Climate change in the Arctic

The effects of global warming in the Arctic, or climate change in the Arctic include rising air and water temperatures, loss of sea ice, and melting of the Greenland ice sheet with a related cold temperature anomaly, observed since the 1970s.[1][2][3] Related impacts include ocean circulation changes, increased input of freshwater,[4][5] and ocean acidification.[6] Indirect effects through potential climate teleconnections to mid latitudes may result in a greater frequency of extreme weather events (flooding, fires and drought),[7] ecological, biological and phenology changes, biological migrations and extinctions,[8] natural resource stresses and as well as human health, displacement and security issues. Potential methane releases from the region, especially through the thawing of permafrost and methane clathrates, may occur.[9] Presently, the Arctic is warming twice as fast as the rest of the world.[10] The pronounced warming signal, the amplified response of the Arctic to global warming, is often seen as a leading indicator of global warming. The melting of Greenland's ice sheet is linked to polar amplification.[11][12] The warming in the Arctic is primarily caused by human-caused emissions of greenhouse gases such as carbon dioxide, methane, and nitrous oxide.

The image above shows where average air temperatures (October 2010 – September 2011) were up to 2 degrees Celsius above (red) or below (blue) the long-term average (1981–2010).
The maps above compare the Arctic ice minimum extents from 2012 (top) and 1984 (bottom). In 1984 the sea ice extent was roughly the average of the minimum from 1979 to 2000, and so was a typical year. The minimum sea ice extent in 2012 was roughly half of that average.

Rising temperatures

According to the Intergovernmental Panel on Climate Change, "warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world."[13] The period of 1995–2005 was the warmest decade in the Arctic since at least the 17th century, with temperatures 2 °C (3.6 °F) above the 1951–1990 average.[14] Some regions within the Arctic have warmed even more rapidly, with Alaska and western Canada's temperature rising by 3 to 4 °C (5.40 to 7.20 °F).[15] This warming has been caused not only by the rise in greenhouse gas concentration, but also the deposition of soot on Arctic ice.[16] A 2013 article published in Geophysical Research Letters has shown that temperatures in the region haven't been as high as they currently are since at least 44,000 years ago and perhaps as long as 120,000 years ago. The authors conclude that "anthropogenic increases in greenhouse gases have led to unprecedented regional warmth."[17][18]

On 20 June 2020, for the first time, a temperature measurement was made inside the Arctic Circle of 38 °C, more than 100 °F. This kind of weather was expected in the region only by 2100. In March, April and May the average temperature in the Arctic was 10 °C higher than normal.[19][20] This heat wave, without human - induced warming, could happen only one time in 80,000 years, according to an attribution study published in July 2020. It is the strongest link of a weather event to anthropogenic climate change that had been ever found, for now.[21] Such heat waves are generally a result of an unusual state of the jet stream. Some scientists suggest that climate change will slow the jet stream by reducing the difference in temperature between the Arctic and more southern territories, because the Arctic is warming faster. This can facilitate the occurring of such heat waves.[22] The scientists do not know if the 2020 heat wave is the result of such change.[23]

Arctic amplification
Main article: Arctic amplification

The poles of the Earth are more sensitive to any change in the planet's climate than the rest of the planet. In the face of ongoing global warming, the poles are warming faster than lower latitudes. The primary cause of this phenomenon is ice-albedo feedback where, by melting, ice uncovers darker land or ocean beneath, which then absorbs more sunlight, causing more heating.[24][25][26] The loss of the Arctic sea ice may represent a tipping point in global warming, when 'runaway' climate change starts,[27][28] but on this point the science is not yet settled.[29][30] According to a 2015 study, based on computer modelling of aerosols in the atmosphere, up to 0.5 degrees Celsius of the warming observed in the Arctic between 1980 and 2005 is due to aerosol reductions in Europe.[31]

Black carbon

Black carbon deposits (from the exhaust system of marine engines that often run on bunker fuel) reduce the albedo when deposited on snow and ice, and thus accelerate the effect of the melting of snow and sea ice.[32] A 2013 study quantified that gas flaring at petroleum extraction sites contributed over 40% of the black carbon deposited in the Arctic.[33][34]

