Long-Term Monitoring of Permafrost Temperature, Active Layer Thickness and Surface Settlement in the Mackenzie Valley, NWT

Presenter:

 

Caroline Duchesne – caroline.duchesne@canada.ca

 
 

Authors:

 
C. Duchesne – Geological Survey of Canada, Ottawa, ON, Canada
S.L. Smith – Geological Survey of Canada, Ottawa, ON, Canada
H.B. O’Neill – Geological Survey of Canada, Ottawa, ON, Canada
J. Chartrand – Geological Survey of Canada, Ottawa, ON, Canada
 

Summary:

A permafrost and active layer monitoring network, established in the Mackenzie Valley and Delta (NWT) by the Geological Survey of Canada, has been maintained since the 1980s. This poster highlights permafrost temperature and active layer trends over the past 30 years. In the continuous permafrost zone, permafrost at most sites has been warming at a rate greater than 0.05°C per year. In warmer permafrost of the discontinuous zone, change in ground temperature is less than +0.03°C per year. Comparison of current ground temperatures to the baseline established during IPY (2007-09), indicates that permafrost at many sites is currently warmer than during IPY, with smaller change where temperatures are close to 0°C and permafrost is ice-rich due to latent heat effects. The active layer thickness, which exhibits greater inter-annual variation than deeper ground temperature measurements, has generally increased since 2008. Analysis of long-term changes in thaw penetration and ground surface elevation for 17 sites in the Mackenzie Delta has also shown significant subsidence at more than half of the sites due to melting of excess ground ice. This long-term data collection provides information to improve the characterization of regional baseline ground thermal condition.

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