Climate change in the Arctic

The consequences of global warming in the Arctic are among the regional impacts of global warming. Among them are significantly more than the global average rising air temperatures, retreating glaciers, permafrost and sea ice melting.

With a warmer Arctic accompanied numerous feedback loops, ie triggered by the warming changes that in turn affect the degree of warming. In addition to ecological consequences also have serious consequences for the people living in the Arctic people are expected.

Especially due to the decline of summer sea ice in a race of riparian States has evolved to the valuable resources that are assumed under the seabed of the Arctic Ocean beyond. Therefore, the environmental changes lead indirectly to political conflicts.

• 3.1 mass loss of Greenland
• 3.2 Isostatic dynamics
• 3.3 glacier dynamics
• 3.4 sea level rise by melt water
• 3.5 Possible changes in the ocean circulation

• 5.1 Tipping Point
• 5.2 Political conflicts
• 5.3 consequences for ecosystems

• 7.1 Rising methane emissions from thawing permafrost

Temperature increase

The period 1995-2005 was the warmest since at least the 17th century, and in 2005 was 2 ° C above the long-term average from 1951 to 1990 exceptionally warm. In addition to leading to global warming greenhouse gases probably also other components of air such as carbon black particles have contributed a significant part to this local heating. The soot is probably derived mostly from forest fires in boreal regions and smaller proportions of combusted fossil fuels.

In recent decades, the average air temperature in the Arctic increased about twice as fast as the global average temperature ( 1906-2005 ° C by 0.74 ± 0.18 ° C increased ). The area north of 60 ° N (about the height of Stockholm or Anchorage ) warmed up after a slight slowdown in the 1960s and 1970s until the end of the 20th century by an average of 1 to 2 ° C. Some regions, including Alaska and Western Canada, warmed since 1950 by 3 to 4 ° C. Since 1980, the Arctic is warming strongest in winter and spring, rising by about 1 ° C per decade. The lowest level is the heating in the fall. In addition, the members of the inner Arctic regions of North Asia and the north-west of North America to warm the most.

In the Arctic, in addition to the air and the water temperature increases much more rapidly as the global average. The water temperatures of the Arctic North Atlantic today are not as high as for at least 2000 years.

Higher temperatures due to polar amplification

An increase of the global concentration of greenhouse gases heated pole far more than other parts of the earth's surface. This ice - albedo feedback is causally Primarily: Snow and ice reflect most of the incident solar energy into space. The melting of the snow and brings Eisfächen underlying land and water surfaces to the fore, which absorb much of the sun's energy with their darker color. The surface is thereby further heated.

In the Arctic, the effect of the polar amplification in climate simulations, however, can be observed after only a few decades and the reason already measurable there strong warming. It is clearly visible in the form of declining glaciers, decreasing Arctic snow cover and sea ice cover. The effect not only on the immediate environment of the reduced albedo is limited. In a simulation, there was a three and a half fold increased warming of the western Arctic land areas in years with rapidly returning sea ice. The higher temperatures decreasing to 1500 kilometers into the interior.

Is reinforced by that in contrast to the Antarctic ice sheets of the Arctic are at sea level and even to a large extent in the sea. Due to the low altitude, the temperatures in large areas of the Arctic therefore much closer to the freezing point, which is why even small increases in temperature can initiate a melt. Sea ice is melted beyond not only from above (sun, air), but also from below, ie from heated ocean currents. Heats up the tundra, this leads to a change in the vegetation. Dark forests absorb much more solar energy than moss and lichen growth, which can be fully covered even at low precipitation advent of snow. This also supports a warming trend. In addition to the greenhouse gases that are responsible for global warming, delivered locally soot another problem dar. He is transported by the winds, is reflected in the low Arctic and darkens the surface of the gleaming white snow and ice.

