The last few years have seen the forests of Alaska and North America go up in smoke with increasing frequency. This situation was one of the predicted results of a warming climate, as the increasing temperatures turn parts of the state into a tinderbox. But the sharp spike in wildfires seen in recent years is no longer a side effect of climate change, claim researchers, it is now a driving force.
The contribution of the burning trees and soil of the boreal forests – which store vast amounts of carbon – to climate change is, according to the researchers, a subject that has received worryingly little attention. The report, compiled by the US Geological Survey, shows how this last season in Alaska has seriously altered the balance between carbon sequestration and release within the northern ecosystem.
The importance of Alaska's land in stabilizing the climate cannot be understated. While its land area only covers around 18 percent of the US, the frozen permafrost and boreal forests contain roughly 53 percent of the nation’s carbon, and is thought to absorb around 3.7 million tonnes (4.1 million tons) of the stuff every year. And with the Arctic and the far north warming at twice the rate of the rest of the planet, this has the potential to cause serious damage and drive climate change even further.
“Carbon stored in high-latitude ecosystems is considered more vulnerable than carbon sequestered in ecosystems in the temperate zone,” explains Virginia Burkett, associate director for climate and land use change at the US Geological Survey, “because average temperatures are projected to increase faster in the boreal and arctic regions during the remainder of the century. This new assessment specifically reveals how soil carbon losses in Alaska are amplified by wildfires, which have increased in size and frequency with the warming Arctic climate.”
The fires that burnt their way through the state last year destroyed more than 20,200 square kilometers (7,800 square miles) of forest, making it one of the state's worst wildfire seasons ever recorded. But it is not just the burning of the trees that worries experts. Permafrost covers around 80 percent of Alaskan ground, and holds within it massive reserves of methane. When the soil thaws, it releases this into the atmosphere, further exacerbating the situation. The report aims to set a baseline for the region, so that future impacts of climate change can be measured against its current state.
Main image: U.S. Department of Agriculture/Flickr CC BY 2.0