Permafrost is defined as subsurface material that remains below 0o C (32o F) for at least two consecutive years. Because permafrost soils remain frozen for long periods of time, they store large amounts of carbon and other nutrients within their frozen framework during that time. Permafrost represents a large carbon reservoir that is seldom considered when determining global terrestrial carbon reservoirs. Carbon dioxide (CO2) and methane emissions from thawing permafrost could amplify warming due to anthropogenic greenhouse gas emissions. This amplification is called the permafrost carbon feedback. Permafrost contains about 1700 gigatonnes (Gt) of carbon in the form of frozen organic matter, almost twice as much carbon as currently in the atmosphere. If the permafrost thaws, the organic matter will thaw and decay, potentially releasing large amounts of CO2 and methane into the atmosphere. This organic material was buried and frozen thousands of years ago and its release into the atmosphere is irreversible on human time scales. Thawing permafrost could emit 43 to 135 Gt of CO2 equivalent by 2100 and 246 to 415 Gt of CO2 equivalent by 2200. Uncertainties are large, but emissions from thawing permafrost could start within the next few decades and continue for several centuries, influencing both short-term climate (before 2100) and long-term climate (after 2100).
"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," said Steiner, UN Under-Secretary General and UNEP Executive Director.
"Its potential impact on the climate, ecosystems and infrastructure has been neglected for too long," he added.
The UNEP report, Policy Implications of Warming Permafrost was designed to spur dialogue among climate-treaty negotiators, policy makers and the general public as they prepare to create a successor to the Kyoto Protocol that expires this year.
Carbon is not produced by permafrost. Organic carbon derived from terrestrial vegetation must be incorporated into the soil column and subsequently be incorporated into permafrost to be effectively stored. Because permafrost responds to climate changes slowly, carbon storage removes carbon from the atmosphere for long periods of time. Radiocarbon dating techniques reveal that carbon within permafrost is often thousands of years old.
Carbon stored within arctic soils and permafrost is susceptible to release due to several different mechanisms such as:
- Microbial activity releases carbon through respiration. Increased microbial decomposition due to warming conditions is believed to be a major source of carbon to the atmosphere.
- Methane clathrate, or hydrates, occur within and below permafrost soils. As permafrost temperature increases, clathrate may be released as methane.
- As air and permafrost temperatures change, above ground vegetation also changes. Increasing temperatures facilitate the transfer of soil carbon to growing vegetation on the surface.
The UNEP reports recommends the following:
1): Commission a Special Report on Permafrost Emissions. (IPCC) may consider preparing a special assessment report on how CO2 and methane emissions from thawing permafrost would influence global climate to support climate change policy discussions and treaty negotiations. All climate projections in the IPCC Fifth Assessment Report, due for release in 2013-14, are likely to be biased on the low side relative to global temperature because the models did not include the
permafrost carbon feedback.
2): Create National Permafrost Monitoring Networks: To adequately monitor permafrost globally, individual countries (Russia, Canada, China and the United States) may consider taking over operation of sites within their borders.
3): Plan for Adaptation: Nations with substantial presence of permafrost may consider developing plans evaluating the potential risks, damage and costs of permafrost degradation to critical infrastructure.
Besides the effects on overall global warming as the permafrost is defrosted, the land will shift causing damage to structures. For example pipelines laid over this territory may be destabilized.
"Infrastructure failure can have dramatic environmental consequences, as seen in 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," UNEP reports.
For further information see Permafrost.
Map image via UNEP.