While heat and drought are less pronounced in Europe this summer than in 2018 and 2019, other parts of the Northern Hemisphere are receiving record temperatures and very little precipitation. This situation causes large forest fire events in many regions where forest fires have not been common before. These forest fires have a direct impact on greenhouse gas emissions.
Forest and brush fires in Northern areas in 2020, especially near the polar region, have emitted more CO2 until the end of August than in the whole year of 2019 (181 megatons [mt]) according to the European Commission Copernicus Earth observation program, Copernicus Atmospheric Monitoring System (CAMS). The fires along the polar circle alone have emitted 244 mt CO2 into the atmosphere between January and August 2020. To bring that into context, in the year 2018, Austria had total emissions of 79 million tons (0.000079 mt) CO2 equivalent.
Forest fires in the tundra
The primary source of these increased CO2 emissions are the forest and brush fires in the tundra of Siberia and Alaska. One example are the forest fires in Yakutia in Northeast Russia where until August this year 395 mt CO2 were released from timber and soils. In 2019, forest fires in this area released 208 mt CO2 over the whole year. This area is almost inhabited, and no firefighter operations are taking place, which has led to million hectares of burned forest and tundra to date. To make things worse, fires have been smouldering below ground throughout the entire winter, causing the permafrost soil to melt and releasing methane from the ground. Methane is approximately 80 times more potent as a greenhouse gas than CO2. Methane emissions were included in the measurements mentioned above from CAMS as CO2 equivalents which could explain parts of the massive difference between 2019 and the first eight months of 2020. Between June and August 2020, 540 mt CO2 have been emitted over the whole of Russia from intense forest fires in different areas which broke the records of 2019 and 2003 according to CAMS.
According to the Alaska Fire Service, 2020 has seen 371 forest fires so far. These are caused by humans or by lightning strikes. Their size ranges from minor fires to 219 square kilometres. A large number of these fires is not actively contained and therefore will emit large amounts of GHG from trees and soil into the atmosphere.
Causes for forest fires
In large parts of the Northern hemisphere, the winter 2019/2020 was very mild and the spring exceptionally dry. Lightning or humans and their remains can easily ignite dead underbrush, grass and trees. This has created the perfect starting conditions for forest fires in Northern latitudes. The problem is enhanced by bark beetle epidemics which cause trees to dye. Dead conifer trees lose all their needles and are very dry but can keep standing in the forest for years unless removed by humans. In countries like Austria, these trees are removed within weeks or months. In large rural areas like British Columbia, Canada, the mountain pine beetle victims mostly are left in the woods. An ongoing outbreak of mountain pine beetle that started in British Columbia in the early 1990s has affected more than 18 million hectares of forest and spread into Alberta already, according to Natural Resources Canada. Dead and dry trees are an easy fuel for forest fires, as we all would know from firewood, which caused forest fires to become more intense and dangerous.
Natural fire cycle
Forest fires are a natural phenomenon and fires burn through forests regularly. In Northern latitudes, the fire season typically starts in May and reaches into September. In 2019 and 2020, fires began as early as March. This means that while the forest ecosystems are capable of handling fires, the fire cycle accelerates, and the increased amounts of GHG emissions can increase global warming.
A completely different case are the unprecedented forest fires in the Amazon region which are deliberately caused by humans with the purpose to create more land for agriculture, but this is a topic for another blog story.
Copyright cover photo USGS “Fire in a boreal forest in Alaska” taken by Scott Rupp.