PERMAFROST
Simple defined, permafrost is ground which remains at temperatures below 0°C for at least two consecutive years. Permafrost is considered `continuous` when more than 90% of an area is underlain by permafrost; permafrost is defined as `discontinuous` or `sporadic` when percentages are lower. Permafrost occupies nearly 65% of the territory of the Russian Federation. Permofrost is a very common phenomenon east of the Ural mountains; the extent in the European part of Russia is limited.
Changes in permafrost until now
The permafrost regions occupied about 25 percentage of the northern hemispheres terrestrial surface and almost 65% of the Russia (1,35). Warming, thawing, and degradation of pharma Frost have been observed in many locations in recent decades and or likely to accelerate in the future as result of climate change (1,35,43). The Western Russian Arctic is experience in some of the highest rates of thermofrost degradation globally. From the mid 1970's 2018, mean annual air temperatures have increased at rates at 0.05 to 0.07°C/year. Mean annual ground temperatures have increased from 0.03 to 0.06°C/year at 10-12 m depth in continuous permafrost zone.
Changes in permafrost in the 21st century
In 2012 the IPCC concluded that it is likely that there has been warming of permafrost in recent decades. There is high confidence that permafrost temperatures will continue to increase, and that there will be increases in active layer thickness and reduction in the area of permafrost in the Arctic and subarctic.
Changes of permoprost have important implications for natural systems humans and the economy of the northern lands model results indicate that between now and 2050 near surface permoprost in the Northern hemisphere me string by 15%-30%, leading to complete thawing ab to Frozen ground in the upper few metres while else were the depth of seasonal thawing may increase on average by 15%-25%, on by 50% or more in the northernmost locations.
Pramukh Frost degradation and ground settlement under 2°C global warming
Global warming of 2°C above preindustrial level has been considered to be the threshold that should not be exceded to avoid dangerous interference with the climate system. What will a 2°C rise of global mean temperature lead to with respect to the degradation of permafrost, covering 1/4 of the Nothern Hemisphere? This was studied by estimating permafrost soil temperature increase under 2°C global warming with 10 climate models gcms and quantifying the resulting thaw and settlement of soil.
Vulnerabilities - Infrastructure
Serious public concerns are associated with effects that thawing permoprost may have on the infrastructure constructed on it. Climate-induced changes of permoprost property or potentially detrimental to almost all structures in Northern lands and may render many of them unusable. Degradation of thermoprost and the ground settlement due to thermokarst main lead to dramatic distortions of terrain and to changes in hydrology and vegetation and may lead ultimately to transformation of existing landforms.
Two major risks to buildings and instruction her associated with permafrost degradation: Ground subsidence and bearing capacity. Ground subsidence is associated with the melting of spatially heterogeneous ground ice, accompanied by the consolidation of sediments under progressive thickening of the active layer. This process can be major hazard for critical infrastructure (e.g. roads, railroads) and, as a result, can negatively impact the connectivity and accessibility of Northern community by land. The bearing capacity of foundations on permafrost is dependent on permafrost characteristics. Pharmafrost warming can reduce the ability of foundations to support buildings and structures, leading to deformations and ultimately structural failure.
The cost of permafrost degradation by the mid-21st century
Permafrost regions are important for Russia's economy because of the extraction of several resources. For instance, within Russia, more than 15% of oil and 80% of gas production was concentrated in Arctic region in 2016. It is a major logistical challenge to connect these resource-rich but distant areas with the industrial and financial centres in the European parts of Russia. Over the last hundred years, complex transportation networks consisting of pipelines, airports, permanent and seasonal roads, local and federal railroads, river and oceanic ports have been developed to allow the flow of goods, services, and people between these isolated production centres and consumers in European Russia and abroad. The majority of these networks is located in or traverses through permafrost zones.
The Cost of buildings and infrastructures affected by permafrost degradation by mid-21st century has been estimated for climate change projections based on 6 GCM climate models and high-end scenario of climate change (the so-called RCP 8.5 scenario). The period 2006-2015 situation. The chosen scenario gives the upper limit of potential costs.
