In geology, permafrost is ground, including rock or (cryotic) soil, at or below the freezing point of water 0 °C (32 °F) for two or more years. Most permafrost is located in high latitudes (in and around the Arctic and Antarctic regions), but at lower latitudes alpine permafrost occurs at higher elevations. Ground ice is not always present, as may be in the case of non-porous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material. Permafrost accounts for 0.022% of total water on Earth and the permafrost region covers 24% of exposed land in the Northern Hemisphere. It also occurs subsea on the continental shelves of the continents surrounding the Arctic Ocean, portions of which were exposed during the last glacial period.
The thawing of permafrost has implications for the global climate. A global temperature rise of 1.5 °C (2.7 °F) above current levels would be enough to start the thawing of permafrost in Siberia, according to one group of scientists.
Map showing extent and types of permafrost in the Northern Hemisphere
|Used in||International Permafrost Association|
|Climate||High latitudes, alpine regions|
"In contrast to the relative dearth of reports on frozen ground in north America prior to World War II, a vast literature on the engineering aspects of permafrost was available in Russian. Beginning in 1942, Siemon William Muller delved into the relevant Russian literature held by the Library of Congress and the U.S. Geological Survey Library so that he was able to furnish the government an engineering field guide and a technical report about permafrost by 1943", year in which he coined the term as a contraction of permamently frozen ground. Although originally classified (as U.S. Army. Office of the Chief of Engineers, Strategic Engineering Study, no. 62, 1943), in 1947 a revised report was released publicly, which is regarded as the first North American treatise on the subject.
Permafrost is soil, rock or sediment that is frozen for more than two consecutive years. In areas not overlain by ice, it exists beneath a layer of soil, rock or sediment, which freezes and thaws annually and is called the "active layer". In practice, this means that permafrost occurs at an mean annual temperature of −2 °C (28.4 °F) or colder. Active layer thickness varies with the season, but is 0.3 to 4 meters thick (shallow along the Arctic coast; deep in southern Siberia and the Qinghai-Tibetan Plateau). The extent of permafrost varies with the climate: in the Northern Hemisphere today, 24% of the ice-free land area, equivalent to 19 million square kilometers, is more or less influenced by permafrost. Of this area slightly more than half is underlain by continuous permafrost, around 20 percent by discontinuous permafrost, and a little less than 30 percent by sporadic permafrost. Most of this area is found in Siberia, northern Canada, Alaska and Greenland. Beneath the active layer annual temperature swings of permafrost become smaller with depth. The deepest depth of permafrost occurs where geothermal heat maintains a temperature above freezing. Above that bottom limit there may be permafrost, whose temperature doesn't change annually—"isothermal permafrost".
Permafrost typically forms in any climate where the mean annual air temperature is less than the freezing point of water. Exceptions are found in moist-wintered forest climates, 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 be exceptions. Since all glaciers are warmed at their base by geothermal heat, temperate glaciers, which are near 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.
Typically, the below-ground temperature varies less from season to season than the air temperature, with mean annual temperatures tending to increase with depth as a result of 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 northerly aspect—creating discontinuous permafrost. Usually, permafrost will remain discontinuous in 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 be even 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 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.
|Qinghai-Tibet Plateau||1,300 km2 (500 sq mi)|
|Khangai-Altai Mountains||1,000 km2 (390 sq mi)|
|Brooks Range||263 km2 (102 sq mi)|
|Siberian Mountains||255 km2 (98 sq mi)|
|Greenland||251 km2 (97 sq mi)|
|Ural Mountains||125 km2 (48 sq mi)|
|Andes||100 km2 (39 sq mi)|
|Rocky Mountains (US and Canada)||100 km2 (39 sq mi)|
|Fennoscandian mountains||75 km2 (29 sq mi)|
|Remaining||<100 km2 (39 sq mi)|
At mean annual soil surface temperatures below −5 °C (23 °F) 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 southerly 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 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.
Estimates of the total area of alpine permafrost vary. Bockheim and Munroe combined three sources and made the tabulated estimates by region, totaling 3,560,000 km2 (1,370,000 sq mi).
