We have been hearing the warnings for years from the scientific community - climate change is a threat to the immense tracts of forest that ring the Northern Hemisphere. Rising temperatures, drying trees and earlier snow melt all contribute to a growing number of wildfires.
The near-destruction of Fort McMurray in Northern Alberta this month was caused by a fire that forced nearly 90,000 people to flee. It is grim proof that the threat to these massive tracts of spruce and other resinous trees, collectively known as the boreal forest, is real. Scientists claim that a vast-scale loss of the forest could have profound consequences for the climate.
Taking a hard look back, it is clear that Fort McMurray was particularly vulnerable as one of the largest human outposts in the boreal forest. But the destruction of patches of this forest by fire, along with invasions by insects that are now surviving the warmer winters has occurred throughout the hemisphere.
Global warming is suspected as the prime culprit in the rise of this type of fire. The warming is hitting northern regions particularly hard: Temperatures are climbing faster there than for the Earth as a whole, snow cover is melting prematurely, and forests are drying out earlier than in the past. The excess heat may even be causing an increase in lightning, which often sets off the most devastating wildfires.
"It's clear that the warming temperatures and extraordinary drought are major players here," said Thomas W. Swetnam, an emeritus scientist at the University of Arizona who studies the ecology and history of wildfires. "We probably wouldn't be seeing the scale of some of these fires it weren't for these factors."1
The weather pattern known as El Niño has been pumping a huge amount of heat from the ocean into the atmosphere for more than a year. Scientists say that could also have played a role in setting the conditions for this year's fires. Temperatures in parts of Alberta were as much as 15 degrees Celsius higher than normal in the weeks before the fires began, destroying the landscape. One of the explanations for the increase in forest fires seems to be an earlier melting of the spring snowpack across the Northern Hemisphere, another trend identified by satellite imagery. The melt leads to a drying of the land early in the fire season, leaving trees easier to burn. Lightning then sets off intense fires that are nearly impossible to control.
Yet the same scientists say the overall increase in fire in northern regions would not be happening without global warming. The rising danger was predicted decades ago, as one consequence of human emissions of greenhouse gases (GHGs).
One of the scientists who published such a forecast in the 1950s, Brian J. Stocks, who retired from the Canadian Forest Service and is now a consultant, said that the worst was yet to come. "We're kind of at a crossroads," he remarked. "We anticipate more fires, and more intense fires, in the future."2
The situation he and other experts said, demands new thinking by governments about how to manage forests and protects nearby human settlements. Fort McMurray, for example, has just a single road for people to leave the city. But the dangers go far beyond the risk to the communities on the front lines, and they are global in scope.
The forests of the world are helping to offset rising of human output of GHGs, absorbing a significant portion of carbon dioxide that the burning of fossil fuels spews into the air. Even as fires and other disturbances increase, the forests are growing more than enough to compensate. But scientists see a risk that if the destruction of fires and insects keeps growing worse, the situation will reverse, and some of the carbon that has been locked away in the forests will return to the atmosphere as carbon dioxide. This will accelerate the pace of global warming and further magnify the stress on the forests - a dangerous feedback loop.
In addition, winds sometimes carry soot from the northern fires onto the immense sheet of ice covering Greenland, darkening the surface and causing it to absorb more of the sun's heat. In 2012, such soot contributed to melting the surface of virtually the entire Greenland ice sheet, the first time that happened since 1889. Should the ice sheet disintegrate entirely, it could raise the sea level by more than six metres.
Scientists have been trying for years to call attention to the boreal forest, which gets less public attention than tropical forests. It represents nearly a third of the forest land on the planet. It is ecologically unique, and vital to human welfare for its ability to limit the risks of global warming by soaking up some of humanity's GHG emissions.3
The boreal forest comprises mainly cone-bearing trees like pine, spruce and larch, each adapted perfectly to survive long, deep, cold winters. The forest encircles the Northern Hemisphere in a band near and just below the Arctic Circle, through Alaska, Canada, Scandinavia, and Russia. Across the hemisphere, the danger to the forest from global warming is being compounded by increased industrial activities. Fort McMurray, for instance, sprang up in recent decades as the commercial centre for a huge industry that is extracting some of the world's dirtiest oil from a region known as the Athabasca tar sands.
In Russia, extensive mining and drilling for fossil fuels are also damaging their forests. More people means more activity that can spark forest fires according to Sergei A. Bartalav, the director of a laboratory that helps monitor fires in Russia. But he added that the government had been slow to put in the necessary personnel and equipment to control any fires.4
Forest fires are a natural part of the ecology of the boreal forest, but records from recent years suggest they may be reaching an unnatural degree of frequency and intensity. Limited evidence from Alaska suggests that fires in at least part of the state are at their worst in 10,000 years. Official Russian figures do not show an increase of forest fires in recent decades. But American scientists have concluded that the official figures greatly underestimate the overall burned area.
I, amongst thousands of others can only hope the people of Fort McMurray and area can one day get out from under the horrible events that have befallen them. Good luck to you all.
1 Justin Gillis and Henry Fountain, "Climate Cited in Northern Fires" The New York Times International Weekly (May 21, 2016):
2 Ibid
3 Ibid
4 Ibid