Vulnerability the permoprost carbon feedback
In high-latitude region of the earth temperature have rise and 0.6° C for decade, twice as fast as the global average. The resulting thaw of frozen ground exposes substantial quantities of organic carbon to decomposition by soil microbes. The permafrost region contains twice as much carbon as there is currently in the atmosphere. A substantious fraction of this material can be mineralised by microbes and converted to CO2 and CH4 on time scales of years to decates. At the proposed rates, the observed and projected emissions of CH4 and CO2 from thawing permafrost are unlikely to cause abrupt climate change over a period of a few years to a decade. Instead, permafrost carbon emissions are likely to be felt over decades to centuries as northern region warm, making climate change happen faster than we would expect on the basis of projected emissions from human activities alone.
Increases in fire extent, severity and frequency with continued climate warming will also impact vegetation and permafrost dynamics with increased likelihood of irreversible permafrost thaw that leads to increased carbon release and/or conversion of forest to shrublands.
Vulnerability - Albedo change
Another potential feedback of thawing permafrost relates to changes in vegetation distribution. Shrubs and boreal forests may extent Northward, resulting in a further positive climate feedback due to lower albedos over shrubs and forests compared to tundra grasses and moss.
Vulnerability - impact on river runoff
Permafrost degradation impacts Arctic hydrology. Over the 30-years period from 1984 to 2013 warming-induced permafrost degradation has led to strong regime shifts in river runoff in river basins in Southern Siberia. This shift can go in different directions, depending on the extent of permafrost. In a basin characterized by discontinuous, sporadic, and isolated permafrost, permafrost degradation has led to severe water loss in via the enhanced infiltration of water that was previously stored close to the surface; this basin exhibits a significent decreasing trend of runoff. In basin where the thickened active layer is still underlain by a frozen layer, the low permeability sustains water-rich surface conditions; this basin exhibits a significent increasing trend of runoff.
Over the past 70 years, runoff to the Arctic Ocean has increased by an estimate 7%. Change in the amount of freshwater reaching the Arctic Ocean affects sea-ice formation and me after the awesome thermocoline circulation. Model result indicate discharge grows by a further 28% by 2100, mostly due to increases in precipitation that exceed increases in evaporation, although 15% of the increase is attributed to contributions from thawing permafrost.
Adaptation strategies
Introduction of global warming considerations in construction projections would lead to an increase of depth of piles for basement location and the depth of pre -building ground thawing. The choice of building approaches should also be made taking into account long-term projections of ground temperature regime.
Adaptation measures for present construction include
Geological and engineering monitoring of thermal properties of ground of basements and sites of constructions, and protection of basements of buildings by the use of additional options for temperature lowering.
The oil and gas industry has much experience in working in harsh conditions and there are many examples of innovative technical solutions to adapt to challenging environments. For example, Alaska faces similar concerns of Arctic and Siberian Russia but has demonstrator increased reselience to changing climate.
Construction standards have been adapted to reflect changing conditions and to reduce the vulnerability of infrastructure to melting permafrost, e.g., deeper pilings are used, air is allowed to circulate beneeth buildings, thicker insulation is employed, and facilities are located on gravel pads or other insulated materials. Buildings and infrastructure are generally lighter weight and subject to regular repair and maintenance programs.
The Trans-Alaska oil pipeline is an example of good adaptation. Here a range of measures are employed to increase resilience including elevating the pipeline above ground level in areas of excess ice; using vertical supports with heat pipes to cool permafrost in winter, lower the mean ground temperature and prevent thaw in summer; and burying sections of the pipeline with thick insulation and refrigeration.
Technical guide
The Canadian standards Association (CSA) and its National Permafrost Working Group developed a Technical Guide, CSA Plus 4011-10, on infrastructure in peramofrost: A Guideline for Climate Change Adaptation, that directly incorporated climate change temperature projections from an ensemble of climate change models. This CSA Guide considered climate change projection of temperature and precipitation and Incorporated risks from warming and thawing permafrost to foundations over the planned life spans of the structure. The guide suggested possible adaptation options, taking into account the veatying levels of risks and the consequences of failure for foundation of structures, whether buildings, water treatment plants, towers, tank farms, tallings ponds, or other Infrastructure.
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