Alpine permafrost in the Andes has not been mapped. Its extent has been modeled to assess the amount of water bound up in these areas. In 2009, a researcher from Alaska found permafrost at the 4,700 m (15,400 ft) level on Africa's highest peak, Mount Kilimanjaro, approximately 3° north of the equator.
Subsea permafrost occurs beneath the seabed and exists in 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, the permafrost became submerged shelves under relatively warm and salty boundary conditions, compared to surface permafrost. Therefore, subsea permafrost exists in conditions that lead to its diminishment. According to Osterkamp, subsea permafrost is a factor in 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." It also contains gas hydrates in places, which are both a "potential abundant source of energy", but also may destabilize, as subsea permafrost warms and thaws, producing large amounts of methane gas, which is a potent green-house gas.
|Time (yr)||Permafrost depth|
|1||4.44 m (14.6 ft)|
|350||79.9 m (262 ft)|
|3,500||219.3 m (719 ft)|
|35,000||461.4 m (1,514 ft)|
|100,000||567.8 m (1,863 ft)|
|225,000||626.5 m (2,055 ft)|
|775,000||687.7 m (2,256 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. The base depth of permafrost reaches 1,493 m (4,898 ft) in the northern Lena and Yana River basins in Siberia. The geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior. Away from tectonic plate boundaries, it is about 25–30 °C/km (72–87 °F/mi) near the surface in most of the world. It varies with the thermal conductivity of geologic material and is less for permafrost in soil than in bedrock.
Calculations indicate that the time required to form the deep permafrost underlying Prudhoe Bay, Alaska was over a half-million years. This extended over several glacial and interglacial cycles of the Pleistocene and suggests that the present climate of Prudhoe Bay is probably considerably warmer than it has been on average over that period. Such warming over the past 15,000 years is widely accepted. The table to the right shows that the first hundred metres of permafrost forms relatively quickly but that deeper levels take progressively longer.
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 a minimum thickness of at least 2 m and a short diameter of at least 10 m. First recorded North American observations 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 Kh. P. Laptev, respectively. Two categories of massive ground ice are buried surface ice and intrasedimental ice (also called constitutional ice).
Intrasedimental ice forms by in-place freezing of subterranean waters and is dominated by segregational ice which results from the crystallizational differentiation taking place during the freezing of wet sediments, accompanied by water migrating to the freezing front.
Additionally, ice wedges—a separate type of ground ice—produce recognizable patterned ground or tundra polygons. Ice wedges form in a pre-existing geological substrate and were first described in 1919.
Permafrost processes manifest themselves in large-scale land forms, such as palsas and pingos and smaller-scale phenomena, such as patterned ground found in arctic, periglacial and alpine areas.
The permafrost carbon cycle (Arctic Carbon Cycle) deals with 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 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.
Arctic permafrost has been diminishing for many centuries. The consequence is thawing soil, which may be weaker, and release of methane, which contributes to an increased rate of global warming as part of a feedback loop.
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 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 is related to the tundra. Alpine permafrost also occurred in the Drakensberg during glacial maxima above about 3,000 metres (9,840 ft).
The ground can consist of many substrate materials, including bedrock, sediment, organic matter, water or ice. Frozen ground is that which is below the freezing point of water, whether or not water is present in the substrate. Ground ice is not always present, as may be the case with nonporous bedrock, but it frequently occurs and may be present in amounts exceeding the potential hydraulic saturation of the thawed substrate.
By definition, permafrost is ground that remains frozen for two or more years. Since frozen soil, including permafrost, comprises a large percentage of substrate materials other than ice, it thaws rather than melts even as any ice content melts. An analogy is when a freezer door is left open, although the ice in the freezer may change phase to a liquid, the food solids will not experience a phase change. In aggregate, the food thaws but does not melt. Melting implies the phase change of all solids to liquid. One visible sign of permafrost degradation is the random displacement of trees from their vertical orientation in permafrost areas.
As a consequence, precipitation has increased which in turn results in the weakening and eventual collapse of buildings in areas such as Norilsk in northern Russia, which lies upon the permafrost.