According to a 2015 study, reductions in black carbon emissions and other minor greenhouse gases, by roughly 60 percent, could cool the Arctic up to 0.2 °C by 2050.[35]

Decline of sea ice
See also: Arctic sea ice decline

Sea ice is currently in decline in area, extent, and volume and summertime sea ice may cease to exist sometime during the 21st century. Sea ice area refers to the total area covered by ice, whereas sea ice extent is the area of ocean with at least 15% sea ice, while the volume is the total amount of ice in the Arctic.[36]

Changes in extent and area
1870–2009 Northern Hemisphere sea ice extent in million square kilometers. Blue shading indicates the pre-satellite era; data then is less reliable. In particular, the near-constant level extent in autumn up to 1940 reflects lack of data rather than a real lack of variation.

Reliable measurement of sea ice edges began with the satellite era in the late 1970s. Before this time, sea ice area and extent were monitored less precisely by a combination of ships, buoys and aircraft.[37] The data show a long-term negative trend in recent years, attributed to global warming, although there is also a considerable amount of variation from year to year.[38] Some of this variation may be related to effects such as the Arctic oscillation, which may itself be related to global warming.[39]

The Arctic sea ice September minimum extent (i.e., area with at least 15% sea ice coverage) reached new record lows in 2002, 2005, 2007, and 2012.[40] The 2007 melt season let to a minimum 39% below the 1979–2000 average, and for the first time in human memory, the fabled Northwest Passage opened completely.[41] The dramatic 2007 melting surprised and concerned scientists.[42][43]

Sea ice coverage in 1980 (bottom) and 2012 (top), as observed by passive microwave sensors on NASA's Nimbus-7 satellite and by the Special Sensor Microwave Imager/Sounder (SSMIS) from the Defense Meteorological Satellite Program (DMSP). Multi-year ice is shown in bright white, while average sea ice cover is shown in light blue to milky white. The data shows the ice cover for the period of 1 November through 31 January in their respective years.

From 2008 to 2011, Arctic sea ice minimum extent was higher than 2007, but it did not return to the levels of previous years.[44][45] In 2012 however, the 2007 record low was broken in late August with three weeks still left in the melt season.[46] It continued to fall, bottoming out on 16 September 2012 at 3.41 million square kilometers (1.32 million square miles), or 760,000 square kilometers (293,000 square miles) below the previous low set on 18 September 2007 and 50% below the 1979–2000 average.[47][48]

The rate of the decline in entire Arctic ice coverage is accelerating. From 1979 to 1996, the average per decade decline in entire ice coverage was a 2.2% decline in ice extent and a 3% decline in ice area. For the decade ending 2008, these values have risen to 10.1% and 10.7%, respectively. These are comparable to the September to September loss rates in year-round ice (i.e., perennial ice, which survives throughout the year), which averaged a retreat of 10.2% and 11.4% per decade, respectively, for the period 1979–2007.[49]

Changes in volume
Seasonal variation and long-term decrease of Arctic sea ice volume as determined by measurement backed numerical modelling.[50]

The sea ice thickness field and accordingly the ice volume and mass, is much more difficult to determine than the extension. Exact measurements can be made only at a limited number of points. Because of large variations in ice and snow thickness and consistency air- and spaceborne-measurements have to be evaluated carefully. Nevertheless, the studies made support the assumption of a dramatic decline in ice age and thickness.[45] While the Arctic ice area and extent show an accelerating downward trend, arctic ice volume shows an even sharper decline than the ice coverage. Since 1979, the ice volume has shrunk by 80% and in just the past decade the volume declined by 36% in the autumn and 9% in the winter.[51]

An end to summer sea ice?