Future warming

By the year 2100 is expected to further increase in the average air temperature in the Arctic by 2-9 ° C. For the whole earth is the authoritative in matters of climate research Intergovernmental Panel on Climate Change (IPCC ) is based on a contrast significantly lower heating 1.1 to 6.4 ° C. In the ( studied western ) Arctic comparable temperatures were last reached during the so-called Holocene temperature maximum 10,000 to 12,000 years ago, with the lower edge of these estimates. Back then there were the temperatures higher by 1.6 ± 0.8 ° C than the average for the 20th century. At that time, however, the warming took place over the course of at least two millennia, regional stepped up at different times and was probably " balanced " by the then existing Laurentide Ice Sheet over the Canada of today.

Increasing precipitation and " rain - on - snow events"

In the last century there were in the Arctic an increase in precipitation by about 8 %, mostly as rain. In autumn and winter, the increase was most pronounced here. However, the precipitation trends are locally very different and the measurements still quite inaccurate.

In the 21st century, a further increase in precipitation in the Arctic is expected. The commissioned by the Arctic Council in order Arctic Climate Impact Assessment ( ACIA ) predicts an increase in total precipitation by 20%. Particularly strong rainfall in the coastal areas will increase in the fall and winter.

According to the Arctic Climate Impact Assessment, it is already becoming more common to so-called " rain - on - snow events." Particularly the winter precipitation falls on the snow lying on the ground. This causes a rapid snow melt, and in some regions lead to acute flooding. In Western Russia came about such a " rain - on - snow events" by 50 % more often over the last 50 years.

The melting Greenland ice sheet

The second largest ice sheet on earth ( after Antarctica ) and the largest glacier in the Arctic region are located on Greenland. The Greenland ice sheet is one of the last remnants of the Pleistocene glaciation. He has survived because the ice -cooled by two feedback itself: First, it reflects a large part of the solar energy, without heating up this ( the so-called ice albedo feedback), and second, the surface of the mile- thick ice sheet is on high mountain level in colder layers of air.

Mass loss of Greenland

The temperatures in the south of the island have risen by 2.5 ° C since the mid-20th century. As a result, there was substantial decline in glaciers, melting larger inland areas and to an increasing mass loss.

In the higher central regions, the mass increases by increasing snowfall currently still.

The symbol for the loss of ice, a new island called Uunartoq Qeqertoq was (in English Warming Iceland ), which was discovered in 2005 on the east coast. After a large amount of land ice had melted, it turned out that it is not at Uunartoq Qeqertoq is inherent in the mainland peninsula, as had been previously thought.

The amount of ice melting is given in different units. A km ³ are a billion cubic meters and approximately ( due to the density anomaly ) a gigaton ( Gt) of ice.

The mass changes in Greenland are recorded with satellites ( eg GRACE, ICESat and Cryosat ). In the last 20 years, the melt has significantly strengthened. Overall, Greenland lost about 100 billion tons in 1996 to ground, a value comparable to the 1960s, while in 2007 almost 270 billion tons were lost. 2007 has been determined for the first time a negative mass balance for the height from 2000m.

From 2000 to 2008 inclusive, the total mass loss was about 1500 billion tons.

Different research teams are used in the analysis of satellite data to different results (see table), but all come to the unanimous conclusion that Greenland's mass decreases greatly.

In particular, the edges of Greenland are affected by an accelerated ice loss. The ice melt is also inland detectable. Between 1992 and 2005, the share of the Greenland area has with lockable ice melt increased by about 40,000 km2 per year, which now has about a quarter of the island of melting ice. A study conducted in 2011 investigated the mass loss of the Arctic and Antarctica and found out that in the period 1992-2009, each year 21.9 billion tons more ice melts in Greenland than in the previous year. For comparison, in Lake Constance are 48 billion tons of water.

The limit for a thinning of the Greenland ice sheets is according to a published study in 2012 from 0.8 to 3.2 degrees. The most likely value is 1.6 degrees. If global warming is to be limited to 2 degrees, the melting would take about 50,000 years with a possible, but unlikely warming by 8 degrees, however, only 2000 years.