Over the past century, an increasing number of alpine rock slope failure events in mountain ranges around the world have been recorded. It is expected that the high number of structural failures is due to permafrost thawing, which is thought to be linked to climate change. Permafrost thawing is thought to have contributed to the 1987 Val Pola landslide that killed 22 people in the Italian Alps. In mountain ranges, much of the structural stability can be attributed to glaciers and permafrost. As climate warms, permafrost thaws, which results in a less stable mountain structure, and ultimately more slope failures. Increasing temperatures allow deeper active layer depths, resulting in increased water infiltration. Ice within the soil melts, causing loss of soil strength, accelerated movement, and potential debris flows.
McSaveney reported massive rock and ice falls (up to 11.8 million m3), earthquakes (up to 3.9 Richter), floods (up to 7.8 million m3 water), and rapid rock-ice flow to long distances (up to 7.5 km at 60 m/s) caused by “instability of slopes” in high mountain permafrost. Instability of slopes in permafrost at elevated temperatures near freezing point in warming permafrost is related to effective stress and buildup of pore-water pressure in these soils. Kia and his co-inventors invented a new filter-less rigid piezometer (FRP) for measuring pore-water pressure in partially frozen soils such as warming permafrost soils. They extended the use of effective stress concept to partially frozen soils for use in slope stability analysis of warming permafrost slopes. The use of effective stress concept has many advantages such as ability to extend the concepts of "Critical State Soil Mechanics" into frozen ground engineering.
In the northern circumpolar region, permafrost contains 1700 billion tons of organic material equaling almost half of all organic material in all soils. This pool was built up over thousands of years and is only slowly degraded under the cold conditions in the Arctic. The amount of carbon sequestered in permafrost is four times the carbon that has been released to the atmosphere due to human activities in modern time. One manifestation of this is yedoma, which is an organic-rich (about 2% carbon by mass) Pleistocene-age loess permafrost with ice content of 50–90% by volume.
Formation of permafrost has significant consequences for ecological systems, primarily due to constraints imposed upon rooting zones, but also due to limitations on den and burrow geometries for fauna requiring subsurface homes. Secondary effects impact species dependent on plants and animals whose habitat is constrained by the permafrost. One of the most widespread examples is the dominance of Black Spruce in extensive permafrost areas, since this species can tolerate rooting pattern constrained to the near surface.
One gram of soil from the active layer may include more than one billion bacteria cells. If placed along each other, bacteria from one kilogram of active layer soil will form a 1000 km long chain. The number of bacteria in permafrost soil varies widely, typically from 1 to 1000 million per gram of soil. Most of these bacteria and fungi in permafrost soil can not be cultured in the laboratory, but the identity of the microorganisms can be revealed by DNA-based techniques.
The Arctic region is one of the many natural sources of the greenhouse gas methane. Global warming accelerates its release, due to both release of methane from existing stores, and from methanogenesis in rotting biomass. Large quantities of methane are stored in the Arctic in natural gas deposits, permafrost, and as submarine clathrates. Permafrost and clathrates degrade on warming, thus large releases of methane from these sources may arise as a result of global warming. Other sources of methane include submarine taliks, river transport, ice complex retreat, submarine permafrost and decaying gas hydrate deposits. Preliminary computer analyses suggest that permafrost could produce carbon equal to 15 percent or so of today’s emissions from human activities.
A hypothesis forwarded by Sergey Zimov is that the reduction of herds of large herbivores has increased the ratio of energy emission and energy absorption tundra (energy balance) in a manner that increases the tendency for net thawing of permafrost. He is testing this hypothesis in an experiment at Pleistocene Park, a nature reserve in northeastern Siberia.
According to IPCC Fifth Assessment Report there is high confidence that permafrost temperatures have increased in most regions since the early 1980s. Observed warming was up to 3 °C in parts of Northern Alaska (early 1980s to mid-2000s) and up to 2 °C in parts of the Russian European North (1971–2010). 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. It is thought that permafrost thawing could exacerbate global warming by releasing methane and other hydrocarbons, which are powerful greenhouse gases. It also could encourage erosion because permafrost lends stability to barren Arctic slopes.