The IPCC's Fourth Assessment Report in 2007 summarized the current state of sea ice projections: "the projected reduction [in global sea ice cover] is accelerated in the Arctic, where some models project summer sea ice cover to disappear entirely in the high-emission A2 scenario in the latter part of the 21st century.″ [52] However, current climate models frequently underestimate the rate of sea ice retreat.[53] A summertime ice-free Arctic would be unprecedented in recent geologic history, as currently scientific evidence does not indicate an ice-free polar sea anytime in the last 700,000 years.[54][55]

The Arctic ocean will likely be free of summer sea ice before the year 2100, but many different dates have been projected, with models showing near-complete to complete loss in September from 2035 to some time around 2067.[56][57]

Permafrost thaw
Rapidly thawing Arctic permafrost and coastal erosion on the Beaufort Sea, Arctic Ocean, near Point Lonely, AK. Photo Taken in August 2013
Permafrost thaw ponds on Baffin Island
Main article: Arctic methane release

Human caused climate change leads to higher temperatures that cause permafrost thawing in the Arctic. The thawing of the various types of Arctic permafrost could release large amounts of carbon into the atmosphere. In the permafrost there is twice as much carbon as in the atmosphere, but scientists estimate that no more than 100 billion tonnes will be released in the 21th century (humanity emit each year 40 billion).[58]

In 2019, a report called " Arctic report card " estimated the current greenhouse gas emissions from Arctic permafrost as almost equal to the emissions of Russia or Japan or less than 10% of the global emissions from fossil fuels.[59]

It has been estimated that about two-thirds of released carbon escapes to the atmosphere as carbon dioxide, originating primarily from ancient ice deposits along the ~7,000 kilometer long coastline of the East Siberian Arctic Shelf (ESAS) and shallow subsea permafrost. Following thaw, collapse and erosion of coastline and seafloor deposits may accelerate with Arctic amplification of climate warming.[60]

Climate models suggest that during periods of rapid sea-ice loss, temperatures could increase as far as 1,450 km (900 mi) inland, accelerating the rate of terrestrial permafrost thaw, with consequential effects on carbon and methane release.[61][62]

As of 2018, modeling of the permafrost carbon feedback has focused on gradual surface thawing, models have yet to account for deeper soil layers. A new study used field observations, radiocarbon dating, and remote sensing to account for thermokarst lakes, the authors concluded that, "..methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century."[63]

Thawing permafrost represents a threat to industrial infrastructure. In May 2020, permafrost melting due to climate change caused the worst oil spill to date in the Arctic. The melting of permafrost caused a collapse of a fuel tank, spilling 6,000 tonnes of diesel into the land, 15,000 into the water. The rivers Ambarnaya, Daldykan and many smaller rivers were polluted. The pollution reached the lake Pyasino that is important to the water supply of the entire Taimyr Peninsula. State of emergency at the federal level was declared. Many buildings and infrastructure are built on permafrost, which cover 65% of Russian territory, and all those can be damaged as it melts. The melting can also cause leakage of toxic elements from sites of buried toxic waste.[64][65]

Subsea permafrost
Main article: Clathrate gun hypothesis

Subsea permafrost occurs beneath the seabed and exists in the continental shelves of the polar regions.[66] This source of methane is different from methane clathrates, but contributes to the overall outcome and feedbacks.

Sea ice serves to stabilise methane deposits on and near the shoreline,[67] preventing the clathrate breaking down and venting into the water column and eventually reaching the atmosphere. From sonar measurements in recent years researchers quantified the density of bubbles emanating from the subsea permafrost into the Ocean (a process called ebullition), and found that 100–630 mg methane per square meters is emitted daily along the East Siberian Shelf, into the water column. They also found that during storms, methane levels in the water column drop dramatically, when wind-driven air-sea gas exchange accelerates the ebullition process into the atmosphere. This observed pathway suggests that methane from seabed permafrost will progress rather slowly, instead of abrupt changes. However, Arctic cyclones, fueled by global warming and further accumulation of greenhouse gases in the atmosphere could contribute to more release from this methane cache, which is really important for the Arctic.[68] An update to the mechanisms of this permafrost degradation, implying the possibility of being close to an acceleration of methane release was published in 2017.[69]

Changes in vegetation
Bloody Falls in July 2007.
Western Hemisphere Arctic Vegetation Index Trend
Eastern Hemisphere Vegetation Index Trend

Changes in vegetation are associated with the increases in landscape scale methane emissions.[70]

The growing season has lengthened in the far northern latitudes, bringing major changes to plant communities in tundra and boreal (also known as taiga) ecosystems.

