Records, permafrost and a warming country

Snag Junction, Yukon, on the Alaska Highway, not far from the Alaska line. Gordon Van Bibber is 71, Yukon-born, a trapper first and a trucker later. Down a gravel side road is what is left of an old airstrip. His father worked at Snag airport in February 1947, the week the thermometer there did something no thermometer in North America has done before or since.

So here's the question. How cold does Canada get, how hot, and what do the official numbers say is changing under our feet?

The extremes first, from Statistics Canada and Environment and Climate Change Canada. Coldest: Snag, Yukon, about minus 63 degrees, in February 1947, the lowest ever recorded in North America. Hottest: Lytton, British Columbia, 49.6 degrees, June 2021. The old mark, 45 degrees in Saskatchewan, 1937, had stood for 84 years. Sunniest: Estevan, Saskatchewan, about 2,500 sunshine hours a year.

Now the ground. Canada's Changing Climate Report, published by the federal government in 2019, says permafrost, ground that stays frozen year after year, underlies about 40 per cent of Canada's landmass. That permafrost has warmed, the report says: by about a tenth of a degree per decade in the central Mackenzie Valley, and three to five tenths in the high Arctic. Snow cover has shrunk. Summer sea ice has shrunk.

Same report: Canada's average temperature rose 1.7 degrees between 1948 and 2016, and 2.3 degrees in the North. In the report's words, both past and future warming in Canada is, on average, about double the magnitude of global warming, and more than half of it is attributed to human influence. Its projections run from 1.8 degrees to more than 6, depending on emissions.

Find it on the map. This is the Atlas of Canada's permafrost map, from Natural Resources Canada, in three bands. The dark band is continuous permafrost: frozen ground under everything. Below it, a wide band of discontinuous permafrost, frozen in patches; then sporadic. Follow the middle band east and notice how it dips south around Hudson Bay. Treat bands like these as contour lines: every edge is a threshold.

Let's change one fact. Add another two degrees to the North's average. The edges of the bands would creep north, and ground under roads and runways in the discontinuous zone would go soft in places. Think of the Tibbitt to Contwoyto winter road north of Yellowknife: about 400 kilometres, mostly on frozen lakes, closed for the season on April tenth, 2026. A road that exists only as long as the ice.

The mistake people make is saying permafrost is half the country. Older material said about half. The 2019 report, which is the government's own current statement, says about 40 per cent of the landmass. Use the newer number, and say where it came from. That is how you tell a fact from a habit.

Here's the rule, in one breath. Minus 63 to plus 49.6, frozen ground under four tenths of the country, and warming at about double the global rate, all by the government's own count.

This week, find the permafrost boundary on the course map and see which side your town is on. Most Canadians are surprised how far south the sporadic band reaches. Then look up the coldest and hottest temperatures ever recorded at your own weather station, in the climate normals. Your town has extremes too.

Next time, fire, flood, quake and storm: where each hazard sits on the map, and why.