Arctic temperatures are expected to increase at roughly twice the global rate. The Intergovernmental Panel on Climate Change (IPCC) will in their fifth report establish scenarios for the future, where the temperature in the Arctic will rise between 1.5 and 2.5 °C by 2040 and with 2 to 7.5 °C by 2100. Estimates vary on how many tons of greenhouse gases are emitted from thawed permafrost soils. One estimate suggests that 110–231 billion tons of CO2 equivalents (about half from carbon dioxide and the other half from methane) will be emitted by 2040, and 850–1400 billion tons by 2100. This corresponds to an average annual emission rate of 4–8 billion tons of CO2 equivalents in the period 2011–2040 and annually 10–16 billion tons of CO2 equivalents in the period 2011–2100 as a result of thawing permafrost. For comparison, the anthropogenic emission of all greenhouse gases in 2010 is approximately 48 billion tons of CO2 equivalents. Release of greenhouse gases from thawed permafrost to the atmosphere may increase global warming.
The International Permafrost Association (IPA) is an integrator of issues regarding permafrost. It convenes International Permafrost Conferences, undertakes special projects such as preparing databases, maps, bibliographies, and glossaries, and coordinates international field programmes and networks. Among other issues addressed by the IPA are: Problems for construction on permafrost owing to the change of soil properties of the ground on which structures are placed and the biological processes in permafrost, e.g. the preservation of organisms frozen in situ.
Building on permafrost is difficult because the heat of the building (or pipeline) can thaw the permafrost and destabilize the structure. Three common solutions include: using foundations on wood piles; building on a thick gravel pad (usually 1–2 metres/3.3–6.6 feet thick); or using anhydrous ammonia heat pipes. The Trans-Alaska Pipeline System uses heat pipes built into vertical supports to prevent 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".
The Permafrost Research Institute in Yakutsk, found that the sinking of large buildings into the ground can be prevented by using pile foundations extending down to 15 metres (49 ft) or more. At this depth the temperature does not change with the seasons, remaining at about −5 °C (23 °F).
In 2012, Russian researchers proved that permafrost can serve as a natural repository for ancient life forms by reviving of Silene stenophylla from 30,000 year old tissue found in an Ice Age squirrel burrow in the Siberian permafrost. This is the oldest plant tissue ever revived. The plant was fertile, producing white flowers and viable seeds. The study demonstrated that tissue can survive ice preservation for tens of thousands of years. A 2016 outbreak of anthrax in the Yamal Peninsula is believed to be due to thawing permafrost.
Here and there, roadside utility poles destabilized by the melting tilt at crazy angles. So do trees, creating a phenomenon known as drunken forest.
…caused what the locals call "drunken forests," the trees tilting and leaning…
Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in negative effects, as methane is itself a powerful greenhouse gas.
The Arctic region is one of the many natural sources of the greenhouse gas methane. Global warming accelerates its release, due to both release of methane from existing stores, and from methanogenesis in rotting biomass. Large quantities of methane are stored in the Arctic in natural gas deposits, permafrost, and as undersea clathrates. Permafrost and clathrates degrade on warming, thus large releases of methane from these sources may arise as a result of global warming. Other sources of methane include submarine taliks, river transport, ice complex retreat, submarine permafrost and decaying gas hydrate deposits.Concentrations in the Arctic atmosphere are higher by 8–10% than that in the Antarctic atmosphere. During cold glacier epochs, this gradient decreases to practically insignificant levels. Land ecosystems are considered the main sources of this asymmetry, although it has been suggested that "the role of the Arctic Ocean is significantly underestimated." Soil temperature and moisture levels have been found to be significant variables in soil methane fluxes in tundra environments.Climate change feedback
