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article imageThe Big Thaw: Permafrost thaw to cause significant Global Warming

By Robert Myles     Nov 29, 2012 in Environment
Thawing of permafrost is expected to cause significant additional global warming, not yet accounted for in climate predictions, warn scientists attached to the United Nations Environment Programme (UNEP) in a report released this week..
The UNEP analysis says government policymakers and climate scientists must take steps to monitor and prepare for significantly larger carbon dioxide and methane emissions into the Earth’s atmosphere caused as a result of the thawing of permafrost.
Permafrost (or cryotic soil as it is sometimes known) is soil which remains at or below the freezing point of water 0 °C (32 °F) for two or more years. Most permafrost is located in high latitudes, close to the North and South poles, but alpine permafrost may exist at high altitudes at much lower latitudes, an example being the Himalayas.
Extent of permafrost in Northern Hemisphere
Extent of permafrost in Northern Hemisphere
United Nations Environment Programme
Permafrost covers almost 25% of land masses in the northern hemisphere and is estimated to contain 1,700 gigatonnes of carbon dioxide. (One gigatonne is equal to a thousand million tonnes). The carbon dioxide (CO2) locked up in permafrost is estimated to equate to twice the amount of CO2 in the atmosphere. There are also significant deposits of methane (CH4) locked up in permanently frozen organic material within the permafrost. Methane is a greenhouse gas reckoned to be 20 times more efficient than CO2 at trapping the sun’s heat in the Earth’s atmosphere, according to the United States Environmental Protection Agency.
Currently, most of the Earth’s permafrost was formed either during or since the last ice age. In parts of Siberia and Northern Canada, the depth of permafrost has been measured in excess of 700 metres (2300 feet) below the surface. At the surface, there is an active layer of permafrost up to 2 metres deep. This active layer is neutral so far as methane and carbon dioxide emissions are concerned since it thaws in summer and re-freezes in winter. The worry is, however, that if existing global warming, whether anthropogenic (man-made) or natural, causes the active layer of permafrost to increase in thickness, then huge quantities of organic matter currently locked in the frozen soil would begin to thaw and decay, releasing large amounts of CO₂ and methane into the atmosphere. The release of further substantial amounts of greenhouse gases would, in turn, cause further thawing of the permafrost producing, in effect, a runaway thaw of these vast organic deposits, known as carbon feedback.
The UNEP report entitled Policy Implications of Warming Permafrost highlights potential hazards arising from carbon dioxide and methane released due to warming permafrost, hazards which have not so far been included in climate change modelling.
The report recommends that the Intergovernmental Panel on Climate Change (IPCC) carry out a special assessment of permafrost which would include the creation of national monitoring networks in countries with significant permafrost regions such as Russia, Canada, the United States, Greenland and China. UNEP also call for plans to be put in place to deal with the potential impact of permafrost thaw which is likely to affect coastal areas currently frozen as well as buildings, structures and industrial installations constructed in areas currently permanently frozen.
"Permafrost is one of the keys to the planet's future because it contains large stores of frozen organic matter that, if thawed and released into the atmosphere, would amplify current global warming and propel us to a warmer world. Its potential impact on the climate, ecosystems and infrastructure has been neglected for too long," said UN Under-Secretary General and UNEP Executive Director Achim Steiner.
"This report seeks to communicate to climate-treaty negotiators, policy makers and the general public the implications of continuing to ignore the challenges of warming permafrost," he added.
If carbon feedback were to take hold, accelerating permafrost thaw, it is unlikely the process could be reversed within human timescales. On current projections, arctic and alpine air temperatures are expected to increase at roughly twice the global rate. Climate projections are forecasting a substantial loss of permafrost by 2100. If global temperatures increase by 3°C on average, that would translate into a 6°C increase in the Arctic. The increased Arctic temperatures could result in a loss of anywhere between 30 to 85 per cent of near-surface permafrost, with all the repercussions that has for increased atmospheric carbon dioxide and methane levels.
Given that governments around the world have barely made a start on turning down the gas when it comes to carbon emissions, with some growth economies like India and China seemingly destined to add to atmospheric CO2, the report’s projections make for gloomy reading.
Warming permafrost could release between 43 to 135 gigatonnes of carbon dioxide equivalent by 2100 and between 246 to 415 gigatonnes by 2200. Permafrost emissions of greenhouse gases could start within the next few decades. Once the process was underway, the likelihood is that it would continue for several centuries.
Alarmingly, permafrost emissions could ultimately account for up to 39 per cent of total emissions. The report's lead author warned that this additional CO2 burden would have to be taken into account in any successor treaty to the Kyoto Protocol designed to address global climate change. Said lead author Kevin Schaefer, from the University of Colorado's National Snow and Ice Data Center,
“The release of carbon dioxide and methane from warming permafrost is irreversible: once the organic matter thaws and decays away, there is no way to put it back into the permafrost. Anthropogenic emissions' targets in the climate change treaty need to account for these emissions or we risk overshooting the 2°C maximum warming target."
Most recent climate projections tend to underestimate global temperature rises because the models do not take account of permafrost carbon feedback, the report says. As a consequence, targets for anthropogenic greenhouse gas emissions based on these climate projections would tend to undershoot the reductions truly required to make any impact on climate change.
The threat to infrastructure and ecosystems from permafrost thaw
Coastal erosion of permafrost resulted in the complete destruction of this house in Shishmaref  Alas...
Coastal erosion of permafrost resulted in the complete destruction of this house in Shishmaref, Alaska.
United Nations Environment Programme
Apart from the impact on levels of greenhouse gases in the atmosphere, any significant thaw in the permafrost would have a number of consequences some with the potential to affect populations thousands of miles from Arctic tundra regions:
• The principal ecosystems in permafrost regions are boreal forests to the southern extent and tundra in the north. Liquid water cannot permeate permafrost, so rain and melt water pool on the surface - forming countless lakes and wetlands used by migratory birds as summer breeding grounds. Changes in the ecosystem due to permafrost degradation would alter species composition, and with it animal habitat and migration.
• Longer growing seasons due to higher temperatures would encourage shrubs and woody vegetation resulting in a northward migration of the tree line. Permafrost degradation and the consequent drying of the land could also increase the frequency of bush and forest fires. Fire in boreal forests has recently increased in intensity and frequency, and could become more common in tundra regions.
• Thawing permafrost is structurally weak. As a result, buildings, roads, pipelines, railways and power lines constructed on ‘rock solid’ permafrost, may suffer settlement damage through ground subsidence. Infrastructure failure has already had dramatic environmental consequences, like the 1994 breakdown of the pipeline to the Vozei oilfield in Northern Russia, which resulted in a spill of 160,000 tonnes of oil, the world's largest terrestrial oil spill.
• Coastal settlements in permafrost regions are particularly vulnerable. There, the salt content of the frozen ground means relatively small temperature changes can turn ice to ground water.
• In the US state of Alaska alone, existing estimates for climate change could add up to US$6.1 billion to future costs for public infrastructure between now and 2030. There are few studies which evaluate the economic effects of permafrost degradation. The only certainty is that the costs of infrastructure maintenance and repair costs will be much higher once permafrost thaw is brought into the equation.
The full report Policy Implications of Warming Permafrost is available here on the United Nations Environment Programme website.
More about Permafrost, Greenhouse gases, Greenhouse gas emissions, CO2 Emissions, Methane greenhouse gas
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