds do occur in storms, often causing whiteout conditions, but they rarely exceed 25 m/s (90 km/h, 55 mph) in these areas (Przybylak 2003).

<<image_2>>

During all seasons, the strongest average winds are found in the North-Atlantic seas, Baffin Bay, and Bering and Chukchi Seas, where cyclone activity is most common. On the Atlantic side, the winds are strongest in winter, averaging 7 to 12 m/s (25 to 43 km/h, 16 to 27 mph), and weakest in summer, averaging 5 to 7 m/s (18 to 25 km/h, 11 to 16 mph). On the Pacific side they average 6 to 9 m/s (22 to 32 km/h, 13 to 20 mph) year round. Maximum wind speeds in the Atlantic region can approach 50 m/s (180 km/h, 110 mph) in winter (Przybylak 2003).

6.9. CLIMATE CHANGE

As with the rest of the planet, the climate in the Arctic has changed throughout time. About 55 million years ago it is thought that parts of the Arctic supported subtropical ecosystems (Serreze and Barry 2005) and that Arctic sea-surface temperatures rose to about 23 °C during the Paleocene–Eocene Thermal Maximum. In the more recent past, the planet has experienced a series of ice ages and interglacial periods over about the last 2 million years, with the last ice age reaching its maximum extent about 18,000 years ago and ending by about 10,000 years ago. During these ice ages, large areas of northern North America and Eurasia were covered by ice sheets similar to the one found today on Greenland; Arctic climate conditions would have extended much further south, and conditions in the present-day Arctic region were likely colder. Temperature proxies suggest that over the last 8000 years the climate has been stable, with globally averaged temperature variations of less than about 1 °C (2 °F; see Paleoclimate).

6.10. GLOBAL WARMING

There are several reasons to expect that climate changes, from whatever cause, may be enhanced in the Arctic, relative to the mid-latitudes and tropics. First, is the ice-albedo feedback, whereby an initial warming causes snow and ice to melt, exposing darker surfaces that absorb more sunlight, leading to more warming. Second, because colder air holds less water vapour than warmer air, in the Arctic, a greater fraction of any increase in radiation absorbed by the surface goes directly into warming the atmosphere, whereas in the tropics, a greater fraction goes into evaporation. Third, because the Arctic temperature structure inhibits vertical air motions, the depth of the atmospheric layer that has to warm in order to cause warming of near-surface air is much shallower in the Arctic than in the tropics. Fourth, a reduction in sea-ice extent will lead to more energy being transferred from the warm ocean to the atmosphere, enhancing the warming. Finally, changes in atmospheric and oceanic circulation patterns caused by a global temperature change may cause more heat to be transferred to the Arctic, enhancing Arctic warming (ACIA 2004).

According to the Intergovernmental Panel on Climate Change (IPCC), "warming of the climate system is unequivocal", and the global-mean temperature has increased by 0.6 to 0.9 °C over the last century. This report also states that "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations." The IPCC also indicate that, over the last 100 years, the annually averaged temperature in the Arctic has increased by almost twice as much as the global mean temperature has. In 2009, NASA reported that 45 percent or more of the observed warming in the Arctic since 1976 was likely a result of changes in tiny airborne particles called aerosols.

Climate models predict that the temperature increase in the Arctic over the next century will continue to be about twice the global average temperature increase. By the end of the 21st century, the annual average temperature in the Arctic is predicted to increase by 2.8 to 7.8 °C , with more warming in winter (4.3 to 11.4 °C) than in summer (IPCC 2007). Decreases in sea-ice extent and thickness are expected to continue over the next century, with some models predicting the Arctic Ocean will be free of sea ice in late summer by the mid to late part of the century (IPCC 2007).

A study published in the journal Science in September 2009 determined that temperatures in the Arctic are higher presently than they have been at any time in the previous 2,000 years. Samples from ice cores, tree rings and lake sediments from 23 sites were used by the team, led by Darrell Kaufman of Northern Arizona University, to provide snapshots of the changing climate. Geologists were able to track the summer Arctic temperatures as far back as the time of the Romans by studying natural signals in the landscape. The results highlighted that for around 1,900 years temperatures steadily dropped, caused by precession of earth's orbit that caused the planet to be slightly farther away from the sun during summer in the Northern Hemisphere. These orbital changes led to a cold period known as the little ice age during the 17th, 18th and 19th centuries. However, during the last 100 years temperatures have been rising, despite the fact that the continued changes in earth's orbit would have driven further cooling. The largest rises have occurred since 1950, with four of the five warmest decades in the last 2,000 years occurring between 1950 and 2000. The last decade was the warmest in the record.

 

[moidept]

Zwischenablage Löschen schon versucht ?
In der Tastatur auf die Drei Punkte gehen, dann Zwischenablage auswählen, auf Mülleimer,, dann auf alle Löschen, dann auf Löschen..

 

[Oi!Olli]

Jupp. Es kommt immer wieder.

Auch nach einem Neustart.

 

[maik005]

@Oi!Olli
Sieht auf den ersten Blick nach dem Text vom PCMark Benchmark Test aus.

 

[Wähler]

Ultima ratio: Gerät auf Werkseinstellungen zurücksetzen, neu aufsetzen.

 

[Oi!Olli]

@Oi!Olli
Sieht auf den ersten Blick nach dem Text vom PCMark Benchmark Test aus.

Das dürfte es sein. Der Akkutest lief auf meinem S10, da ich das gerade zum Verkauf fertig mache. In der dortigen Zwischenablage war auch noch ein im S20 kopierter Link drin.

Dann meine nächste Frage, wieso syncht sich meine Zwischenablage und wie schalte ich das aus?