The Theme
Peat is a material consisting largely of organic residues, originating
under somewhat water-saturated conditions through the incomplete
decomposition of plant and animal matter. Peatlands are defined
as areas that form massive deposits of peat - peat thicknesses reach
at least 40 centimetres. Much of Canada's peatland area lies atop
permafrost. Approximately 12% of the Canadian landmass is covered
with peatlands.
At present, peatlands are natural sinks of carbon. With global warming, however, they have the potential to become immense sources of greenhouse gases due to the lowering of the water table and, with the associated feedback mechanism, to contribute significantly to further warming. This map shows the sensitivity of peatlands to climate warming. This map shows
the sensitivity of peatlands to climate warming.
Sensitivity Projection
Approximately 60% of the peatlands in Canada lie within areas that
are expected to be severely affected by climate warming. The geographic areas where peatland will be most affected are the Hudson Bay lowlands, the Mackenzie River valley region and the northern parts of Alberta and Manitoba.
In terms of ecoclimatic provinces, the most pronounced changes
are expected to occur in the Boreal, Sub-Arctic and Arctic regions.
In these regions, many peatland areas are found overlying permafrost.
With warming, it is likely that the upper part of the permafrost
would melt and much of the surface water that is essential for peatland
development would drain thereby allowing the peat to decompose.
This would result in a decrease in methane production and an increase
in the release of carbon dioxide. On the other hand, a deep-enough
thaw of permafrost would allow hydrates to thaw and thereby produce
methane. Thus the depth of both the permafrost and the peat are
important in determining the amount of greenhouse gas production.
At the same time, the poor drainage conditions and subsidence associated
with thawing are expected to increase the problems for construction
and maintenance of buildings, highways and pipelines in these northern
regions.
Data Source
Tarnocai C., I.M. Kettles, and B. Lacelle. 2000. Peatlands of Canada.
Geological Survey of Canada, Open File 3834. Scale 1:6 500 000.
Ottawa. Natural Resources Canada.
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