An expedition to Canada to investigate the thawing of frozen peatlands (permafrost)) in the land of polar bears.

In the region surrounding the village of Churchill, in northern Manitoba (Canada), a frozen peatland is currently thawing under the effect of climate warming. Peatlands are major carbon sinks. Aerial photo by Antoine Séjourné©

Climate warming is occurring three times faster in the Arctic than elsewhere on the planet. Today, the permafrost of northern Canada’s peatlands is beginning to thaw. As important carbon sinks, peatlands help regulate atmospheric CO₂ and are therefore key allies in the fight against climate change. However, permafrost thaw strongly affects the functioning of Arctic and subarctic peatlands.

Organic carbon and inorganic elements—representing nearly 50% of the total carbon stored in terrestrial soils—that were previously trapped in the frozen ground are now being released into aquatic systems. Microorganisms convert this newly available, highly biodegradable organic carbon into greenhouse gases, further amplifying global warming.

The PEACE project aims to understand how permafrost degradation and the resulting vegetation changes affect the carbon–nitrogen–phosphorus (C–N–P) dynamics of Arctic ecosystems. To achieve this, it brings together researchers from several French laboratories (Toulouse, Paris, Saclay, Rennes, Montpellier) and Canadian partners (Sherbrooke) within an interdisciplinary framework focused on the Critical Zone.

Active thawing of permafrost (frozen peatland) along polygonal structures at the edge of a lake. A new wetland area (dark zone) formed within a single year as a result of permafrost thaw. Drone photo by Antoine Séjourné©

The aim of the mission was to study carbon release along the peatland–soil–pond continuum by measuring greenhouse gas concentrations and identifying microbial communities. Permafrost thaw was characterised using drone surveys and by comparing current imagery with historical aerial photographs. The structure of the permafrost was determined through core drilling and geophysical surveys.

Field measurements: electrical resistivity/conductivity of the permafrost (linked to its ice content) and CO₂ and CH₄ concentrations in a degrading zone. Photo by Antoine Séjourné©

This new site will be compared with others already studied, such as those in the Yukon, in western Canada. New questions are emerging: what are the specific responses of these peatlands to permafrost thaw? What will be the impacts of this thaw on the carbon cycle, and therefore on the climate? These are the questions that scientists in the project are now addressing.

Coring in the frozen peatland (permafrost), where peat (sphagnum) and ice are exposed. Photo by Antoine Séjourné©

As a bonus to the research work, the French–Québec team also enjoyed the spectacle of northern lights and polar bears — from a safe distance, of course.

Northern lights at the Churchill Research Station. Male polar bears resting after a meal. Photo by Antoine Séjourné©

Sources : https://prismarctyc.com and https://www.pepr-faircarbon.fr/projets/projets-laureats-de-l-appel-a-projets-faircarbon/peace