Our national parks do not exist in isolation. Air circulates, water flows, animals migrate and man-made pollution is indifferent to the boundaries it crosses, and the climate it alters, with effortless ease.

So it is right and necessary that the UNESCO world-heritage council has drawn attention to the risks facing Wood Buffalo National Park, an incomparable wilderness area straddling the borders of Alberta and the Northwest Territories, north of Fort McMurray.

Wood Buffalo is Canada's largest national park, the home to a herd of 5,000 wild bison and the breeding place for the endangered whooping crane, North America's tallest bird. One of the park's key resources is the Peace-Athabaska Delta, a huge wetland and meadow area that sustains the whooping crane and bison populations as well as supporting many other species of migratory waterbirds.

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The park was designated a world heritage site in 1983, which gives UNESCO a continuing interest in the threats that Wood Buffalo faces – a pressure that will only increase as oil-sands activity expands north along the Athabaska River toward the park's boundaries, and more water is diverted for industrial use.

In response to a petition from Alberta's Mikisew First Nation, UNESCO has acknowledged the threats posed by proposed megaprojects upstream from the sensitive delta area, including the Frontier Oil Sands Mine on the Athabaska and the Site C dam on the Peace. The UN agency has asked Canada not to take any decision that would be difficult to reverse, and also requested the federal government to submit a full environmental assessment of the projects' likely impact.

Looming over these requests is UNESCO's own counterthreat: that it could declare Wood Buffalo as being "in danger" and even take away the coveted heritage-site designation.

Wood Buffalo may look pristine in the literal, uncomplicated sense that development has been excluded from its territory – there are no open-pit mines for the bison to tumble into, and the whooping cranes don't have to dodge giant earth-movers. But when water is essential to the functioning of a healthy delta, and the extraordinary life it supports, what happens upriver invariably compromises nature's downstream health.

It's unfortunate that a First Nation community has to appeal to an international agency to get a Canadian park the hearing it deserves. What the world recognizes as heritage should be considered inviolate within its own land, and by its own government.