|Title||Changing thermal state of permafrost in northern Canada
|Author||Smith, S; Duchesne, C; Ednie, M; Lewkowicz, A G|
|Source||Arctic Change 2014, oral presentation abstracts; 2014 p. 171-172|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20150020|
|Meeting||Arctic Change 2014; Ottawa; CA; December 8-12, 2014|
|Province||Yukon; Northwest Territories; Nunavut; Quebec; Northwest Territories; Yukon; Nunavut|
|NTS||15; 16; 25; 26; 27; 28; 29; 35; 36; 37; 38; 39; 45; 46; 47; 48; 49; 55; 56; 57; 58; 59; 65; 66; 67; 68; 69; 75; 76; 77; 78; 79; 85; 86; 87; 88; 89; 95; 96; 97; 98; 99; 105; 106; 107; 115; 116; 117; 120; 340;
|Lat/Long WENS||-180.0000 180.0000 90.0000 60.0000|
|Subjects||environmental geology; surficial geology/geomorphology; Nature and Environment; permafrost; freezing ground; ground ice; ground temperatures; climate, arctic; climatic fluctuations; climate; thermal
analyses; temperature; Climate change|
|Program||Climate Change Geoscience Essential Climate Variable Monitoring|
|Abstract||Changes in permafrost temperature is an important indicator of the state of permafrost and of a changing climate. Permafrost temperatures have been measured in boreholes across northern Canada for three
decades. The International Polar Year (IPY) provided the opportunity to enhance the permafrost monitoring network which now consists of over 150 boreholes representing the wide range of vegetation, geological and climate conditions found in the
Canadian permafrost regions. A snapshot of the thermal state of permafrost was also developed during IPY (2007-09) which provided a baseline against which future change can be measured. Recent permafrost temperatures measured in 2013-14 have been
compared to the IPY snapshot to evaluate the change in permafrost thermal state that has occurred since IPY. This change has also been examined in the context of the longer term record that exists for some monitoring sites.|
temperatures, measured at or close to the maximum depth of season variation, at many sites are higher than those measured during IPY. However, the greatest change is found in colder permafrost especially in the eastern and High Arctic. For example at
sites established during IPY in the Baffin region of Nunavut where permafrost is at temperatures between -5 and -15°C, current temperatures at 15 m depth are up to 1°C higher than that measured during IPY. Although the record for these sites is short
this recent change in permafrost temperature is consistent with that observed in the longer record for Alert in the High Arctic which shows a general increase in permafrost temperature since 1980s with a greater rate of increase (about 1.5°C per
decade at 15 m depth) since 2000. Air temperature records from Alert indicate that some of the highest air temperatures on record have occurred since 2000 with 2009-2012 being among the warmest years on record. This recent warming is likely
responsible for the increase in permafrost temperatures observed over the past decade.
Change in permafrost temperatures since IPY has been smaller in northwestern Canada. For sites in the continuous permafrost zone of the northern Mackenzie
region, increases in permafrost temperature generally less than 0.2°C have been observed. In warm permafrost in the discontinuous zone, of the Mackenzie Valley and southern Yukon, little or no change in permafrost temperature has been observed. The
longer records available for sites in the Mackenzie Valley indicate a general warming of permafrost since the 1980s but temperatures have increased at a lower rate since 2000 partly due to lower air temperatuers following a peak in 1998. At sites
where permafrost is at temperatures close to 0°C, energy is largely used to thaw the ground and degradation of warm permafrost has been observed since IPY.
In general, warming of permafrost is continuing across northern Canada. These changes in
permafrost thermal state and degradation of warm permafrost have implications for ecosystems, infrastructure and communities. The ongoing data collection from the monitoring network provides essential information to plan and adapt to these changes.
|Summary||(Plain Language Summary, not published)|
Permafrost temperatures measured across Canada in 2013-14 are compared to the baseline established during the International Polar Year (IPY, 2007-09).
Permafrost has warmed since IPY at several sites with the greatest change occurring in the cold permafrost of the eastern and high Arctic. Little or no change has been observed in warm permafrost of the Mackenzie Valley and southern Yukon but some
degradation of permafrost has been observed. These results are consistent with those from long-term records of permafrost temperature collected over the last 2 to 3 decades and indicate that permafrost warming is continuing. This warming and thawing
of permafrost has implications for ecosystems and infrastructure in northern Canada.