Arctic border on thin ice Canada's defence at risk with loss of brutal cold

In early February, during the depths of winter, Twin Otter aircraft belonging to the Canadian military flew over the vast expanse of the western Arctic looking for sea ice.

- Leyland Cecco

In early February, during the depths of winter, Twin Otter aircraft belonging to the Canadian military flew over the vast expanse of the western Arctic looking for sea ice. Below, sheets of white extended beyond the horizon. But the pilots, who were searching for a suitable site to land a 34-tonne Hercules transport plane a month later, needed ice that was 1.5 metres (5ft) thick. They could not find any.

The teams scoured 10 other possible spots, stretching as far west in the Arctic as Herschel Island, off the coast of Canada's Yukon territory. In the end, no site proved suitable for a sea-ice landing area. The north, it seemed, was too warm.

That same month, the cold was thwarting plans to move soldiers across the tundra as part of the same mission. It had grounded transport helicopters. It had broken snowmobiles and other equipment and, at times, spirits. The north, it seemed, was too cold for the materiel the military had hauled up to the tundra.

For generations, the intense cold of the Arctic has served as the bulwark of a military defence of the north. But a rapidly changing climate, defined by extreme shifts in temperature in both directions, threatens that defence, replacing it with a land and seascape more volatile and far less predictable.

Over February and March, hundreds of soldiers from several countries gathered in Canada's western Arctic for Operation Nanook, a military exercise meant to show that allied nations including the US, Finland, Sweden, Belgium and the UK could "sustain force" in the region, testing cutting-edge equipment in the tundra.

In recent months, political leaders have revived longstanding fears that Canada has only a tenuous hold over its northern border. Despite the spectre of hostile nations creeping over unseen borders, however, the biggest threat facing the troops was the freezing temperature.