The Nelgese (Russian: Нельгесе ; Yakut : Нэльгэһэ , Nelgehe ) is a river in the Republic of Sakha in Russia . It is a left hand tributary of the Adycha , of the Yana basin. It is 566 kilometres (352 mi) long, with a drainage basin of 15,200 square kilometres (5,900 sq mi).
124-733: The river flows across a desolate area of severe climate, with continuous permafrost . The Nelgese is the longest tributary of the Adycha. It begins between two high ranges of the Verkhoyansk Range , running approximately from north to south to the west of the Khunkhadin Range . It heads roughly north across the Yana Plateau of the Yana-Oymyakon Highlands in a wide, swampy area dotted with ancient lakes. Then it turns northeast between
248-410: A carbon sink . As global warming heats the ecosystem, frozen soil thaws and becomes warm enough for decomposition to start anew, accelerating the permafrost carbon cycle . Depending on conditions at the time of thaw, decomposition can release either carbon dioxide or methane , and these greenhouse gas emissions act as a climate change feedback . The emissions from thawing permafrost will have
372-407: A 2022 review concluded that every 1 °C (1.8 °F) of global warming would cause 0.04 °C (0.072 °F) and 0.11 °C (0.20 °F) from abrupt thaw by the year 2100 and 2300. Around 4 °C (7.2 °F) of global warming, abrupt (around 50 years) and widespread collapse of permafrost areas could occur, resulting in an additional warming of 0.2–0.4 °C (0.36–0.72 °F). As
496-829: A 3.2% rise in global deforestation. Massive wildfires in Canada , exacerbated by climate change , contributed to a 24% increase in global tree cover loss, highlighting the ongoing threats to forests essential for carbon storage and biodiversity . Despite some progress, the overall trends in forest destruction and climate impacts remain off track. The IPCC Sixth Assessment Report stated in 2022: “Over 420 million ha of forest were lost to deforestation from 1990 to 2020; more than 90% of that loss took place in tropical areas (high confidence), threatening biodiversity, environmental services, livelihoods of forest communities and resilience to climate shocks (high confidence).” See also: Global deforestation sharply accelerated around 1852. As of 1947,
620-544: A climate where the mean annual soil surface temperature is between −5 and 0 °C (23 and 32 °F). In the moist-wintered areas mentioned before, there may not even be discontinuous permafrost down to −2 °C (28 °F). Discontinuous permafrost is often further divided into extensive discontinuous permafrost, where permafrost covers between 50 and 90 percent of the landscape and is usually found in areas with mean annual temperatures between −2 and −4 °C (28 and 25 °F), and sporadic permafrost, where permafrost cover
744-524: A fifth of both the industrial and the polluted sites (1000 and 2200–4800) are expected to start thawing in the future even if the warming does not increase from its 2020 levels. Only about 3% more sites would start thawing between now and 2050 under the climate change scenario consistent with the Paris Agreement goals, RCP2.6 , but by 2100, about 1100 more industrial facilities and 3500 to 5200 contaminated sites are expected to start thawing even then. Under
868-541: A further $ 1.32 billion. In particular, fewer than 20% of railways would be at high risk by 2100 under 1.5 °C (2.7 °F), yet this increases to 60% at 2 °C (3.6 °F), while under SSP5-8.5, this level of risk is met by mid-century. For much of the 20th century, it was believed that permafrost would "indefinitely" preserve anything buried there, and this made deep permafrost areas popular locations for hazardous waste disposal. In places like Canada's Prudhoe Bay oil field, procedures were developed documenting
992-633: A major climate tipping point in what was known as a clathrate gun hypothesis , but are now no longer believed to play any role in projected climate change. At the Last Glacial Maximum , continuous permafrost covered a much greater area than it does today, covering all of ice-free Europe south to about Szeged (southeastern Hungary ) and the Sea of Azov (then dry land) and East Asia south to present-day Changchun and Abashiri . In North America, only an extremely narrow belt of permafrost existed south of
1116-531: A minimum thickness of at least 2 m and a short diameter of at least 10 m. First recorded North American observations of this phenomenon were by European scientists at Canning River (Alaska) in 1919. Russian literature provides an earlier date of 1735 and 1739 during the Great North Expedition by P. Lassinius and Khariton Laptev , respectively. Russian investigators including I.A. Lopatin, B. Khegbomov, S. Taber and G. Beskow had also formulated
1240-466: A so-called active layer of soil which freezes and thaws depending on the season. Around 15% of the Northern Hemisphere or 11% of the global surface is underlain by permafrost, covering a total area of around 18 million km (6.9 million sq mi). This includes large areas of Alaska , Canada , Greenland , and Siberia . It is also located in high mountain regions, with
1364-532: A sufficient impact on the climate to impact global carbon budgets . It is difficult to accurately predict how much greenhouse gases the permafrost releases because of the different thaw processes are still uncertain. There is widespread agreement that the emissions will be smaller than human-caused emissions and not large enough to result in runaway warming . Instead, the annual permafrost emissions are likely comparable with global emissions from deforestation , or to annual emissions of large countries such as Russia ,
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#17329050448601488-605: A year. In 2006, the cost of adapting Inuvialuit homes to permafrost thaw was estimated at $ 208/m if they were built at pile foundations, and $ 1,000/m if they didn't. At the time, the average area of a residential building in the territory was around 100 m . Thaw-induced damage is also unlikely to be covered by home insurance , and to address this reality, territorial government currently funds Contributing Assistance for Repairs and Enhancements (CARE) and Securing Assistance for Emergencies (SAFE) programs, which provide long- and short-term forgivable loans to help homeowners adapt. It
1612-407: Is agreement that destruction of rainforests remains a significant environmental problem. The rate of net forest loss declined from 7.8 million ha per year in the decade 1990–2000 to 5.2 million ha per year in 2000–2010 and 4.7 million ha per year in 2010–2020. The rate of decline of net forest loss slowed in the most recent decade due to a reduction in the rate of forest expansion. In many parts of
1736-534: Is already considered "warm" permafrost, making it particularly unstable. Qinghai–Tibet Plateau has a population of over 10 million people – double the population of permafrost regions in the Arctic – and over 1 million m of buildings are located in its permafrost area, as well as 2,631 km of power lines , and 580 km of railways. There are also 9,389 km of roads, and around 30% are already sustaining damage from permafrost thaw. Estimates suggest that under