Climate change feedback is important in the understanding of global warming because feedback processes may amplify or diminish the effect of each climate forcing, and so play an important part in determining the climate sensitivity and future climate state. Feedback in general is the process in which changing one quantity changes a second quantity, and the change in the second quantity in turn changes the first. Positive feedback amplifies the change in the first quantity while negative feedback reduces it.The term "forcing" means a change which may "push" the climate system in the direction of warming or cooling. An example of a climate forcing is increased atmospheric concentrations of greenhouse gases. By definition, forcings are external to the climate system while feedbacks are internal; in essence, feedbacks represent the internal processes of the system. Some feedbacks may act in relative isolation to the rest of the climate system; others may be tightly coupled; hence it may be difficult to tell just how much a particular process contributes.Forcings and feedbacks together determine how much and how fast the climate changes. The main positive feedback in global warming is the tendency of warming to increase the amount of water vapor in the atmosphere, which in turn leads to further warming. The main negative feedback comes from the Stefan–Boltzmann law, the amount of heat radiated from the Earth into space changes with the fourth power of the temperature of Earth's surface and atmosphere. Observations and modelling studies indicate that there is a net positive feedback to warming. Large positive feedbacks can lead to effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change."Climate change in Russia
Global warming in Russia describes the global warming related issues in Russia. This includes climate politics, contribution to global warming and the influence of global warming in Russia. In 2009 Russia was ready to reduce emissions 20–25% from its 1990 emission levels by the year 2020.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. Related impacts include ocean circulation changes, increased input of freshwater, and ocean acidification. Indirect effects through potential climate teleconnections to mid latitudes may result in a greater frequency of extreme weather events (flooding, fires and drought), ecological, biological and phenology changes, biological migrations and extinctions, 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. Presently, the Arctic is warming twice as fast compared to the rest of the world. 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. According to a study published in 2016, about 0.5 °C of the warming in the Arctic has been attributed to reductions in sulfate aerosols in Europe since 1980.Cryosphere
The cryosphere (from the Greek κρύος kryos, "cold", "frost" or "ice" and σφαῖρα sphaira, "globe, ball") is those portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground (which includes permafrost). Thus, there is a wide overlap with the hydrosphere. The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in the global climate and in climate model response to global changes. The term deglaciation describes the retreat of cryospheric features. Cryology is the study of cryospheres.Drunken trees
Drunken trees, tilted trees, or a drunken forest, is a stand of trees displaced from their normal vertical alignment.This most commonly occurs in northern subarctic taiga forests of black spruce (Picea mariana) under which discontinuous permafrost or ice wedges have melted, causing trees to tilt at various angles.
Tilted trees may also be caused by frost heaving, and subsequent palsa development, hummocks, earthflows, forested active rock glaciers,landslides, or earthquakes. In stands of spruce trees of equal age that germinated in the permafrost active layer after a fire, tilting begins when the trees are 50 to 100 years old, suggesting that surface heaving from new permafrost aggradation can also create drunken forests.Gelisol
Gelisols are an order in USDA soil taxonomy. They are soils of very cold climates which are defined as containing permafrost within two meters of the soil surface. The word "Gelisol" comes from the Latin gelare meaning "to freeze", a reference to the process of cryoturbation that occurs from the alternating thawing and freezing characteristic of Gelisols.
In the World Reference Base for Soil Resources (WRB), Gelisols are known as Cryosols. In soil taxonomy, Gelisols key out before the Histosols. In the WRB, the Histosols key out before the Cryosols. Organic permafrost soils are therefore Gelisols (Histels) in the soil taxonomy and Histosols (Cryic Histosols) in the WRB.
Structurally, Gelisols may have a B horizon and more commonly have an A horizon and/or O horizon resting on the permafrost. Because soil organic matter accumulates in the upper layer, most Gelisols are black or dark brown in soil color, followed by a shallow mineral layer. Despite the influence of glaciation in most areas where Gelisols occur, chemically they are not highly fertile because nutrients, especially calcium and potassium, are very easily leached above the permafrost. The permafrost greatly restricts the engineering use of Gelisols, as large structures (e.g. buildings) subside as the frozen earth thaws when they are put in place.
