Thursday, May 14, 2020

Melting Borders

The border between Alberta and British Colombia is moving. This shifting border has nothing to do with any territorial dispute between the two Canadian provinces. It is moving because it lies across the Haig glacier. And the Haig glacier is melting.

The boundary between Alberta and British Colombia is determined by the hydrological divide, that is "the spot where a raindrop at the highest point either falls west into B.C. or east into Alberta". However as the glaciers melt the hydrological divide can shift, so that runoff which once flowed in one direction will now flow in another direction as rock formations, preciously covered by ice, are revealed.

This process is beautifully visualized in CBC News' How a melting glacier could redefine the Alberta–B.C. border. Using a 3d map of the Haig glacier CBC shows how the glacier is melting and causing a shift in the border between B.C. and Alberta. Of course this shift in the boundary is pretty insignificant but it does provide a gripping introduction into the real story about how global heating is causing Canada's glaciers to melt. The Haig glacier is losing about a metre a year and is projected to completely disappear in the next 80 years.

A shrinking glacier can have a dramatic impact on those living nearby. For example Calgary relies on glacier melt to provide up to 20% of its water supply during times of drought. Across the border in B.C. hydro-electric power stations also depend on water flow determined by the Haig glacier.

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