July 12, 2012 satellite data showed that 97 % of the ice in Greenland melted, even 3000 meters high altitude areas. This has never been observed since the start of satellite observations; usually melts this time of year, about half of the ice. Eiskernanalysen show that the highlands of Greenland were last affected in 1889 by a thaw. Such an event takes place every 150 years on average. If the observed melting remain an isolated case, it would be nothing unusual in the context of statistics. Is such but seen again in the years to come, it meant a hitherto unexpected effect increased melting in this region.

Isostatic dynamics

As a result of melting glaciers Greenland rises slowly. Because the ice mass of the island decreases markedly reduces the Greenland oppressive weight. In recent years, the mainland lifted thereby predominantly in the coastal regions in places by up to 4 inches per year. Prior to 2004, this figure was only 0.5 to 1 cm. This let to the conclusion that the Greenland ice melt currently four times faster than even a few years ago, the scientists Shfaqat Khan from the Danish National Space Center.

Glacier dynamics

An individual glaciers of Greenland shows a surprising dynamic that (probably also due to lower research activity ) was generally unknown before the glaciers. Within days or weeks, the flow rate of a glacier can quadruple, then return back to the original level. In the long-term average has no general acceleration of the flow rate shown in some West Greenland glaciers. Two of the largest glacier on the island, Kangerdlugssuaq glacier and Helheim, who together contributed 35 % to the mass loss of East Greenland in recent years, were examined in detail by a team led by Ian Howat glaciologists. It was found that the melting rate of the two glaciers had doubled between 2004 and 2005. By 2006, the mass loss was then returned again to the value of 2004. A similar dynamic can also be observed on the right pictured Jakobshavn Isbræ on the west coast of Greenland. Between 2001 and 2003, its melting rate had accelerated dramatically and was then in 2004 declined significantly again. While the glacier had retreated 1991-1997 by an average of 15 meters per year, this figure had grown to 2003, to nearly double. Parallel accelerated the movement of his ice. Fraud whose rate in 1985 6.7 km per year from 1992 to 1997 just 5.7 km, this value increased significantly to 9.4 km per year for 2000 and further to 12.6 km in the year 2003. In 2004, the retreat was then significantly reduced again, reflecting the until today hardly predictable dynamics of Jakobshavn Isbræ.

Sea level rise by melt water

Between 1993 and 2003, the global sea level rise averaged 3.1 ± 0.7 mm according to satellite measurements per year. The ice sheet of Greenland, included a contribution of 0.21 ± 0.07 mm. By 2007, the global rise further increased to 3.3 ± 0.4 mm. The IPCC estimates that by 2100, increases in sea level between 0.19 m and 0.58 m are possible. The contribution of difficult to model ice sheets of Greenland and Antarctica thereof, however, expressly excluded, because the scientific understanding of its dynamics does not allow a reliable assessment.

Greenland ice mass is large enough to allow sea levels to rise worldwide over 7 m. One of today 's biggest foreseeable catastrophic consequences of global warming would therefore in a collapsing ice sheet. In recent years, estimates have been continuously revised downwards from when using a non- reversible re- dissolution process and how long it would last until the entire Greenland ice has melted. At the beginning of the 2000s, such a scenario was considered at best over the course of millennia possible. Today it is more consensus that this should be expected at most in centuries. The data published in recent years, data on rapid changes in the ice sheets suggest a dynamic that increasingly represents the image of huge contracts, ice in question.

