Canadian Geographic
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International polar year

Crossing the lines

How will a receding tree line and melting permafrost affect life and land in the North?

You may recognize Canada’s North by the intricate coastlines and political borders drawn on a map, but much of this region’s extraordinary landscape is defined by two other important boundaries: the tree line and the permafrost line. Now these crucial limits appear to be shifting significantly, with the potential for even more significant changes to life in some parts of the region. That is why researchers working on International Polar Year (IPY) projects have been in the field from the St. Elias Mountains in Yukon to the Mealy Mountains in Labrador, trying to learn more about the impact of climate change on the landscape of the North.

About 40 percent of Canada’s landmass is above the tree line, which marks the limit of forests and the beginning of the Arctic tundra. Exactly where that happens not only depends on latitude and altitude but also factors such as availability of water, temperature, soil type, and protection from wind and animals. Given the various factors involved, the tree line therefore ends up as a jagged border that can be seen stretching across higher latitudes. With climate change and warming temperatures, the tree line has been moving northward over the past few decades. This could affect the way animals move around, or provide a setting hospitable to new plants and wildlife. Different types of insects might begin to make their way into this new territory.

Permafrost represents another boundary that is moving. Warming patterns have intermittently thawed many parts of the large areas of permafrost. The result, called discontinuous permafrost, can yield dramatic effects. Meltwater can lubricate the underside of the topsoil, causing sizable sections of it to slide down slopes and leave piles of debris at the bottom. If enough of this material fell, even the course of a river could be blocked.

IPY-sponsored research has been examining how such disturbances can alter the face of the tundra. Will wildlife behaviour change? Will the growth of vegetation trigger more fires? At the same time, carbon dioxide being released by large volumes of melting permafrost could make a major contribution to the processes responsible for climate change.

Such trends could eventually alter not just the appearance of many parts of the North but the lifestyle of the people who live there: how they move from place to place and how they construct buildings. It all adds up to new challenges, as well as new prospects.


This vignette delves into the growing concerns of the Earth’s permafrost thawing due to climate change, and what impact it will have on our planet’s ecosystems. The significance of The Old Crow Flats are also mentioned in this piece.


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Quiz :

Which Northern animal has been extensively tracked using satellites?

Arctic hare
Arctic fox