For decades, NASA and NOAA satellites have continuously monitored vegetation from space. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High-Resolution Radiometer (AVHRR) instruments measure the intensity of visible and near-infrared light reflecting off of plant leaves. Scientists use the information to calculate the Normalized Difference Vegetation Index (NDVI), an indicator of photosynthetic activity or “greenness” of the landscape.

The maps above show the Arctic Vegetation Index Trend between July 1982 and December 2011 in the Arctic Circle. Shades of green depict areas where plant productivity and abundance increased; shades of brown show where photosynthetic activity declined. The maps show a ring of greening in the treeless tundra ecosystems of the circumpolar Arctic—the northernmost parts of Canada, Russia, and Scandinavia. Tall shrubs and trees started to grow in areas that were previously dominated by tundra grasses. The researchers concluded that plant growth had increased by 7 to 10 percent overall.

However, boreal forests, particularly those in North America, showed a different response to warming. Many boreal forests greened, but the trend was not as strong as it was for tundra of the circumpolar Arctic. In North America, some boreal forests actually experienced “browning” (less photosynthetic activity) over the study period. Droughts, forest fire activity, animal and insect behavior, industrial pollution, and a number of other factors may have contributed to the browning.

"Satellite data identify areas in the boreal zone that are warmer and drier and other areas that are warmer and wetter," explained co-author Ramakrishna Nemani of NASA's Ames Research Center. "Only the warmer and wetter areas support more growth."

"We found more plant growth in the boreal zone from 1982 to 1992 than from 1992 to 2011, because water limitations were encountered in the later two decades of our study," added co-author Sangram Ganguly of the Bay Area Environmental Research Institute and NASA Ames.[71]

The less severe winters in tundra areas allow shrubs such as alders and dwarf birch to replace moss and lichens. The impact on mosses and lichens is unclear as there exist very few studies at species level, also climate change is more likely to cause increased fluctuation and more frequent extreme events.[72] The feedback effect of shrubs on the tundra's permafrost is unclear. In the winter they trap more snow which insulates the permafrost from extreme cold spells, but in the summer they shade the ground from direct sunlight.[73] The warming is likely to cause changes in the plant communities.[74] Except for an increase in shrubs, warming may also cause a decline in cushion plants such as moss campion. Since cushion plants act as facilitator species across trophic level and fill important roles in severe environments this could cause cascading effects in the ecosystems.[75] Rising summer temperature melts on Canada's Baffin Island have revealed moss previously covered which has not seen daylight in 44,000 years.[76]

The reduction of sea ice has boosted the productivity of phytoplankton by about twenty percent over the past thirty years. However, the effect on marine ecosystems is unclear, since the larger types of phytoplankton, which are the preferred food source of most zooplankton, do not appear to have increased as much as the smaller types. So far, Arctic phytoplankton have not had a significant impact on the global carbon cycle.[77] In summer, the melt ponds on young and thin ice have allowed sunlight to penetrate the ice, in turn allowing phytoplankton to bloom in unexpected concentrations, although it is unknown just how long this phenomenon has been occurring.[78]

The increase of heat waves causes an increase in wildfires. In 2019 - 2020 the wildfires in Peatlands release more carbon to the atmosphere in 18 months than in the previous 16 years.[58]

The heat wave leaded to increase in the number of Siberian silk moths that damaged trees what help increase wildfires.[21]

Changes for animals
Further information: Effects of global warming on marine mammals