1860-473: Is also possible for subsurface alpine permafrost to be covered by warmer, vegetation-supporting soil. Alpine permafrost is particularly difficult to study, and systematic research efforts did not begin until the 1970s. Consequently, there remain uncertainties about its geography. As recently as 2009, permafrost had been discovered in a new area – Africa's highest peak, Mount Kilimanjaro (4,700 m (15,400 ft) above sea level and approximately 3° south of
1984-754: Is around 38%. Since 1960, roughly 15% of the Amazon has been removed with the intention of replacing the land with agricultural practices. It is no coincidence that Brazil has recently become the world's largest beef exporter at the same time that the Amazon rainforest is being clear cut. Another prevalent method of agricultural deforestation is slash-and-burn agriculture , which was primarily used by subsistence farmers in tropical regions but has now become increasingly less sustainable. The method does not leave land for continuous agricultural production but instead cuts and burns small plots of forest land which are then converted into agricultural zones. The farmers then exploit
2108-419: Is associated with a wide range of issues, and International Permafrost Association (IPA) exists to help address them. It convenes International Permafrost Conferences and maintains Global Terrestrial Network for Permafrost , which undertakes special projects such as preparing databases, maps, bibliographies, and glossaries, and coordinates international field programmes and networks. As recent warming deepens
2232-405: Is at risk by 2050, and that the associated costs could rise to tens of billions of dollars in the second half of the century. Furthermore, between 13,000 and 20,000 sites contaminated with toxic waste are present in the permafrost, as well as the natural mercury deposits, which are all liable to leak and pollute the environment as the warming progresses. Lastly, concerns have been raised about
2356-444: Is because carbon can be released through either aerobic or anaerobic respiration , which results in carbon dioxide (CO 2 ) or methane (CH 4 ) emissions, respectively. While methane lasts less than 12 years in the atmosphere, its global warming potential is around 80 times larger than that of CO 2 over a 20-year period and about 28 times larger over a 100-year period. While only a small fraction of permafrost carbon will enter
2480-399: Is covered by forests at present. This is one-third less than the forest cover before the expansion of agriculture, with half of that loss occurring in the last century. Between 15 million to 18 million hectares of forest, an area the size of Bangladesh , are destroyed every year. On average 2,400 trees are cut down each minute. Estimates vary widely as to the extent of deforestation in
2604-429: Is decreasing as well; as of 2019, ~97% of permafrost under Arctic ice shelves is becoming warmer and thinner. Based on high agreement across model projections, fundamental process understanding, and paleoclimate evidence, it is virtually certain that permafrost extent and volume will continue to shrink as the global climate warms, with the extent of the losses determined by the magnitude of warming. Permafrost thaw
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#17329050448602728-455: Is defined as a continuous permafrost zone, where 90%–100% of the land is underlain by permafrost. Around 20% is instead defined as discontinuous permafrost, where the coverage is between 50% and 90%. Finally, the remaining <30% of permafrost regions consists of areas with 10%–50% coverage, which are defined as sporadic permafrost zones, and some areas that have isolated patches of permafrost covering 10% or less of their area. Most of this area
2852-421: Is defined as the conversion of forest to other land uses (regardless of whether it is human-induced). Deforestation and forest area net change are not the same: the latter is the sum of all forest losses (deforestation) and all forest gains (forest expansion) in a given period. Net change, therefore, can be positive or negative, depending on whether gains exceed losses, or vice versa. The FAO estimates that
2976-497: Is difficult because the heat of the building (or pipeline ) can spread to the soil, thawing it. As ice content turns to water, the ground's ability to provide structural support is weakened, until the building is destabilized. For instance, during the construction of the Trans-Siberian Railway , a steam engine factory complex built in 1901 began to crumble within a month of operations for these reasons. Additionally, there
3100-605: Is estimated that some 420 million hectares of forest have been lost through conversion to other land uses , although the rate of deforestation has decreased over the past three decades. Between 2015 and 2020, the rate of deforestation was estimated at 10 million hectares per year, down from 16 million hectares per year in the 1990s. The area of primary forest worldwide has decreased by over 80 million hectares since 1990. More than 100 million hectares of forests are adversely affected by forest fires, pests, diseases, invasive species , drought and adverse weather events. Deforestation
3224-620: Is expected that cumulative greenhouse gas emissions from permafrost thaw will be smaller than the cumulative anthropogenic emissions, yet still substantial on a global scale, with some experts comparing them to emissions caused by deforestation . The IPCC Sixth Assessment Report estimates that carbon dioxide and methane released from permafrost could amount to the equivalent of 14–175 billion tonnes of carbon dioxide per 1 °C (1.8 °F) of warming. For comparison, by 2019, annual anthropogenic emissions of carbon dioxide alone stood around 40 billion tonnes. A major review published in
3348-420: Is expected to be lost "over decades and centuries". The exact amount of carbon that will be released due to warming in a given permafrost area depends on depth of thaw, carbon content within the thawed soil, physical changes to the environment, and microbial and vegetation activity in the soil. Notably, estimates of carbon release alone do not fully represent the impact of permafrost thaw on climate change. This
3472-435: Is expected to thaw, affecting all their inhabitants (currently 3.3 million people). Consequently, a wide range of infrastructure in permafrost areas is threatened by the thaw. By 2050, it's estimated that nearly 70% of global infrastructure located in the permafrost areas would be at high risk of permafrost thaw, including 30–50% of "critical" infrastructure. The associated costs could reach tens of billions of dollars by
3596-489: Is found in Siberia, northern Canada, Alaska and Greenland. Beneath the active layer annual temperature swings of permafrost become smaller with depth. The greatest depth of permafrost occurs right before the point where geothermal heat maintains a temperature above freezing. Above that bottom limit there may be permafrost with a consistent annual temperature—"isothermal permafrost". Permafrost typically forms in any climate where
