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Proactive disclosure Print version   | |  Permafrost Permafrost and Climate Change
GSC permafrost and climate change research is focused on national sensitivity mapping, regional studies in the Mackenzie Valley, monitoring and modelling activities, assessment of the impacts of permafrost warming, and adaptation. The research team has recently produced a document highlighting ongoing and newly-proposed studies summarized under 4 main research themes: Physical Processes, Thermal Regimes, Carbon Sources and Sinks, and New Initiatives. [Click on an image thumbnail to view a larger image, notice]
Permafrost is a thermal condition - its formation, persistence or disappearance are highly dependent on climate. Its distribution, temperature and thickness respond to natural environmental changes and anthropogenic disturbances that cause an alteration to the ground thermal regime. Changes in air temperature and/or precipitation, or surface disturbances due to clearing of vegetation, removal of insulating organic layer, forest fires, river channel migration, shoreline erosion all may produce a modification to the ground thermal regime. The interaction between climate above the ground and climate below the ground is complex, and dependent on several factors, many of which are affected by climate change. Changes in climate above the ground are most often dampened below the ground due to the insulating effects of vegetation, organic material or snow cover. There is generally a lag between a change in temperature at the ground surface and the change in permafrost at depth; for thick permafrost this lag may be on the order of hundreds to thousands of years, for thin permafrost, years to decades. The GSC's ongoing monitoring programs in the Mackenzie Region focus on studying the interaction between permafrost and climate. Not all permafrost in existence today is in equilibrium with the present climate. Offshore permafrost beneath the Beaufort Sea is several hundred metres thick and was formed when the shelf was exposed to cold air temperatures during the last glaciation. This permafrost is presently in disequilibrium with Beaufort Sea water temperatures and has been slowly degrading. Permafrost occurrence in the southern fringe of the discontinuous zone is closely related to peatland type, underlying peat bogs whereas fens remain unfrozen. In the upper Mackenzie Valley, permafrost several metres thick under peat plateaus is in disequilibrium with the present climate and has been slowly disappearing in response to climate warming since the Little Ice Age. The presence of the insulating peat vegetation greatly affects and reduces the rate of its degradation.
General circulation models predict that, for a doubling of atmospheric concentrations of carbon dioxide due to anthropogenic sources, mean annual air temperatures may rise up to several degrees over much of the Arctic. In the discontinuous permafrost region, where ground temperatures are within 1-2 degrees of melting, permafrost will likely ultimately disappear as a result of ground thermal changes associated with global climate warming. Where ground ice contents are high, this permafrost degradation will have associated physical impacts. Of greatest concern are soils with the potential for instability upon thaw (thaw settlement, creep or slope failure). Such instabilities may have implications for the landscape, ecosystems, and infrastructure. An assessment of the impact of climate change on permafrost is necessary in order to determine whether adaptation measures will be required.
[Click on an image thumbnail to view a larger image, notice]
The sensitivity of permafrost to climate warming is a component of a series of national syntheses of geological responses to climate change currently being prepared by the Geological Survey of Canada. Previous studies have predicted the equilibrium permafrost zone boundaries under 2xCO2 conditions assuming a spatially uniform increase in ground surface temperature of the same magnitude as that predicted for air temperature under specific warming scenarios. The GSC study examines the sensitivity of permafrost to warming by considering the main factors that determine the response of the permafrost thermal regime to warming and the impact of any permafrost thaw that occurs. Geographic Information System (GIS) techniques have been used to produce maps classifying areas according to 1) the thermal response to warming: the relative rate and magnitude of ground temperature change, and 2) the physical response: the relative magnitude of the impact of permafrost thaw. A final map will then combine these two components into one sensitivity index. View Poster [PDF, 3.6 Mb, viewer]
The Western NWT has experienced over the last century the greatest increase in air temperatures in all of Canada (1.7°C). Much of permafrost is at temperatures very close to the melting point of ice, and processes triggered by thawing ground ice are sensitive to warming, particularly where ice contents are high and the potential for soil instability upon thaw exists. The interaction between climate above and below the ground is complex, and dependent on several factors, many of which may also be affected by global change.
Much of the area of discontinuous permafrost is already in disequilibrium with the current climate and is still responding to changes of the last century. Permafrost is dynamic and will respond if climate continues to change as anticipated in the years and decades to come. The GSC has established a network of study sites in the Mackenzie Valley for monitoring the impact of climate change on ground temperatures and the active layer. This research will improve our understanding of permafrost-climate interaction and our capability to predict permafrost response to future climate change. However, it must be completed by a clearer understanding of how processes such as sediment transport in rivers, slope failure, and ground subsidence will also be affected by climate change. This understanding is necessary for the proper development and design of infrastructures in the North. In response to concerns about the effects of global climate warming, the Mackenzie Valley is one of three regions selected for the GSC's "Integrated Research and Monitoring Area" (IRMA) program. The objective of this program is to identify regions of Canada with geologic conditions or processes especially sensitive to climate warming and to determine the response of these conditions and processes to this change. Specifically, the purpose of the Mackenzie IRMA is to reconstruct the climate since the end of the Laurentide Ice Age (~ 13,000 yrs. BP) based on the relationship between climate and vegetation, to produce maps of permafrost and ground ice distribution, and to determine the sensitivity of landscape-altering processes to climate warming. The Mackenzie Valley IRMA report is a synthesis of information about permafrost in the Mackenzie Valley.
Monitoring activities are essential to document and map permafrost conditions spatially and temporally, to further understand permafrost climate relationships, and to provide data for the validation of spatial distribution models and their predictions. GSC's permafrost monitoring sites are concentrated in the Mackenzie Valley and Delta. Additional sites exist elsewhere in the north, for example at Baker Lake, Nunavut in collaboration with the community and the University of Toronto, and at Alert (Ellesmere Island, Nunavut) in collaboration with the Department of National Defence. The Alert sites, established in 1978, are the northernmost permafrost observatories in the World and amongst the longest running in Canada. View Poster [ZIP, 3.5 Mb] on GSC Monitoring Activites in the Western and High Arctic
A National Sensitivity Mapping project looks at both thermal and physical (thaw settlement) impacts, while regional studies in the Mackenzie Valley, in addition, examine geomorphic processes. The process studies not only address the association with current climate and the response to future climate conditions, but also include a component of paleo-environmental research. GIS based modelling and mapping techniques being developed and validated for the Mackenzie Valley are being applied to the regional prediction of equilibrium permafrost distribution and thickness under various climate warming scenarios.
Site specific one dimensional transient modelling has also been undertaken at a few select sites in the Valley, to assess the magnitude of ground temperature change, the rate of increase in thaw depth, and the associated thaw settlement. A pilot project was initiated to develop an approach to assessing the impact of climate change on permafrost in northern communities and the sensitivity of infrastructure to the associated ground temperature warming, active layer increase or permafrost degradation. The predicted thaw depths shown above, are plotted as a function of time for three climate change regimes, a linearly rising temperature change, an exponentially rising change, and a linear change with 10% more snowfall. The plots show the rate of increase in maximum annual thaw depth over the 50-year simulation period. In all simulations, the rate of change in thaw depth is very slow in the first 10 to 20 years of the simulations. This observation suggests that detection of the early impacts of warming by monitoring thaw depth may be difficult, particularly when allowing for seasonal variations and when dealing with permafrost temperatures near 0°C where heat associated with phase change plays an important role in the ground thermal regime. State of Canadian Cryosphere -Permafrost Climate Change Indicators -Permafrost [PDF, 18.4 kb, viewer] Papers on response of active layer and permafrost temperatures to warming during 1998:
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