A decade ago wildfires in Alaska were almost unheard of. Today, they’re an annual event.
Hundreds of wildfires are continually whipping across the state, leaving in their wake millions of acres of charred trees and blackened earth.
This year alone may be the state’s worst ever, with almost 5 million acres already burned — an area larger than Connecticut. Scientists say the fires are just the latest indicator of a climatic transformation that is remaking the state — its forests, its coasts, its glaciers, and perhaps most of all, the frozen ground beneath — more than any other in America.
Alaska has already warmed by more than 3 degrees Fahrenheit in the past half-century, much more than the continental United States. The consequences have included an annual loss of 75 billion metric tons of ice from its iconic glaciers — including those covering the slopes of Denali, the highest peak in North America — and the destabilization of permafrost, the frozen ground that underlies 80 percent of the state and whose thaw can undermine buildings, roads and infrastructure.
The devastating spike in Alaskan wildfires could cause the release of more stored carbon into the atmosphere. Alaskan boreal forests, wetlands and permafrost serve as an enormous carbon sink. But these large wildfires in Alaska are affecting forest’s ability to absorb carbon from the air and trapped them inside the trees.
Initially, it was thought that the effects of these wildfires are limited but now researchers believe they are more widespread and should be recognized as a significant driver of climate change and not just a side effect.
“The cold temperatures of Alaska have led over time to the storage of vast quantities of soil and biomass carbon,” said USGS scientist David McGuire. “A major concern for this region is how interactions among warming temperatures, permafrost thaw, more frequent wildfires, and changes in stream flow will affect carbon storage and greenhouse gas exchange.”
Alaska is a bigger storehouse for carbon in comparison to 48 lower states and accounts for about 18% of U.S. land mass. Currently, Alaska soaks up about 3.7 million metric tons of carbon per year but increase in permafrost thawing and more frequent and intense wildfires are causing to disrupt the whole process and making it difficult for Alaskan forests to even act as a moderate carbon sink.
Our scientists found that the balance of carbon storage versus release in Alaska was strongly linked with wildfires. In years where there was high wildfire activity the net carbon balance declined dramatically, and then it would rebuild in the absence of fire.” Virginia Burkett, USGS Associate Director for Climate and Land Use Change said.
The year 2015 was one of worst wildfire seasons in Alaska when almost 5 million acres were burnt. While fire activity in Alaskan forests has increased now, they could release more stored carbon into the atmosphere, which, in turn, increase greenhouse gas concentrations and potentially have global implications.
The first of its kind assessment by USGS reveals how wildfires are amplifying the carbon release form Alaska soil and vegetation and affecting climate change.
“This benchmark assessment establishes significant baseline information to better understand carbon dynamics in Alaskan ecosystems,” said Michael Connor, deputy secretary of interior. “Nowhere is this more critical than in Alaska with its vast and diverse geography and its heightened vulnerability to climate change.”