3720-517: Is generated by radioactive decay of unstable isotopes and flows to the surface by conduction at a rate of ~47 terawatts (TW). Away from tectonic plate boundaries, this is equivalent to an average heat flow of 25–30 °C/km (124–139 °F/mi) near the surface. When the ice content of a permafrost exceeds 250 percent (ice to dry soil by mass) it is classified as massive ice. Massive ice bodies can range in composition, in every conceivable gradation from icy mud to pure ice. Massive icy beds have
3844-561: Is less than 50 percent of the landscape and typically occurs at mean annual temperatures between 0 and −2 °C (32 and 28 °F). In soil science, the sporadic permafrost zone is abbreviated SPZ and the extensive discontinuous permafrost zone DPZ . Exceptions occur in un-glaciated Siberia and Alaska where the present depth of permafrost is a relic of climatic conditions during glacial ages where winters were up to 11 °C (20 °F) colder than those of today. At mean annual soil surface temperatures below −5 °C (23 °F)
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3968-462: Is no groundwater available in an area underlain with permafrost. Any substantial settlement or installation needs to make some alternative arrangement to obtain water. A common solution is placing foundations on wood piles , a technique pioneered by Soviet engineer Mikhail Kim in Norilsk. However, warming-induced change of friction on the piles can still cause movement through creep , even as
4092-601: Is not an issue because of longer fallow periods and lesser overall deforestation. The relatively small size of the plots allowed for no net input of CO 2 to be released. Consumption and production of beef is the primary driver of deforestation in the Amazon , with around 80% of all converted land being used to rear cattle. 91% of Amazon land deforested since 1970 has been converted to cattle ranching. Livestock ranching requires large portions of land to raise herds of animals and livestock crops for consumer needs. According to
4216-454: Is possible that in the future, mandatory relocation would instead take place as the cheaper option. However, it would effectively tear the local Inuit away from their ancestral homelands. Right now, their average personal income is only half that of the median NWT resident, meaning that adaptation costs are already disproportionate for them. By 2022, up to 80% of buildings in some Northern Russia cities had already experienced damage. By 2050,
4340-453: Is projected to occur by the mid-21st century. In the early 2000s, some scientists predicted that unless significant measures (such as seeking out and protecting old growth forests that have not been disturbed) are taken on a worldwide basis, by 2030 there will only be 10% remaining, with another 10% in a degraded condition . 80% will have been lost, and with them hundreds of thousands of irreplaceable species. Estimates vary widely as to
4464-516: Is related to the tundra. Alpine permafrost also occurred in the Drakensberg during glacial maxima above about 3,000 metres (9,840 ft). Permafrost extends to a base depth where geothermal heat from the Earth and the mean annual temperature at the surface achieve an equilibrium temperature of 0 °C (32 °F). This base depth of permafrost can vary wildly – it is less than a meter (3 ft) in
4588-727: Is responsible for 48% of deforestation; commercial agriculture is responsible for 32%; logging is responsible for 14%, and fuel wood removals make up 5%. More than 80% of deforestation was attributed to agriculture in 2018. Forests are being converted to plantations for coffee, tea, palm oil , rice, rubber , and various other popular products. The rising demand for certain products and global trade arrangements causes forest conversions , which ultimately leads to soil erosion . The top soil oftentimes erodes after forests are cleared which leads to sediment increase in rivers and streams. Most deforestation also occurs in tropical regions. The estimated amount of total land mass used by agriculture
4712-595: Is subdivided into intrusive, injection and segregational ice. The latter is the dominant type, formed after crystallizational differentiation in wet sediments , which occurs when water migrates to the freezing front under the influence of van der Waals forces . This is a slow process, which primarily occurs in silts with salinity less than 20% of seawater : silt sediments with higher salinity and clay sediments instead have water movement prior to ice formation dominated by rheological processes. Consequently, it takes between 1 and 1000 years to form intrasedimental ice in
4836-461: Is that deforestation reduces the uptake of carbon dioxide ( carbon sequestration ) from the atmosphere. This reduces the potential of forests to assist with climate change mitigation . The role of forests in capturing and storing carbon and mitigating climate change is also important for the agricultural sector. The reason for this linkage is because the effects of climate change on agriculture pose new risks to global food systems . Since 1990, it
4960-433: Is the ongoing "greening" of the Arctic. As climate change warms the air and the soil, the region becomes more hospitable to plants, including larger shrubs and trees which could not survive there before. Thus, the Arctic is losing more and more of its tundra biomes, yet it gains more plants, which proceed to absorb more carbon. Some of the emissions caused by permafrost thaw will be offset by this increased plant growth, but
5084-482: Is under thick ice until the end of May. Average monthly flow of the Nelgese based on data collected between 1967 and 1997. Permafrost Permafrost (from perma- ' permanent ' and frost ) is soil or underwater sediment which continuously remains below 0 °C (32 °F) for two years or more: the oldest permafrost had been continuously frozen for around 700,000 years. Whilst
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5208-525: Is unknown. Notable sites with known ancient ice deposits include Yenisei River valley in Siberia , Russia as well as Banks and Bylot Island in Canada's Nunavut and Northwest Territories . Some of the buried ice sheet remnants are known to host thermokarst lakes . Intrasedimental or constitutional ice has been widely observed and studied across Canada. It forms when subterranean waters freeze in place, and
5332-545: The Congolese rainforest increased by 5%. The World Wildlife Fund 's ecoregion project catalogues habitat types throughout the world, including habitat loss such as deforestation, showing for example that even in the rich forests of parts of Canada such as the Mid-Continental Canadian forests of the prairie provinces half of the forest cover has been lost or altered. In 2011, Conservation International listed
5456-735: The Nelgesin Range and the Tirekhtyakh Range , flowing through a narrow valley before it joins the Adycha 78 km downstream from the mouth of the Derbeke and 13 km upstream from the mouth of the Charky . The Nelgese has many tributaries. The main ones are the Sordong and the Kordekan; the latter is the only one exceeding 100 km (62 mi) in length. The river freezes in late September or early October and