In addition, 2006 and 2007 studies were published which minimize the loss of significant parts of the ice sheet even within a few decades for not excluded. This is the conclusion an article by Jonathan Overpeck et al. in the journal Science. This searches for climatic conditions in the climate history that are similar to those anticipated in this century. He will find it with the Eemian about 129000-118000 years ago. At that time the sea level was higher than today at least 4 and possibly 6 meters. The conditions in the Arctic, according to the authors, could be the end of the 21st century, which during the Eemian same. But if at that time, large parts of the Greenland ice sheet had melted, then could hardly be assumed that he would now be comparable to high temperatures without damage. NASA climatologist James E. Hansen warned as early as 2005 against a rapid rise in sea level as a result of melting ice sheets surprisingly fast. Hansen refers it to the occurred on the current warm period at the transition meltwater pulse 1A about 14200-14700 years ago. During the pulse, the sea level rose by 20 m within 400 to 500 years, or an average of one meter every 20 years. Hansen does not assume that a similar rapid rise of the oceans is very likely, however, he goes from one ( in the plural) " in meters " to be measured increase until the end of the 21st century.

Possible changes in the ocean circulation

There are several mechanisms which convey the heat generated by the sun's heat and energy flow from the equator to the poles. These include the globally interconnected movements of the water masses of the ocean. These movements occur due to differences in the temperature and salinity. This is known as thermohaline circulation.

Over the past 120,000 years, the North Atlantic current has been interrupted several times. The reason for this was probably each of the inflow of large amounts of fresh water, which weakened the compression process and prevented the decrease of the surface water. Theoretically, it is conceivable that the North Atlantic Current is interrupted again from the Greenland glaciers by the increased input of freshwater. A drying up of the Gulf Stream would have if no ice age, yet a strong cold snap across western and northern Europe result.

A break in the North Atlantic current is so far as at least the medium considered very unlikely by the researchers. By the end of the 21st century, a slight weakening of the North Atlantic Current is expected by simulations with climate models. In the course of investigations of the North Atlantic Current in the 2000s it became clear that this strong natural fluctuations, but so far has no signs of weakening.

The transported by altered atmospheric flow patterns in the Arctic winter 2005/2006 heating power was 90 terawatts, which is the output of 90,000 conventional nuclear power plants.

Returning glaciers outside Greenland

Also in other places in the Arctic glaciers begin to melt. Since 2000, went from the 40 glaciers in the 8100 km ² large Vatnajökull ice cap in Iceland, all but one back. In Iceland declined between 1995 and 2000 of 34 surveyed glaciers 28, four were stable and two grew.

In the Canadian Arctic Archipelago, there are numerous large ice caps. These include the Penny and Barneseiskappen on Baffin Island ( 507,451 km ² with the fifth largest island in the world ), the Byloteiskappe on Bylot Island ( 11,067 km ² ) and the Devoneiskappe on Devon Island ( 55,247 km ²). These ice caps are losing thickness and retreat slowly. Since the 1950s, over 20 ice sheets on Baffin Island have shrunk as a direct result of global warming by more than half, as a study by the University of Colorado at Boulder found. This is the smallest area for at least 1,600 years, according to the authors. The decline was all the more remarkable because natural factors such as the long-term inclination of the Earth to declining solar radiation in the Arctic have led and could have been expected an increase in the mass of ice in the sequence. The trend as in the past 50 years Set uniformly continued in the future, the complete disappearance of the ice sheets is expected no later than 2070 - a condition which was probably last been there in the mid- Holocene, 5000-8000 years ago. The Penny and Barneseiskappen have become thinner each year by more than 1 m alone between 1995 and 2000 in lower altitudes (below 1600 m). Overall, the ice caps of the Canadian Arctic between 1995 and 2000 have lost 25 km ³ of ice annually. Between 1960 and 1999, the Devoneiskappe has lost 67 ± 12 cubic kilometers of ice. The main glacier, stretching from the edge of the eastern Devoneiskappe have retreated by 1-3 km since 1960. The Simmoneiskappe on the Hazen Highland Ellesmere Island has lost 47 % of its area since 1959. Keep the current conditions, the remaining glacial ice will be gone on the Hazen highlands around 2050.

