USA — A spate of wildfires in Alaska has since quieted down after an active summer, but the environmental impact of the blazes may stretch for years.
Roughly 9million acres of forest burned in the US so far this year, up from a 6,250,000 acre average over the last ten years.
The increase in acreage, however, is coming from a smaller number of fires, with each incident engulfing more and more trees before being put out.
A team of scientists says that the land left in the wake of the flames could carry scars long after trees grow back, with the intensity of the fires permanently changing the Arctic, and global, climate.
This year marks the seventh time that more than 8million acres have burned, in the years after 2000.
Almost 10million acres, 9,873,745, burned in 2006, the most destructive year.
Alaska’s particularly active wildfire season has helped make this year’s outsized total, with more than 5million acres burning this summer.
Scott Goetz, a scientist at Woods Hole Research Center in Massachusetts, told PRI that the increase in fire activity has come from climate change and warmer, drier air that leads to more intense fires.
The Woods Hole website says that ‘if trends continue as predicted, [warming and drying] are likely to induce feedbacks that may further influence the global climate’.
The fires may have the more acute effect of speeding up changes in the Arctic climate as well, with the scientist saying that fires may unleash large amounts of carbon contained in permafrost areas.
Wildfires burn away layers of soil and peat that insulate the permafrost.
Goetz said that degrading the permafrost and severe wildfires could unleash ‘enough emissions to the atmosphere that it’s equivalent to another United States in terms of total emissions from fossil fuels’.
Woods Holes’ Max Holmes said that the greenhouse gas release could have ‘catastrophic global consequences’.
Beyond increasing the intensity of fires, the warmer conditions in the Far North may be leading to decreased ‘productivity’ in the forests that don’t grow as well in the heat.
Satellite images show ‘browning’ over belts of the interior Alaskan and Canadian boreal forests, or taiga, meaning few trees are growing there.
While browning is seen in some southern parts of the North American taiga, there has been an increase in trees in more northern regions that usually see less vegetation.
Goetz told PRI that while more trees in tropical areas are probably a good thing, increased presence in the Arctic will not take a large amount of carbon out of the air and change the ‘energy balance’ of the northern climates.
He said that the new trees are ‘much darker than the other vegetation there, and they absorb a lot more solar energy, and they retain that energy, so it warms the surface’.
‘It sets the system on a whole new course,’ Goetz previously told CBS