5580-694: The Northern and Southern Hemisphere are cold enough to support perennially frozen ground: some of the best-known examples include the Canadian Rockies , the European Alps , Himalaya and the Tien Shan . In general, it has been found that extensive alpine permafrost requires mean annual air temperature of −3 °C (27 °F), though this can vary depending on local topography , and some mountain areas are known to support permafrost at −1 °C (30 °F). It
5704-467: The Northern Hemisphere is ~145 centimetres (4.76 ft), but there are significant regional differences. Northeastern Siberia , Alaska and Greenland have the most solid permafrost with the lowest extent of active layer (less than 50 centimetres (1.6 ft) on average, and sometimes only 30 centimetres (0.98 ft)), while southern Norway and the Mongolian Plateau are the only areas where
5828-697: The Philippines , Indonesia , Thailand , Burma , Malaysia , Bangladesh , China, Sri Lanka , Laos , Nigeria , the Democratic Republic of the Congo , Liberia , Guinea , Ghana and the Ivory Coast , have lost large areas of their rainforest. Much of what remains of the world's rainforests is in the Amazon basin , where the Amazon Rainforest covers approximately 4 million square kilometres. Some 80% of
5952-460: The Pleistocene . Base depth is affected by the underlying geology, and particularly by thermal conductivity , which is lower for permafrost in soil than in bedrock . Lower conductivity leaves permafrost less affected by the geothermal gradient , which is the rate of increasing temperature with respect to increasing depth in the Earth's interior. It occurs as the Earth's internal thermal energy
6076-687: The Tibetan Plateau being a prominent example. Only a minority of permafrost exists in the Southern Hemisphere , where it is consigned to mountain slopes like in the Andes of Patagonia , the Southern Alps of New Zealand, or the highest mountains of Antarctica . Permafrost contains large amounts of dead biomass that have accumulated throughout millennia without having had the chance to fully decompose and release their carbon , making tundra soil
6200-532: The United States or China . Apart from its climate impact, permafrost thaw brings more risks. Formerly frozen ground often contains enough ice that when it thaws, hydraulic saturation is suddenly exceeded, so the ground shifts substantially and may even collapse outright. Many buildings and other infrastructure were built on permafrost when it was frozen and stable, and so are vulnerable to collapse if it thaws. Estimates suggest nearly 70% of such infrastructure
6324-470: The World Wildlife Fund , "Extensive cattle ranching is the number one culprit of deforestation in virtually every Amazon country, and it accounts for 80% of current deforestation." The cattle industry is responsible for a significant amount of methane emissions since 60% of all mammals on earth are livestock cows. Replacing forest land with pastures creates a loss of forest stock , which leads to
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#17329050448606448-504: The continental shelves of the polar regions. These areas formed during the last Ice Age , when a larger portion of Earth's water was bound up in ice sheets on land and when sea levels were low. As the ice sheets melted to again become seawater during the Holocene glacial retreat , coastal permafrost became submerged shelves under relatively warm and salty boundary conditions, compared to surface permafrost. Since then, these conditions led to
6572-403: The equator ). In 2014, a collection of regional estimates of alpine permafrost extent had established a global extent of 3,560,000 km (1,370,000 sq mi). Yet, by 2014, alpine permafrost in the Andes has not been fully mapped, although its extent has been modeled to assess the amount of water bound up in these areas. Subsea permafrost occurs beneath the seabed and exists in
6696-408: The ice sheet at about the latitude of New Jersey through southern Iowa and northern Missouri , but permafrost was more extensive in the drier western regions where it extended to the southern border of Idaho and Oregon . In the Southern Hemisphere , there is some evidence for former permafrost from this period in central Otago and Argentine Patagonia , but was probably discontinuous, and
6820-573: The pressure melting point throughout, may have liquid water at the interface with the ground and are therefore free of underlying permafrost. "Fossil" cold anomalies in the geothermal gradient in areas where deep permafrost developed during the Pleistocene persist down to several hundred metres. This is evident from temperature measurements in boreholes in North America and Europe. The below-ground temperature varies less from season to season than
6944-527: The southern hemisphere , most of the equivalent line would fall within the Southern Ocean if there were land there. Most of the Antarctic continent is overlain by glaciers, under which much of the terrain is subject to basal melting . The exposed land of Antarctica is substantially underlain with permafrost, some of which is subject to warming and thawing along the coastline. A range of elevations in both
7068-577: The tropics . In 2019, nearly a third of the overall tree cover loss, or 3.8 million hectares, occurred within humid tropical primary forests . These are areas of mature rainforest that are especially important for biodiversity and carbon storage . The direct cause of most deforestation is agriculture by far. More than 80% of deforestation was attributed to agriculture in 2018. Forests are being converted to plantations for coffee , palm oil , rubber and various other popular products. Livestock grazing also drives deforestation. Further drivers are
7192-574: The wood industry ( logging ), urbanization and mining . The effects of climate change are another cause via the increased risk of wildfires (see deforestation and climate change ). Deforestation results in habitat destruction which in turn leads to biodiversity loss . Deforestation also leads to extinction of animals and plants, changes to the local climate, and displacement of indigenous people who live in forests. Deforested regions often also suffer from other environmental problems such as desertification and soil erosion . Another problem
7316-454: The "appropriate" way to inject waste beneath the permafrost. This means that as of 2023, there are ~4500 industrial facilities in the Arctic permafrost areas which either actively process or store hazardous chemicals. Additionally, there are between 13,000 and 20,000 sites which have been heavily contaminated, 70% of them in Russia, and their pollution is currently trapped in the permafrost. About
7440-415: The 1990s. Between 2000 and 2018, the average active layer thickness had increased from ~127 centimetres (4.17 ft) to ~145 centimetres (4.76 ft), at an average annual rate of ~0.65 centimetres (0.26 in). In Yukon , the zone of continuous permafrost might have moved 100 kilometres (62 mi) poleward since 1899, but accurate records only go back 30 years. The extent of subsea permafrost
7564-419: The Arctic would enter life with weakened immune systems due to pollutants accumulating across generations. Deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms , ranches , or urban use. About 31% of Earth's land surface