Gelisols are found chiefly in Siberia, Alaska and Canada. Smaller areas are found in the Andes (mainly near the intersection between Chile, Bolivia and Argentina), Tibet, northern Scandinavia and the ice-free parts of Greenland and Antarctica. Fossil Gelisols are known from as far back as Precambrian ice ages 900 million years ago.Mount Wilson (Colorado)
Mount Wilson is the highest summit of the San Miguel Mountains range of the Rocky Mountains of North America. The prominent 14,252-foot (4,344 m) fourteener is located in the Lizard Head Wilderness of San Juan National Forest, 10.6 miles (17.1 km) north by east (bearing 12°) of the Town of Rico in Dolores County, Colorado, United States. Mount Wilson should not to be confused with the lower Wilson Peak nearby.
The peak was named for A.D. Wilson, a topographer with the Hayden Survey. He was in the first ascent party, which climbed the peak on September 13, 1874, via the south ridge (a difficult route, not often climbed today).Palsa
A palsa is a low, often oval, frost heave occurring in polar and subpolar climates, which contain permanently frozen ice lenses. Like pingos, palsas consist of an ice core with overlying soil, but they are generally smaller than pingos, often occur in groups and may develop from ground water without additional hydrostatic pressure. Palsas are characteristically found in areas with discontinuous permafrost, and in such areas they may be the only reliable surface evidence of permafrost. Surface water, found in bogs, enhances palsa formation in areas called palsa bogs.Peel River (Canada)
The Peel River (Teetl'it Gwinjik in Gwich’in) is a tributary of the Mackenzie River in the Yukon and Northwest Territories in Canada. Its source is in the Ogilvie Mountains in the central Yukon at the confluence of the Ogilvie River and Blackstone River. Its main tributaries are:
Wind River (Yukon)
Bonnet Plume River
Snake River (Yukon)The Peel River joins the Mackenzie in the Mackenzie Delta. However, a distributary of the Peel is the headwater for a channel that later collects distributaries of the Mackenzie. This means that a channel can be followed for a longer distance downriver until it, itself, disseminates into the shared delta. This arguably adds a greater length to the Peel River.
The Dempster Highway crosses it at Fort McPherson, via a ferry during the summer months and an ice bridge during the winter. The Peel River is a wilderness river and Fort McPherson is the only community along its banks. The Yukon part of the Peel Watershed is undergoing land use planning.
Steven Kokelj, a specialist in permafrost, has documented significant changes in the balance of dissolved ions in the river's water as the region's permafrost starts to melt.
Ions of elements like calcium and sulphur dissolve easily when the permafrost thaws.Periglaciation
Periglaciation (adjective: "periglacial," also referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and other structures. "Periglacial" suggests an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner.Tundra is a common ecological community in periglacial areas.Permafrost (story)
"Permafrost" is a science fiction novelette by American writer Roger Zelazny, published in 1986.Pithovirus
Pithovirus, first described in a 2014 paper, is a genus of giant virus known from one species, Pithovirus sibericum, which infects amoebas. It is a double-stranded DNA virus, and is a member of the nucleocytoplasmic large DNA viruses clade. The 2014 discovery was made when a viable specimen was found in a 30,000-year-old ice core harvested from permafrost in Siberia, Russia.Syngenetic permafrost growth
Syngenetic permafrost growth is a mode of the growth of permafrost whereby additional material is deposited to a permafrost site during freezing conditions, causing the permafrost layer to build upwards. It is cited as an efficient mode of permafrost growth, compared with heterogenetic permafrost growth, which occurs when freezing temperatures penetrate into previously unfrozen ground of uniform composition. Lunardini gives the basic formulas for permafrost generation under both modes.Syngenetic deposition of frozen materials comes from any of a variety of sources, sediment from streams and rivers, material fallen from hillsides, material blown by the wind, and material deposited at the bottom of lakes. Studies of such formations are partly based on observations in the Cold Regions Research and Engineering Laboratory tunnel into permafrost near Fairbanks, Alaska.Ice wedges that intrude into cracks in permafrost may be regarded as syngenetic, if they grow upwards.Talik
A talik is a layer of year-round unfrozen ground that lies in permafrost areas. In regions of continuous permafrost, taliks often occur underneath shallow thermokarst lakes and rivers, where the deep water does not freeze in winter, and thus the soil underneath will not freeze either. Sometimes closed, open and through talik are distinguished. These terms refer to whether the talik is completely surrounded by permafrost, is open to the top (e.g. a thermokarst lake), or open to both top and unfrozen layers beneath the permafrost, respectively.Terrain softening
The landscape polewards of around 30 degrees latitude on Mars has a distinctively different appearance to that nearer the equator, and is said to have undergone terrain softening. Softened terrain lacks the sharp ridge crests seen near the equator, and is instead smoothly rounded. This rounding is thought to be caused by high concentrations of water ice in soils. The term was coined in 1986 by Steve Squyres and Michael Carr from examining imagery from the Viking missions to Mars.
