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Permafrost degradation occurs beneath shallower water than expected in northern Yukon

Methane escapes from a hole drilled through lake bottom sediment  (photo credit: Z. Braul)

A paper published by Roy-Leveillee and Burn (2017)  in the Journal of Geophysical Research- Earth Surface  reports observations of permafrost degradation and talik development beneath water depths less than 15% of the maximum ice thickness in lakes of Old Crow Flats, northern Yukon.  This is surprising as,  in the near-shore zones of thermokarst lakes, it is generally assumed that permafrost is sustained where water depth is less than 60% of the local maximum ice thickness.

 

 

 

Jet-drilling to delineate the talik permafrost boundary  (Photo credit: P. Roy-Léveillée)

The paper investigates controls on permafrost degradation and reveals that sub-lake permafrost is sensitive to on-ice snow distribution where the water column freezes through. It shows the importance of the thermal offset where conditions are marginal for talik initiation and highlights the role of interannual variability for prompt talik initiation near receding shores.

These findings improve understanding of permafrost degradation beneath shallow water, a topic of  particular concern in the context of climatic warming as methane release from thaw lakes is concentrated near receding lake margins and is most active at the thaw front beneath the lake bottom.

Emma presented her work on beaded streams at the CAG annual meeting at York U

On June 1st, 2017, Emma Ciric presented her research on beaded streams at the Canadian Association of Geographer Annual Meeting at York University. Her poster was very well done, particularly for a first poster (!), and can be viewed here. Emma has now graduated from Laurentian University and went on to pursue a MSc in Coastal and Marine Science at the University of Algarve, in Portugal.

Permafrost teaching lab: Doug’s scale model of oriented lakes

Douglas Massel is an undergraduate student from the LU Outdoor Adventure Leadership (ADVL) Program. Potentially interested in pursuing a career as a field technician for research expeditions in remote areas, Doug added a minor in Geography to his ADVL degree, and focused on physical geography courses. In the permafrost class this year, Doug is writing his term paper on the orientation of thermokarst lakes. He added a scale model experiment to his paper, to examine the hypothesis that sediment texture affects the direction of lake elongation in relation to dominant winds, as proposed in Roy-Leveillee and Burn, 2015. Doug has been busy in the lab blowing wind over trays of wet sand and silt with puddles in them to look at circulation and lake expansion patterns.

Doug’s scale model: wind is blowing (upper left), sediment is moving (bottom left), Doug is watching his lake expand.

 

In summer 2017 Doug will be working as a field assistant in the Canadian NW Arctic with Chris Burn from the Carleton Permafrost Group. Best of luck Doug, and send some photos!

 

 

 

Wrapping up the first permafrost course at LU

The new Laurentian University Permafrost course (GEOG4256) went well and was well attended, with 41 people registered in the class. Full time undergraduate students in the group were from a wide range of programs including Geography, Education, Environmental Sciences, Environmental Studies, Outdoor Adventure Leadership, Chemistry, Archeology, and Sports and Physical Education. A few mature students also joined the course, including people who have been involved in mining and reclamation work through careers in consulting, engineering, or geological techniques.

Group photo of the 2017 class for Permafrost (GEOG4256) at Laurentian University

Everyone has been working hard to learn the basic principles that control ground thermal regime, ground ice formation, and how permafrost responds to changes in surface conditions. The course was interspersed with hands-on exercises, opportunities for lab work, and assignments  aiming to familiarize students with basic tools for data analyses of ground thermal regimes or back of the envelope estimations of thaw and frost penetration in the ground. The equipment and facilities used were funded by Goodman School of Mines, who have been supporting efforts to develop a training program in permafrost science at Laurentian University.

Left to right: Liam prepares buckets of saturated sand for freezing; Brandon and Chris assemble a frost tube, and Justin prepares small samples of silt and clay for texture analysis.

Each student also worked on a research paper where s/he explored a topic linking their  interests or expertise to an aspect of permafrost. This year’s paper topics included:

  • the state of knowledge and common practices regarding building foundations, railway embankments, and frozen core dams in permafrost terrain;
  • the evolution of different permafrost landforms (pingos, ice wedges polygons, thermokarst lakes, and retrogressive thaw slumps);
  • the impacts of climatic change on permafrost, positive feedbacks, and methane emissions from thawing organics;
  • the state of permafrost knowledge and research in different regions of Canada and the world;
  • traditional knowledge and permafrost science;
  • wildfires and permafrost;
  • the impacts of frost heaving on the placement of artifact in relation to ground stratigraphy;
  • permafrost in political discourse and in the media;
  • risks and opportunities associated with methyl-hydrates;
  • mercury methylation in permafrost environments;
  • the integration of permafrost in the K-12 school curriculum.

Some of these projects, involved the use of GIS, remotely sensed imagery, or numerical modelling. Others included the development of scale models and experiments in the permafrost laboratory. Finally, some of the students from the Education program produced recommendations for the integration of permafrost-related topics in the Ontario K-12 curriculum, which will help train the next generation of Canadian permafrost scientists!

Josh and Emma (left) are launching data loggers to monitor ground surface temperatures and Doug (right) adjusts the water table in his scale model of oriented lakes.