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#17329050448607688-496: The United States, while under the scenario of high global warming and worst-case permafrost feedback response, they would approach year 2019 emissions of China. Fewer studies have attempted to describe the impact directly in terms of warming. A 2018 paper estimated that if global warming was limited to 2 °C (3.6 °F), gradual permafrost thaw would add around 0.09 °C (0.16 °F) to global temperatures by 2100, while
7812-412: The active layer subject to permafrost thaw, this exposes formerly stored carbon to biogenic processes which facilitate its entrance into the atmosphere as carbon dioxide and methane . Because carbon emissions from permafrost thaw contribute to the same warming which facilitates the thaw, it is a well-known example of a positive climate change feedback . Permafrost thaw is sometimes included as one of
7936-443: The air temperature, with mean annual temperatures tending to increase with depth due to the geothermal crustal gradient. Thus, if the mean annual air temperature is only slightly below 0 °C (32 °F), permafrost will form only in spots that are sheltered (usually with a northern or southern aspect , in the north and south hemispheres respectively) creating discontinuous permafrost. Usually, permafrost will remain discontinuous in
8060-429: The areas where it is shallowest, yet reaches 1,493 m (4,898 ft) in the northern Lena and Yana River basins in Siberia . Calculations indicate that the formation time of permafrost greatly slows past the first several metres. For instance, over half a million years was required to form the deep permafrost underlying Prudhoe Bay, Alaska , a time period extending over several glacial and interglacial cycles of
8184-511: The atmosphere as methane, those emissions will cause 40-70% of the total warming caused by permafrost thaw during the 21st century. Much of the uncertainty about the eventual extent of permafrost methane emissions is caused by the difficulty of accounting for the recently discovered abrupt thaw processes, which often increase the fraction of methane emitted over carbon dioxide in comparison to the usual gradual thaw processes. Another factor which complicates projections of permafrost carbon emissions
8308-554: The atmosphere, as well as the transfer of carbon between land and water as methane, dissolved organic carbon , dissolved inorganic carbon , particulate inorganic carbon and particulate organic carbon . Most of the bacteria and fungi found in permafrost cannot be cultured in the laboratory, but the identity of the microorganisms can be revealed by DNA -based techniques. For instance, analysis of 16S rRNA genes from late Pleistocene permafrost samples in eastern Siberia 's Kolyma Lowland revealed eight phylotypes , which belonged to
8432-439: The average active layer is deeper than 600 centimetres (20 ft), with the record of 10 metres (33 ft). The border between active layer and permafrost itself is sometimes called permafrost table. Around 15% of Northern Hemisphere land that is not completely covered by ice is directly underlain by permafrost; 22% is defined as part of a permafrost zone or region. This is because only slightly more than half of this area
8556-421: The coast of Tuktoyaktuk in western Arctic Canada , where the remains of Laurentide Ice Sheet are located. Buried surface ice may derive from snow, frozen lake or sea ice , aufeis (stranded river ice) and even buried glacial ice from the former Pleistocene ice sheets. The latter hold enormous value for paleoglaciological research, yet even as of 2022, the total extent and volume of such buried ancient ice
8680-405: The coldest regions, the depth of continuous permafrost can exceed 1,400 m (4,600 ft). It typically exists beneath the so-called active layer , which freezes and thaws annually, and so can support plant growth, as the roots can only take hold in the soil that's thawed. Active layer thickness is measured during its maximum extent at the end of summer: as of 2018, the average thickness in
8804-626: The commodity is consumed. For example, consumption patterns in G7 countries are estimated to cause an average loss of 3.9 trees per person per year. In other words, deforestation can be directly related to imports—for example, coffee. In 2023, the Global Forest Watch reported a 9% decline in tropical primary forest loss compared to the previous year, with significant regional reductions in Brazil and Colombia overshadowed by increases elsewhere, leading to
8928-469: The country's western regions at a rate of 15,000 hectares at a randomly studied 2-month period in 2010. In 2009, Paraguay's parliament refused to pass a law that would have stopped cutting of natural forests altogether. As of 2007, less than 50% of Haiti's forests remained . From 2015 to 2019, the rate of deforestation in the Democratic Republic of the Congo doubled. In 2021, deforestation of
9052-704: The damage to buildings ($ 2.8 billion), but there's also damage to roads ($ 700 million), railroads ($ 620 million), airports ($ 360 million) and pipelines ($ 170 million). Similar estimates were done for RCP4.5, a less intense scenario which leads to around 2.5 °C (4.5 °F) by 2100, a level of warming similar to the current projections. In that case, total damages from permafrost thaw are reduced to $ 3 billion, while damages to roads and railroads are lessened by approximately two-thirds (from $ 700 and $ 620 million to $ 190 and $ 220 million) and damages to pipelines are reduced more than ten-fold, from $ 170 million to $ 16 million. Unlike
9176-480: The damage to residential infrastructure may reach $ 15 billion, while total public infrastructure damages could amount to 132 billion. This includes oil and gas extraction facilities, of which 45% are believed to be at risk. Outside of the Arctic, Qinghai–Tibet Plateau (sometimes known as "the Third Pole"), also has an extensive permafrost area. It is warming at twice the global average rate, and 40% of it
9300-774: The decades 1990–2000 and 2000–2010. Some claim that rainforests are being destroyed at an ever-quickening pace. The London-based Rainforest Foundation notes that "the UN figure is based on a definition of forest as being an area with as little as 10% actual tree cover, which would therefore include areas that are actually savanna-like ecosystems and badly damaged forests". Other critics of the FAO data point out that they do not distinguish between forest types, and that they are based largely on reporting from forestry departments of individual countries, which do not take into account unofficial activities like illegal logging. Despite these uncertainties, there
9424-498: The deforestation of the Amazon can be attributed to cattle ranching, as Brazil is the largest exporter of beef in the world. The Amazon region has become one of the largest cattle ranching territories in the world. The regions with the highest tropical deforestation rate between 2000 and 2005 were Central America —which lost 1.3% of its forests each year—and tropical Asia. In Central America , two-thirds of lowland tropical forests have been turned into pasture since 1950 and 40% of all