Below 30 degrees of latitude, impact craters have steep walls; well-defined, sharp rims; and flat or smoothly bowl-shaped floors. Ridges on intercrater plains come to similarly well-defined, pointed crests. However, above this latitude, these same features appear very different. The crests seen on ridges and crater rims appear strongly rounded and much more poorly defined. The relief (height) of features is somewhat reduced. Small craters are noticeably less common. In other words, terrain which elsewhere looked sharp here looks "soft". This texture has also been described as "smooth", or "rolling". Softened craters are also commonly infilled with concentric patterns on their floors.On Earth, diffusive creep of soils is associated with rounded hillslopes. Squyres and Carr thus attributed the softened texture to accelerated viscous creep in shallow soils near the surface, and went on to associate this accelerated creep with the presence of ground ice at these latitudes. This conclusion has been largely borne out by subsequent research. In the late 1980s some attempts were made to link terrain softening with dust and aeolian processes, though this hypothesis has largely been superseded by more recent observations.Terrain softening is one of a suite of features seen in the midlatitudes of Mars—also including lobate debris aprons, lineated valley fill, concentric crater fill, latitude dependent mantle, patterned ground, viscous flow features, arcuate ridges, recurring slope lineae, and gullies—whose form and distribution strongly suggest the abundance of ice at the surface.Thermokarst
Thermokarst is a land surface characterised by very irregular surfaces of marshy hollows and small hummocks formed as ice-rich permafrost thaws, that occurs in Arctic areas, and on a smaller scale in mountainous areas such as the Himalayas and the Swiss Alps. These pitted surfaces resemble those formed by solution in some karst areas of limestone, which is how they came to have karst attached to their name without the presence of any limestone. Small domes that form on the surface due to frost heaving with the onset of winter are only temporary features. They then collapse with the arrival of next summer's thaw and leave a small surface depression. Some ice lenses grow and form larger surface hummocks, which last many years and sometimes become covered with grasses and sedges, until they begin to thaw. These domed surfaces eventually collapse either annually or after longer periods and form depressions which contribute to uneven surfaces. These are included within the general label of thermokarst.
The formation of permafrost thaw lakes due to warming climate is a positive feedback loop, as methane and carbon dioxide are released as permafrost thaws, contributing to further climate warming.
The Batagaika crater in Siberia is an example of a large thermokarst depression.Tundra
In physical geography, tundra () is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра (tûndra) from the Kildin Sami word тӯндар (tūndâr) meaning "uplands", "treeless mountain tract". Tundra vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline.
There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.Yedoma
Yedoma is an organic-rich (about 2% carbon by mass) Pleistocene-age permafrost with ice content of 50–90% by volume. The amount of carbon trapped in this type of permafrost is much more prevalent than originally thought and may be about 210 to 450 Gt, that is a multiple of the amount of carbon released into the air each year by the burning of fossil fuels. Thawing yedoma is a significant source of atmospheric methane (about 4 Tg of CH4 per year).
The Yedoma region currently occupies an area of more than one million square kilometers from northeast Siberia to Alaska and Canada, and in many regions is tens of meters thick. During the Last Glacial Maximum, when the global sea level was 120 m lower than that of today, similar deposits covered substantial areas of the exposed northeast Eurasian
continental shelves. At the end of last ice age, at the Pleistocene — Holocene transition, thawing yedoma and the resulting thermokarst lakes may have produced 33 to 87% of the high-latitude increase in atmospheric methane concentration.
|Soils and deposits|
|Biomes and ecotones|