Wildfires becoming more common on Alaska tundra
25.02.2013 - Flora & Fauna, Arctic
Results of a research study published in IOP Science led by Adrian Rocha form the University of Notre Dame in Indiana show that over the past 50 years, wildfires have become more common in Alaska, which in turn could have effects on the climate.
Normally associated with hot regions, the number of forest fires in cold regions – even regions without trees – has altered the outlook of scientists. A 2007 fire on Alaska's North Slope at the Anaktuvuk River burned 1,000 km2 of tundra – the same amount of tundra that had burned in the half century before the fire. 2010 saw 37 fires in the Noatak tundra region in northwest Alaska burn 440 km2.
Wildfires are important to monitor because they can contribute to further climate warming. Firstly, they release carbon that has been sequestered into the atmosphere. Secondly, they burn areas that are normally covered in snow and are thus highly reflective. Along with the black carbon (soot) they produce, which, when it lands on snow and sea ice in the region, reduces their ability to reflect solar energy back into space, this reduces the overall albedo of the region, allowing more solar energy to be absorbed and thus increasing warming.
Using data on wildfires collected by the US Bureau of Land Management and satellite data, the researchers determined to what extent reflectivity of the region and its vegetation had been affected over time. The results of the study show that plant productivity is likely to increase in the decade following a tundra fire, often growing back to a greater extent before the fire. Increased productivity means more carbon is taken up from the atmosphere as plants grow back.
Yet the team also found a long-term increase in the depth of seasonally thawing permafrost. Due to an increase in decomposition in organic material in the soil as it thaws and releases carbon into the atmosphere as methane and carbon dioxide, this process can lead to more warming in the long term.
So while the scientists involved in the study believe increased fires will have a greater effect on the climate in the future, they are not able to say whether it will have a positive or negative impact. Rocha says "to expect the unexpected" in a world where the cliamte is changing.