9548-586: The discontinuous zone. Observed warming was up to 3 °C (5.4 °F) in parts of Northern Alaska (early 1980s to mid-2000s) and up to 2 °C (3.6 °F) in parts of the Russian European North (1970–2020). This warming inevitably causes permafrost to thaw: active layer thickness has increased in the European and Russian Arctic across the 21st century and at high elevation areas in Europe and Asia since
9672-431: The exact proportion is uncertain. It is considered very unlikely that this greening could offset all of the emissions from permafrost thaw during the 21st century, and even less likely that it could continue to keep pace with those emissions after the 21st century. Further, climate change also increases the risk of wildfires in the Arctic, which can substantially accelerate emissions of permafrost carbon. Altogether, it
9796-463: The extent of deforestation in the tropics. In 2019, the world lost nearly 12 million hectares of tree cover. Nearly a third of that loss, 3.8 million hectares, occurred within humid tropical primary forests, areas of mature rainforest that are especially important for biodiversity and carbon storage. This is equivalent to losing an area of primary forest the size of a football pitch every six seconds. A 2002 analysis of satellite imagery suggested that
9920-432: The form of charcoal or timber ), while cleared land is used as pasture for livestock and agricultural crops. The vast majority of agricultural activity resulting in deforestation is subsidized by government tax revenue . Disregard of ascribed value, lax forest management , and deficient environmental laws are some of the factors that lead to large-scale deforestation. The types of drivers vary greatly depending on
10044-469: The formation of frozen debris lobes (FDLs), which are defined as "slow-moving landslides composed of soil, rocks, trees, and ice". This is a notable issue in the Alaska 's southern Brooks Range , where some FDLs measured over 100 m (110 yd) in width, 20 m (22 yd) in height, and 1,000 m (1,100 yd) in length by 2012. As of December 2021, there were 43 frozen debris lobes identified in
10168-568: The global forest carbon stock has decreased 0.9%, and tree cover 4.2% between 1990 and 2020. As of 2019 there is still disagreement about whether the global forest is shrinking or not: "While above-ground biomass carbon stocks are estimated to be declining in the tropics, they are increasing globally due to increasing stocks in temperate and boreal forest. Deforestation in many countries —both naturally occurring and human-induced —is an ongoing issue. Between 2000 and 2012, 2.3 million square kilometres (890,000 square miles) of forests around
10292-425: The gradual and ongoing decline of subsea permafrost extent. Nevertheless, its presence remains an important consideration for the "design, construction, and operation of coastal facilities, structures founded on the seabed, artificial islands , sub-sea pipelines , and wells drilled for exploration and production". Subsea permafrost can also overlay deposits of methane clathrate , which were once speculated to be
10416-402: The implication of increased greenhouse gas emissions by burning agriculture methodologies and land-use change . A large contributing factor to deforestation is the lumber industry . A total of almost 4 million hectares (9.9 million acres) of timber, or about 1.3% of all forest land, is harvested each year. In addition, the increasing demand for low-cost timber products only supports
10540-411: The influence of aspect can never be sufficient to thaw permafrost and a zone of continuous permafrost (abbreviated to CPZ ) forms. A line of continuous permafrost in the Northern Hemisphere represents the most southern border where land is covered by continuous permafrost or glacial ice. The line of continuous permafrost varies around the world northward or southward due to regional climatic changes. In
10664-691: The largest annual rate of net forest loss in 2010–2020, at 3.9 million ha, followed by South America, at 2.6 million ha. The rate of net forest loss has increased in Africa in each of the three decades since 1990. It has declined substantially in South America, however, to about half the rate in 2010–2020 compared with 2000–2010. Asia had the highest net gain of forest area in 2010–2020, followed by Oceania and Europe. Nevertheless, both Europe and Asia recorded substantially lower rates of net gain in 2010–2020 than in 2000–2010. Oceania experienced net losses of forest area in
10788-430: The main driver of deforestation and forest fragmentation and the associated loss of forest biodiversity. Large-scale commercial agriculture (primarily cattle ranching and cultivation of soya bean and oil palm) accounted for 40 percent of tropical deforestation between 2000 and 2010, and local subsistence agriculture for another 33 percent. Trees are cut down for use as building material, timber or sold as fuel (sometimes in
10912-502: The major tipping points in the climate system due to the exhibition of local thresholds and its effective irreversibility. However, while there are self-perpetuating processes that apply on the local or regional scale, it is debated as to whether it meets the strict definition of a global tipping point as in aggregate permafrost thaw is gradual with warming. In the northern circumpolar region, permafrost contains organic matter equivalent to 1400–1650 billion tons of pure carbon, which
11036-574: The mean annual air temperature is lower than the freezing point of water. Exceptions are found in humid boreal forests , such as in Northern Scandinavia and the North-Eastern part of European Russia west of the Urals , where snow acts as an insulating blanket. Glaciated areas may also be exceptions. Since all glaciers are warmed at their base by geothermal heat, temperate glaciers , which are near
11160-460: The nutrients in the ashes of the burned plants. As well as, intentionally set fires can possibly lead to devastating measures when unintentionally spreading fire to more land, which can result in the destruction of the protective canopy. The repeated cycle of low yields and shortened fallow periods eventually results in less vegetation being able to grow on once burned lands and a decrease in average soil biomass. In small local plots sustainability
11284-500: The original 16 million square kilometres (6 million square miles) of tropical rainforest that formerly covered the Earth. More than 3.6 million hectares of virgin tropical forest was lost in 2018. The global annual net loss of trees is estimated to be approximately 10 billion. According to the Global Forest Resources Assessment 2020 the global average annual deforested land in the 2015–2020 demi-decade
11408-403: The original theories for ice inclusion in freezing soils. While there are four categories of ice in permafrost – pore ice, ice wedges (also known as vein ice), buried surface ice and intrasedimental (sometimes also called constitutional ) ice – only the last two tend to be large enough to qualify as massive ground ice. These two types usually occur separately, but may be found together, like on
11532-525: The other costs stemming from climate change in Alaska, such as damages from increased precipitation and flooding, climate change adaptation is not a viable way to reduce damages from permafrost thaw, as it would cost more than the damage incurred under either scenario. In Canada, Northwest Territories have a population of only 45,000 people in 33 communities, yet permafrost thaw is expected to cost them $ 1.3 billion over 75 years, or around $ 51 million