North of Norway is the island of Spitsbergen, which is covered by many glaciers. The Hansbreen glacier on Spitsbergen, for example, withdrew 1936-1982 to 1.4 km back. A further 400 m length he lost 1982-1998 Also the Blomstrandbreen has shortened. During the past 80 years, the length of the glacier has decreased by about 2 km. Since 1960, he retired with an average of 35 meters per year back, where the speed has increased since 1995. The Midre Lovenbreen Glacier has lost 1997-1995 200 m in length.

Shrinking Arctic Sea Ice

To observe the development of sea ice is not an easy task, as it varies greatly in thickness and density. Its surface area can be relatively easy to detect from satellites. Since the beginning of satellite measurements, the extent of sea ice in the Arctic is rapidly declining. Declining trends are observed in all regions and all months, the months with the strongest decline in September, July and August, the regions with the strongest decline in the Barents and Kara Sea resources. Reconstructions of the Arctic sea ice extent show that the current decline in sea ice extent, at least compared to the last few thousand years, extraordinary and not with the natural causes of past changes seem to be explainable.

At the start of satellite observations in 1979 and in subsequent years, the average extent of the ice was still about 7.5 million km2. Between 1979, the beginning of modern satellite observation and 2005 the observed ice area decreased by 1.5 to 2.0 % from per decade. The ice fall is generally in September most, it is traditionally the month with the smallest dimension; the Eisrückgang of this month 8.6 ± 2.9% per decade. If the examined period extended to non-observed with satellite years to 1953 to the rear, the decline is still 7.7 ± 0.6 % per decade.

The area loss accelerated significantly in the winters of 2005 and 2006. In these two years, the maximum extent of sea ice fell by 6 % - an increase by a factor 30 to 40 compared to previously determined in the decades melt rate.

Were significantly lower by 5.32 million km2 on 16 September 2007, 4.13 million km2, the lowest value of the record year 2005. The value for September 2007 was 4.28 million km2, about 23 % less than in 2005 and 39 % less than the average for the years 1979-2000.

Larger uncertainties in the detection of the thickness of the ice sheet, which is indispensable for the assessment of the situation. Here vary the data between 40% and 8 to 15 % decrease. In a press release from September 2007 on the occasion of the first results of an Arctic expedition aboard the research vessel Polarstern, the Alfred Wegener Institute for Polar and Marine Research writes ( AWI): " Large areas of the Arctic sea ice this year, only one meter thick, which is 50 percent thinner than in 2001. "

Zhang and Rothrock of the University of Washington using a complex numerical model ( PIOMAS ), which was fed with real data for flow, temperature, cloud cover and tested with measurements of ice thickness by submarines and by the satellite ICESat to the " white spots "fill on the map. Your result shows that when looking at the ice volume, the situation is much more alarming than when looking at the ice alone. The chart on the right speaks for itself

Since March 2013, large-scale measurement data for the ice thickness and thus the volume available for the first time. The European satellite CryoSat 2 measures with radar pulses the height difference between the ice surface and the sea surface in open areas between the ice floes. From this it can win its thickness considering the snow cover and the density of the ice. It is slightly larger than the calculated of PIOMAS, but also decreases rapidly.

As a result of Eisabschmelzung announced the European Space Agency on 14 September 2007, that since the beginning of satellite observations, the Northwest Passage was ice free for the first time. 2008 for the first time both the Northwest and the Northeast Passage were then in principle beschiffbar. The measured ice surface in summer 2008 was indeed slightly larger than in 2007, however, the ice thickness decreased further. While there is speculation in the media a lot about the future potential abbreviation of the sea route between Europe and Asia, should the winter Obstruction of passages and the real danger even in summer, to ram an iceberg, let the economic use for the near future remain marginal.