The northward shift of the subarctic climate zone is allowing animals that are adapted to that climate to move into the far north, where they are replacing species that are more adapted to a pure Arctic climate. Where the Arctic species are not being replaced outright, they are often interbreeding with their southern relations. Among slow-breeding vertebrate species, this often has the effect of reducing the genetic diversity of the genus. Another concern is the spread of infectious diseases, such as brucellosis or phocine distemper virus, to previously untouched populations. This is a particular danger among marine mammals who were previously segregated by sea ice.[79]

Projected change in polar bear habitat from 2001–2010 to 2041–2050

3 April 2007, the National Wildlife Federation urged the United States Congress to place polar bears under the Endangered Species Act.[80] Four months later, the United States Geological Survey completed a year-long study[81] which concluded in part that the floating Arctic sea ice will continue its rapid shrinkage over the next 50 years, consequently wiping out much of the polar bear habitat. The bears would disappear from Alaska, but would continue to exist in the Canadian Arctic Archipelago and areas off the northern Greenland coast.[82] Secondary ecological effects are also resultant from the shrinkage of sea ice; for example, polar bears are denied their historic length of seal hunting season due to late formation and early thaw of pack ice.

Some 200 Svalbard reindeer were found starved to death in July 2019, apparently due to low precipitation related to climate change.[83]

In the short-term, climate warming may have neutral or positive effects on the nesting cycle of many Arctic-breeding shorebirds.[84]

Melting of the Greenland ice sheet
Albedo Change on Greenland
Greenland ice sheet mass trend (2003–2005)

Models predict a sea-level contribution of about 5 centimetres (2 in) from melting of the Greenland ice sheet during the 21st century.[85] It is also predicted that Greenland will become warm enough by 2100 to begin an almost complete melt during the next 1,000 years or more.[86][87] In early July 2012, 97% percent of the ice sheet experienced some form of surface melt, including the summits.[88]

Ice thickness measurements from the GRACE satellite indicate that ice mass loss is accelerating. For the period 2002–2009, the rate of loss increased from 137 Gt/yr to 286 Gt/yr, with every year seeing on average 30 gigatonnes more mass lost than in the preceding year.[89] T

The rate of melting was 4 times higher in 2019 than in 2003. In the year 2019 the melting contributed 2.2 millimeters to sea level rise in just 2 months.[90][91]

The United States built a secret nuclear powered base, called Camp Century, in the Greenland ice sheet.[92] In 2016, a group of scientists evaluated the environmental impact and estimated that due to changing weather patterns over the next few decades, melt water could release the nuclear waste, 20,000 liters of chemical waste and 24 million liters of untreated sewage into the environment. However, so far neither US or Denmark has taken responsibility for the clean-up.[93]

According to a study published in "Nature Communications Earth and Environment" the Greenland ice sheet is possibly past the point of no return, meaning that even if the rise in temperature were to completely stop and even if the climate were to become a little colder the melting would continue. This is because the movement of ice from the middle of Greenland to the coast creates a larger contact between the ice and the warm water that leads to more melting and calving. Another climate scientist says that after all the ice near the coast melts, the contact between the seawater and the ice will stop what can prevent further warming.[90][91]

In September 2020, satellite imagery showed that a big chunk of ice shattered into many small pieces from the last remaining ice shelf in Nioghalvfjerdsfjorden, Greenland.[94]

Effect on ocean circulation
See also: Shutdown of thermohaline circulation and Ocean anoxic event

Although this is now thought unlikely in the near future, it has also been suggested that there could be a shutdown of thermohaline circulation, similar to that which is believed to have driven the Younger Dryas, an abrupt climate change event. There is also potentially a possibility of a more general disruption of ocean circulation, which may lead to an ocean anoxic event; these are believed to be much more common in the distant past. It is unclear whether the appropriate pre-conditions for such an event exist today.