11656-418: The other hand, a 2005 analysis of satellite images reveals that deforestation of the Amazon rainforest is twice as fast as scientists previously estimated. From 2010 to 2015, worldwide forest area decreased by 3.3 million ha per year, according to FAO . During this five-year period, the biggest forest area loss occurred in the tropics, particularly in South America and Africa. Per capita forest area decline
11780-514: The other hands, disturbance of formerly hard soil increases drainage of water reservoirs in northern wetlands . This can dry them out and compromise the survival of plants and animals used to the wetland ecosystem. In high mountains, much of the structural stability can be attributed to glaciers and permafrost. As climate warms, permafrost thaws, decreasing slope stability and increasing stress through buildup of pore-water pressure, which may ultimately lead to slope failure and rockfalls . Over
11904-691: The past century, an increasing number of alpine rock slope failure events in mountain ranges around the world have been recorded, and some have been attributed to permafrost thaw induced by climate change. The 1987 Val Pola landslide that killed 22 people in the Italian Alps is considered one such example. In 2002, massive rock and ice falls (up to 11.8 million m ), earthquakes (up to 3.9 Richter ), floods (up to 7.8 million m water), and rapid rock-ice flow to long distances (up to 7.5 km at 60 m/s) were attributed to slope instability in high mountain permafrost. Permafrost thaw can also result in
12028-491: The phyla Actinomycetota and Pseudomonadota . "Muot-da-Barba-Peider", an alpine permafrost site in eastern Switzerland, was found to host a diverse microbial community in 2016. Prominent bacteria groups included phylum Acidobacteriota , Actinomycetota , AD3, Bacteroidota , Chloroflexota , Gemmatimonadota , OD1, Nitrospirota , Planctomycetota , Pseudomonadota , and Verrucomicrobiota , in addition to eukaryotic fungi like Ascomycota , Basidiomycota , and Zygomycota . In
12152-515: The pipeline from sinking and the Qingzang railway in Tibet employs a variety of methods to keep the ground cool, both in areas with frost-susceptible soil . Permafrost may necessitate special enclosures for buried utilities, called " utilidors ". Globally, permafrost warmed by about 0.3 °C (0.54 °F) between 2007 and 2016, with stronger warming observed in the continuous permafrost zone relative to
12276-410: The planet had 15 to 16 million km (5.8 to 6.2 million sq mi) of mature tropical forests , but by 2015, it was estimated that about half of these had been destroyed. Total land coverage by tropical rainforests decreased from 14% to 6%. Much of this loss happened between 1960 and 1990, when 20% of all tropical rainforests were destroyed. At this rate, extinction of such forests
12400-443: The potential for pathogenic microorganisms surviving the thaw and contributing to future pandemics . However, this is considered unlikely, and a scientific review on the subject describes the risks as "generally low". Permafrost is soil , rock or sediment that is frozen for more than two consecutive years. In practice, this means that permafrost occurs at a mean annual temperature of −2 °C (28.4 °F) or below. In
12524-595: The presence of permafrost. Black spruce tolerates limited rooting zones, and dominates flora where permafrost is extensive. Likewise, animal species which live in dens and burrows have their habitat constrained by the permafrost, and these constraints also have a secondary impact on interactions between species within the ecosystem . While permafrost soil is frozen, it is not completely inhospitable to microorganisms , though their numbers can vary widely, typically from 1 to 1000 million per gram of soil. The permafrost carbon cycle (Arctic Carbon Cycle) deals with
12648-534: The presently living species, scientists observed a variety of adaptations for sub-zero conditions, including reduced and anaerobic metabolic processes. There are only two large cities in the world built in areas of continuous permafrost (where the frozen soil forms an unbroken, below-zero sheet) and both are in Russia – Norilsk in Krasnoyarsk Krai and Yakutsk in the Sakha Republic . Building on permafrost
12772-488: The rainforests have been lost in the last 40 years. Brazil has lost 90–95% of its Mata Atlântica forest. Deforestation in Brazil increased by 88% for the month of June 2019, as compared with the previous year. However, Brazil still destroyed 1.3 million hectares in 2019. Brazil is one of several countries that have declared their deforestation a national emergency. Paraguay was losing its natural semi-humid forests in
12896-463: The rate of deforestation in the humid tropics (approximately 5.8 million hectares per year) was roughly 23% lower than the most commonly quoted rates. A 2005 report by the United Nations Food and Agriculture Organization (FAO) estimated that although the Earth's total forest area continued to decrease at about 13 million hectares per year, the global rate of deforestation had been slowing. On
13020-469: The region in which they take place. The regions with the greatest amount of deforestation for livestock and row crop agriculture are Central and South America, while commodity crop deforestation was found mainly in Southeast Asia. The region with the greatest forest loss due to shifting agriculture was sub-Saharan Africa. The overwhelming direct cause of deforestation is agriculture. Subsistence farming
13144-427: The scenario most similar to today, SSP2-4.5 , around 60% of the current infrastructure would be at high risk by 2090 and simply maintaining it would cost $ 6.31 billion, with adaptation reducing these costs by 20.9% at most. Holding the global warming to 2 °C (3.6 °F) would reduce these costs to $ 5.65 billion, and fulfilling the optimistic Paris Agreement target of 1.5 °C (2.7 °F) would save
13268-419: The second half of the century. Reducing greenhouse gas emissions in line with the Paris Agreement is projected to stabilize the risk after mid-century; otherwise, it'll continue to worsen. In Alaska alone, damages to infrastructure by the end of the century would amount to $ 4.6 billion (at 2015 dollar value) if RCP8.5 , the high-emission climate change scenario , were realized. Over half stems from
13392-409: The shallowest permafrost has a vertical extent of below a meter (3 ft), the deepest is greater than 1,500 m (4,900 ft). Similarly, the area of individual permafrost zones may be limited to narrow mountain summits or extend across vast Arctic regions. The ground beneath glaciers and ice sheets is not usually defined as permafrost, so on land, permafrost is generally located beneath
13516-513: The size of India—by 2050. 36% of globally planted forest area is in East Asia – around 950,000 square kilometers. From those 87% are in China. Rates of deforestation vary around the world. Up to 90% of West Africa 's coastal rainforests have disappeared since 1900. Madagascar has lost 90% of its eastern rainforests. In South Asia , about 88% of the rainforests have been lost. Mexico , India ,