The IPCC was still in his latest report from the year 2007 assuming that by 2100 the North Pole in summer could be ice-free. However, none of the climate models had shown there for the next few years from a sea-ice loss, as he could already be observed in the Year of the Air report. A team led by researcher Marika Holland has determined in a model study in 2006 that the Arctic could be completely free of sea ice in the summer of 2040 for the first time. Together with her colleague Julienne Stroeve does not include Holland to a study published in 2007 even in 2020 as the first year of this. The European DAMOCLES project ( Developing Arctic modeling and observing capabilities for long -term environmental studies ) comes to the same result.

From an international research team, the circulation pattern of the atmosphere in the far north were examined in 2008; these have changed drastically at the beginning of this decade - with a systematic shift of air pressure centers to the northeast in the winter months. Thus, a pronounced atmosphere and ocean heat transport results in poleward. It is the driving force behind the current climate change in the Arctic.

In September 2012, the area of sea ice reached a new low, which fell short of the previous minimum of 2007 by 18 percent. The value of 2012 was with 3:41 million square kilometers, only half ( 51 percent ) of the average extent of the years 1979 to 2000 at the time of the annual minimum. The six lowest observed from satellites values ​​for the extent of Arctic sea ice were measured in the last six years (2007 to 2012).

Tipping Point

Systems with positive feedback can become unstable and behave sometimes nonlinear. It is believed that the Arctic may be a so-called tipping point in the global climate system is due to the ice - albedo feedback, further accelerated by the se heating strongly nonlinear and get high temperatures, even after reduction of a high concentration of greenhouse gases stay (hysteresis). Current research contradict this assumption, at least on short time scales: It is shown that the radiation in the winter months is of the order of the energy influx in the summer and a recovery of the ice less ice cover is possible in only a few years.

However, the views differ, as an Arctic Tipping Point is defined: If we look at this as a point at which a small change in the input parameters attracts a large effect by itself, the Arctic sea ice cover is reasonably anticipated to be the tipping point.

Political conflicts

The political status of the Arctic is not clarified until today concludes. Due to the decline of Arctic sea ice and the freed up access to raw materials below the seafloor associated conflicts between the riparian countries have experienced new relevance. To edit policy issues around the Arctic, the Arctic Council was established in 1996, but neither it nor in the relevant UN bodies has been able to reach an agreement.

The (geographic ) north and the of 300 km surrounding it up to a distance field are so far away from the mainland of the neighboring states, that they are not in possession of a state under current law. However, each state has the opportunity to request within ten years after the ratification of the Convention, under certain conditions, to extend its control on the continental shelf and thus to more than 200 nautical miles from the mainland. Because of this scheme applied previously Norway ( ratified UNCLOS 1996), Russia (1997 ), Canada ( 2003) and Denmark ( 2004), such an extension of their territory.

On 20 December 2001 Russia formally applied to the UN Commission on the Limits of the Continental Shelf ( CLCS ) in accordance with the Convention (Art. 76 sentence 8) establishing new external borders of the Russian continental shelf beyond 200 nautical miles wide exclusive economic zone, but within the Russian Arctic sector. The hereby claimed by Russia territory with an area of ​​approximately 1.2 million square kilometers represents a large part of the Arctic including the North Pole dar. The request was based, among other things, that both the Lomonosov and the Mendeleev Ridge submarine continuations of the Eurasian landmass were. The application has been neither accepted nor rejected by the United Nations. To reaffirm the Russian claim, appeared in early August 2007, two Russian submarines of type I to a depth of 4261 meters below sea level and set the geographic North Pole in a Russian flag on the seabed. While the diplomatic implications of this action were low, they created a significant media interest in the question of who owns the Arctic.

A special situation, the portion of the Arctic Ocean to the Canadian coast and the Canadian -Arctic Archipelago dar. Although these waters are actually Canadian partly under international law of the sea, do not recognize the United States, European Union and some other countries to the Canadian sovereignty, but use them as international waters. So on several occasions U.S. submarines were brought close to the Canadian islands by without previous request for authorization to the Government through Canadian territory. Although the affected waters, including the Northwest Passage counts, due to the extensive glaciation over nine months of the year, currently not very attractive for civilian and military shipping, but with continued melting of ice the Northwest Passage is for many ships a significant shortcut - up to 7000 nautical miles - compared to driving on the toll Central American Panama Canal represent.

