Newspaper article International New York Times

Northern Wildfires Tied to Climate Change ; Canadian Blaze Signals Latest Threat of Global Warming, Scientists Warn

Newspaper article International New York Times

Northern Wildfires Tied to Climate Change ; Canadian Blaze Signals Latest Threat of Global Warming, Scientists Warn

Article excerpt

Scientists say the threatened destruction of the Canadian city of Fort McMurray last week by a wildfire is the latest indication that the vital boreal forest is at risk.

Scientists have been warning for decades that climate change is a threat to the immense tracts of forest that ring the Northern Hemisphere, with rising temperatures, drying trees and earlier melting of snow contributing to a growing number of wildfires.

The destruction of neighborhoods in a Canadian city last week by a fire that sent almost 90,000 people fleeing for their lives is grim proof that the threat to these vast stands of spruce and other resinous trees, collectively known as the boreal forest, is real. And scientists say a large-scale loss of the forest could have profound consequences for efforts to limit the damage from climate change.

In retrospect, it is clear that the city, Fort McMurray, in northern Alberta, was particularly vulnerable as one of the largest human outposts in the boreal forest. But the destruction of patches of this forest by fire, as well as invasions by insects surviving warmer winters, has occurred throughout the hemisphere.

In Russia, about 70 million acres burned in 2012, new statistics suggest, much of that in isolated areas of Siberia. Alaska, home to most of the boreal forest in the United States, had its second- largest fire season on record in 2015, with 768 fires burning more than five million acres.

Global warming is suspected as a prime culprit in the rise of these fires. The warming is hitting northern regions especially 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 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 if it weren't for those factors."

The weather pattern known as El Nino has been pumping a huge amount of heat from the ocean into the atmosphere for more than a year, and 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 30 degrees Fahrenheit above normal in the weeks before the fires began, desiccating the landscape.

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 of the likely consequences of human emissions.

One of the scientists who published such a forecast in the 1990s, Brian J. Stocks, who retired from the Canadian Forest Service and is now a consultant, said this week that the worst was yet to come.

"We're kind of at a crossroads," he said in an interview. "We anticipate more fires, and more intense fires, in the future."

The situation, he and other experts said, demands new thinking by governments about how to manage forests and protect nearby human settlements. Fort McMurray, for instance, 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 help to offset rising human emissions of greenhouse gases, absorbing a significant portion of the carbon dioxide that the burning of fossil fuels throws into the air. So far, even as fires and other disturbances increase, the forests are growing more than enough to compensate. …

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