13640-623: The soil remains frozen. The Melnikov Permafrost Institute in Yakutsk found that pile foundations should extend down to 15 metres (49 ft) to avoid the risk of buildings sinking. At this depth the temperature does not change with the seasons, remaining at about −5 °C (23 °F). Two other approaches are building on an extensive gravel pad (usually 1–2 m (3 ft 3 in – 6 ft 7 in) thick); or using anhydrous ammonia heat pipes . The Trans-Alaska Pipeline System uses heat pipes built into vertical supports to prevent
13764-668: The southern Brooks Range, where they could potentially threaten both the Trans Alaska Pipeline System (TAPS) corridor and the Dalton Highway , which is the main transport link between the Interior Alaska and the Alaska North Slope . As of 2021, there are 1162 settlements located directly atop the Arctic permafrost, which host an estimated 5 million people. By 2050, permafrost layer below 42% of these settlements
13888-470: The surface. However, only a fraction of this stored carbon is expected to enter the atmosphere. In general, the volume of permafrost in the upper 3 m of ground is expected to decrease by about 25% per 1 °C (1.8 °F) of global warming, yet even under the RCP8.5 scenario associated with over 4 °C (7.2 °F) of global warming by the end of the 21st century, about 5% to 15% of permafrost carbon
14012-537: The surrounding ground begins to jut outward at a slope. This can eventually result in the formation of large-scale land forms around this core of permafrost, such as palsas – long (15–150 m (49–492 ft)), wide (10–30 m (33–98 ft)) yet shallow (<1–6 m (3 ft 3 in – 19 ft 8 in) tall) peat mounds – and the even larger pingos , which can be 3–70 m (10–230 ft) high and 30–1,000 m (98–3,281 ft) in diameter . Only plants with shallow roots can survive in
14136-467: The top 10 most endangered forests, characterized by having all lost 90% or more of their original habitat , and each harboring at least 1500 endemic plant species (species found nowhere else in the world). As of 2015 , it is estimated that 70% of the world's forests are within one kilometer of a forest edge, where they are most prone to human interference and destruction. Deforestation in particular countries: Agricultural expansion continues to be
14260-859: The top 2.5 meters of clay sediments, yet it takes between 10 and 10,000 years for peat sediments and between 1,000 and 1,000,000 years for silt sediments. Permafrost processes such as thermal contraction generating cracks which eventually become ice wedges and solifluction – gradual movement of soil down the slope as it repeatedly freezes and thaws – often lead to the formation of ground polygons, rings, steps and other forms of patterned ground found in arctic, periglacial and alpine areas. In ice-rich permafrost areas, melting of ground ice initiates thermokarst landforms such as thermokarst lakes , thaw slumps, thermal-erosion gullies, and active layer detachments. Notably, unusually deep permafrost in Arctic moorlands and bogs often attracts meltwater in warmer seasons, which pools and freezes to form ice lenses , and
14384-435: The transfer of carbon from permafrost soils to terrestrial vegetation and microbes, to the atmosphere, back to vegetation, and finally back to permafrost soils through burial and sedimentation due to cryogenic processes. Some of this carbon is transferred to the ocean and other portions of the globe through the global carbon cycle. The cycle includes the exchange of carbon dioxide and methane between terrestrial components and
14508-424: The very high emission scenario RCP8.5, 46% of industrial and contaminated sites would start thawing by 2050, and virtually all of them would be affected by the thaw by 2100. Organochlorines and other persistent organic pollutants are of a particular concern, due to their potential to repeatedly reach local communities after their re-release through biomagnification in fish. At worst, future generations born in
14632-444: The water drains or evaporates, soil structure weakens and sometimes becomes viscous until it regains strength with decreasing moisture content. One visible sign of permafrost degradation is the random displacement of trees from their vertical orientation in permafrost areas. Global warming has been increasing permafrost slope disturbances and sediment supplies to fluvial systems, resulting in exceptional increases in river sediment. On
14756-473: The world were cut down. Deforestation and forest degradation continue to take place at alarming rates, which contributes significantly to the ongoing loss of biodiversity . Deforestation is more extreme in tropical and subtropical forests in emerging economies. More than half of all plant and land animal species in the world live in tropical forests . As a result of deforestation, only 6.2 million square kilometres (2.4 million square miles) remain of
14880-564: The world, especially in East Asian countries, reforestation and afforestation are increasing the area of forested lands. The amount of forest has increased in 22 of the world's 50 most forested nations. Asia as a whole gained 1 million hectares of forest between 2000 and 2005. Tropical forest in El Salvador expanded more than 20% between 1992 and 2001. Based on these trends, one study projects that global forestation will increase by 10%—an area
15004-469: The year 2022 concluded that if the goal of preventing 2 °C (3.6 °F) of warming was realized, then the average annual permafrost emissions throughout the 21st century would be equivalent to the year 2019 annual emissions of Russia. Under RCP4.5, a scenario considered close to the current trajectory and where the warming stays slightly below 3 °C (5.4 °F), annual permafrost emissions would be comparable to year 2019 emissions of Western Europe or
15128-456: Was 10 million hectares and the average annual forest area net loss in the 2000–2010 decade was 4.7 million hectares. The world has lost 178 million ha of forest since 1990, which is an area about the size of Libya. An analysis of global deforestation patterns in 2021 showed that patterns of trade, production, and consumption drive deforestation rates in complex ways. While the location of deforestation can be mapped, it does not always match where
15252-461: Was also greatest in the tropics and subtropics but is occurring in every climatic domain (except in the temperate) as populations increase. An estimated 420 million ha of forest has been lost worldwide through deforestation since 1990, but the rate of forest loss has declined substantially. In the most recent five-year period (2015–2020), the annual rate of deforestation was estimated at 10 million ha, down from 12 million ha in 2010–2015. Africa had
15376-519: Was built up over thousands of years. This amount equals almost half of all organic material in all soils , and it is about twice the carbon content of the atmosphere , or around four times larger than the human emissions of carbon between the start of the Industrial Revolution and 2011. Further, most of this carbon (~1,035 billion tons) is stored in what is defined as the near-surface permafrost, no deeper than 3 metres (9.8 ft) below
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