The autonomous region belonging to Denmark Greenland is geographically the North Pole with its coastline on the next. Denmark claims that the area occupied by Russia Lomonosov Ridge in truth was a continuation of the island of Greenland. The Danish research in this field began with the expedition Lorita -1 in the spring of 2006. They will be continued within the framework of the International Polar Year in August 2007 with the company LOMROG. On August 12, 2007, went 40 scientists, including ten from Denmark, on board the Swedish icebreaker Oden, which expired from Tromsø to the north pole. While the Danish measurements should occupy the Copenhagen view that the continental shelf is connected to the pole with the island of Greenland, the Swedish participants study the climate history of the Arctic on the expedition.

Norway held initially largely from discussions on the status of the area around the North Pole out. It focused rather on his dispute with Russia over part of the Barents Sea and the status of Spitsbergen. On 27 November 2006 Norway handed but also an application to the CLCS one, proposed in the to expand the Norwegian 200 -mile zone in three areas of the North-East Atlantic and the Arctic Ocean: the Loophole in the Barents Sea, the western Nansen basin and the Banana Hole in the European North sea. It is noted that a further request may be submitted concerning the extension of the continental shelf in other areas.

For the U.S. government possible territorial gains play through the riparian status of the northernmost state of Alaska, a subordinate role because it would fall by the comparatively short coastline in all its procedures only a small area. The focus of the U.S. Arctic policy is rather directed to the Northeast and the Northwest Passage. These waters should be internationalized as far as possible the government under Bill Clinton and George W. Bush, according to open an unobstructed as possible navigation and more useful to them. Thus, they encountered resistance in Canada, Russia and the U.S. Senate, which rejected ratification of UNCLOS.

Consequences for ecosystems

If the Arctic sea ice is actually long-term and seasonal completely disappear, the disappearance of polar bears at least in some regions is possible by the Arctic Climate Impact Assessment considers. A similar conclusion also get Ian Stirling of the Canadian Wildlife Service and Claire L. Parkinson 's Goddard Space Flight Center of NASA in a 2006 published study, by increasing problematic confrontations between bears and humans as a result of diminishing habitats and rarified food supply of polar bears emanates. The U.S. Geological Survey is despite uncertain relationship between ice area and population size of a decline in the polar bear population by two thirds by 2050, should the sea ice decline as assumed in the models. Because the observed ice loss happens far faster than the models were suppose this could still represent an underestimate. Polar bears have, during the summer months as the only way to imitate the lifestyle of living on the mainland brown bears.

For other mammals such a serious break in the Arctic ecosystem would also have serious consequences. Chief among these are marine mammals that are very important for the present human communities. In a study of seven arctic and subarctic mammals four hooded seals, polar bears and narwhals as the animals most affected by climate change have been identified. Mainly due to their large habitat ringed seals and bearded seals are probably the least affected. Benefits would such a change may for some whale species that benefit from increasing open water.

Decreasing snow cover

Over the past 30 years, the snow-covered surface of the Arctic land areas has decreased by about 10%. According to model calculations, the snow cover will decrease to the 2070er years by an additional 10-20%. The largest decline is in this case expected in the months of April and May, which shortens the snow season. The water input by rivers into the Arctic Ocean and in the territorial waters should be earlier than today. Suppose is also that the freezing and melting cycles increase in winter and lead to increased formation of ice instead of snow layers. Land animals the achievement of food and breeding places is complicated.