Territorial claims
Main article: Territorial claims in the Arctic

Growing evidence that global warming is shrinking polar ice has added to the urgency of several nations' Arctic territorial claims in hopes of establishing resource development and new shipping lanes, in addition to protecting sovereign rights.[95]

Danish Foreign Minister Per Stig Møller and Greenland's Premier Hans Enoksen invited foreign ministers from Canada, Norway, Russia and the United States to Ilulissat, Greenland, for a summit in May 2008 to discuss how to divide borders in the changing Arctic region, and a discussion on more cooperation against climate change affecting the Arctic.[96] At the Arctic Ocean Conference, Foreign Ministers and other officials representing the five countries announced the Ilulissat Declaration on 28 May 2008.[97][98]

Social impacts

People are affecting the geographic space of the Arctic and the Arctic is affecting the population. Much of the climate change in the Arctic can be attributed to humans influences on the atmosphere, such as an increased greenhouse effect caused by the increase in CO
2 due to the burning of fossil fuels.[99] Climate change is having a direct impact on the people that live in the Arctic, as well as other societies around the world.[100]

The warming environment presents challenges to local communities such as the Inuit. Hunting, which is a major way of survival for some small communities, will be changed with increasing temperatures.[101] The reduction of sea ice will cause certain species populations to decline or even become extinct.[100] In good years, some communities are fully employed by the commercial harvest of certain animals.[101] The harvest of different animals fluctuates each year and with the rise of temperatures it is likely to continue changing and creating issues for Inuit hunters. Unsuspected changes in river and snow conditions will cause herds of animals, including reindeer, to change migration patterns, calving grounds, and forage availability.[100]

Other forms of transportation in the Arctic have seen negative impacts from the current warming, with some transportation routes and pipelines on land being disrupted by the melting of ice.[100] Many Arctic communities rely on frozen roadways to transport supplies and travel from area to area.[100] The changing landscape and unpredictability of weather is creating new challenges in the Arctic.[102]

researchers have documented historical and current trails created by the Inuit in the Pan Inuit Trails Atlas, finding that the change in sea ice formation and breakup has resulted in changes to the routes of trails created by the Inuit.[103]

The climate change in the Arctic is also affecting the quality and characteristics of snow which is used to build shelters such as igloos. It also provides unpredictable rain schedules and weather changes which impacts the people in Arctic in their daily lives. Since their tradition, culture, and knowledges are all developed within their ecosystems, the rapid climate change in Arctic affect the indigenous people living in Arctic requiring them to change such as identity and diet.

The Transpolar Sea Route is a future Arctic shipping lane running from the Atlantic Ocean to the Pacific Ocean across the center of the Arctic Ocean. The route is also sometimes called Trans-Arctic Route. In contrast to the Northeast Passage (including the Northern Sea Route) and the North-West Passage it largely avoids the territorial waters of Arctic states and lies in international high seas.[104]

Governments and private industry have shown a growing interest in the Arctic.[105] Major new shipping lanes are opening up: the northern sea route had 34 passages in 2011 while the Northwest Passage had 22 traverses, more than any time in history.[106] Shipping companies may benefit from the shortened distance of these northern routes. Access to natural resources will increase, including valuable minerals and offshore oil and gas.[100] Finding and controlling these resources will be difficult with the continually moving ice.[100] Tourism may also increase as less sea ice will improve safety and accessibility to the Arctic.[100]

The melting of Arctic ice caps is likely to increase traffic in and the commercial viability of the Northern Sea Route. One study, for instance, projects, "remarkable shifts in trade flows between Asia and Europe, diversion of trade within Europe, heavy shipping traffic in the Arctic and a substantial drop in Suez traffic. Projected shifts in trade also imply substantial pressure on an already threatened Arctic ecosystem."[107]

Research

National

Individual countries within the Arctic zone, Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden, and the United States (Alaska) conduct independent research through a variety of organizations and agencies, public and private, such as Russia's Arctic and Antarctic Research Institute. Countries who do not have Arctic claims, but are close neighbors, conduct Arctic research as well, such as the Chinese Arctic and Antarctic Administration (CAA). The United States's National Oceanic and Atmospheric Administration (NOAA) produces an Arctic Report Card annually, containing peer-reviewed information on recent observations of environmental conditions in the Arctic relative to historical records.[108][109]

International

International cooperative research between nations has become increasingly important:

See also

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