In warming North, less ice and more fire
Increased risk of blazes linked to human factors
There is a new normal in the North, climate scientists confirmed late last year. While average temperatures were relatively cool across the Arctic last summer, according to the Arctic Report Card, an annual compendium of peer- reviewed research on climate change and the North, the long-term trend remained the same.
Winter keeps coming North of 60, the authors report, but decade over decade it’s coming with warmer air, warmer water, less ice and, as it turns out, more fire.
Stock images of the warming North have been drilled into our collective psyche. Melting glaciers, skinny bears and mushy tundra have all become something close to cliché. But to many, the idea of more fire — in the land of ice — may be new.
What it shouldn’t be is a surprise.
The relationship between fire and climate is “strongly non- linear” in the North, the report says. But over time, the correlation is clear. When mean temperatures in July have exceeded 13.4 C over the past 30 years, the odds of fire have gone up significantly.
There are two big things at play here: more lightning and more fuel. According to one study cited in the report, lightning ignitions in the Northwest Territories and Alaska have gone up two to five per cent per year since 1975.
That’s partially because as summers in the North have become longer and hotter, they’ve become stormier too. “Higher temperatures also spur more thunderstorms,” study author Sander Veraverbeke told NASA’s Earth Observatory website last year. “Lightning from these thunderstorms is what has been igniting many more fires in these recent extreme events.”
Thanks to climate change, all that lightning is also striking drier, more fertile ground. Summers in the North are starting earlier and lasting longer. The snow-free season in Alaska is increasing by about five days per decade, according to a 2011 study. That means the distinctly flammable north- ern earth has more time to dry out.
Even small changes in the temperature can have a big impact on the flammability of the northern soil.
“High latitude ecosystems are characterized by unique fuels,” the authors write, “in particular, fast-drying beds of mosses, lichens, resinous shrubs, and accumulated organic material (duff ) that underlie dense, highly flammable conifers. These understory fuels cure rapidly during warm, dry periods with long daylight hours in June and July. Consequently, extended periods of drought are not required to increase fire danger to extreme levels in these systems.”
Not only are more fires starting in the North, they’re burning longer and consuming more ground. In 2015 in Alaska, 5.1 million acres burned. That was the second-worst fire season on record in the state, exceeded only by 2004, when 6.2 million acres burned.
A 2016 study attributed that annus horribilis to a confluence of predictable factors. An unseasonably warm spring led to an early snow melt. A heat wave in June dried out the surface and subsurface fuels. Then a sudden cluster of unusual storms caused a cavalcade of lightning strikes.
“During this period, 65,000+ strikes in Alaska gave rise to nearly 270 ignitions of the preconditioned fuels,” the authors wrote. Things probably would have been much worse had an unusually wet July not put an early end to the fire season that year.
The authors of that study concluded that human- induced climate change likely played a significant role in the carnage. By their analysis, “2015’s fuel conditions reached a level that is 34 per cent to 60 per cent more likely to occur in today’s anthropogenically changed climate than in the past.”
What’s more, things are only likely to get worse. Climate models cited in the report card predict up to a fourfold increase in area burned in the North by the end of this century.
The ice isn’t just melting anymore, in other words. The North is on fire.