Fading permafrost

The permafrost has been in the past few decades much warmer. In Alaska temperature rises to the surface to 5-7 ° C have been recorded since the beginning of the 20th century, the warming up to the mid-1980s stood at 2 to 4 ° C and 3 ° C since then more have been added. In addition to the surface also heats the upper soil layer. In the north- western Canada, an average warming of the uppermost 20 m of the permanently frozen soil there by 2 ° C during the last 20 years was determined. Lower temperature rise were also found in Siberia and Norway. From twelve of the Arctic Climate Impact Assessment regions has only a single a slight cooling between the late 1980s until the mid- 1990s, while the other eleven significantly heated part. In the course of the 21st century is expected that the southern edge of the continually frozen area will move several hundred kilometers to the north. By 2080, could be shrunk to 47-74 % of the present area, according to calculations with different climate models are constantly frozen ground surface.

Some consequences of thawing permafrost are coastal erosion, leakage or seepage ponds and lakes, wetlands and emerging large-scale development of thermokarst. These forests damaged by so-called are to be expected " drunken trees " to lose if previously anchored in frozen ground thawing trees in the mud to stop and run into trouble. For infrastructure, such as roads or pipelines that are built on permafrost to be reckoned with in considerable damage, especially if not continuously repair actions are not taken. This damage occurs partly already on, they force high expenditures in the affected regions.

It is estimated that Arctic permafrost contains about 30% of all the world's stored in soil carbon. In connection with the occurred in 2007, dramatic sea ice melt, the resulting warming of Arctic land areas was studied in periods of strong sea ice loss. Climate models show a warming of land that runs 3.5 times faster than the average, modeled for the 21st century warming during this time. The affected area extended 1500 km inland.

Rising methane emissions from thawing permafrost

In permafrost large amounts of carbon in the vast peat bogs of Siberia and parts of North America are bound. The boreal forest and the arctic tundra have some of the largest land reserves of carbon worldwide. These come in the form of plant material in the woods and as soil carbon in the tundra. The retreat of Arctic permafrost described above leads to the release of large amounts of the greenhouse gas methane, which in turn amplifies the global warming.

Drying Arctic Ponds

Probably as a result of global warming are some arctic ponds so-called Canadian Cape Herschel (on Ellesmere Island located ) for the summer of 2006 for the first time completely dried. The since 1983 by scientists John P. Smol and Marianne SV Douglas observed after ponds had paleolimnological analyzes at least several millennia uninterrupted period of water. Arctic ponds are small and relatively flat, particularly species-rich habitats. They are also one of the main sources of surface water and habitat for many birds and insects. Their disappearance is attributed to the increased ratio of evaporation to precipitation, a phenomenon that, according to the authors, " possibly with global warming related ." In the past, often sub-Arctic lakes have already disappeared, which could be explained by the receding permafrost. The Arctic ponds are, however, clearly evaporates as the increased salt concentration shows in not quite disappeared ponds with a greatly reduced amount of water.

Social Impact

In the Arctic, an estimated 3.8 million people, of which about 10% indigenous inhabitants. In the words of the Arctic Climate Impact Assessment, they are due to climate change " facing major economic and cultural consequences," and suffer the dangers and limitations of their food safety, health and her life. By declining sea ice, for example, Inuit hunters can no longer rely on traditional knowledge and hunting routes. It is alleged that accumulates the number of incidents in which people break through and drown to become thin sea ice.

As the access to food in each case, depend on safe travel routes, threaten dwindling sea ice melting permafrost or the existence of some human settlements in the Arctic. Both also influences the migration routes of reindeer and so the lifestyle of the people that depend on them. The traditionally hunted by the Inuit animals are also dependent on the previously prevailing conditions in the Arctic. This especially includes seals and walruses.

First villages in the Arctic had given up by thawing permafrost and several miles away to be rebuilt in Germany due to coastal erosion. For the future, increased coastal erosion by returning sea ice, rising sea levels and continue thawing soil. Was the relocation of entire villages so far limited to isolated cases, expects the Arctic Climate Impact Assessment with an increasing number of them in the future.