Fires in the boreal forest, the green ring that surrounds the Arctic, have been on the rise for two decades, with a high point in 2021, the year in which these phenomena emitted the most CO₂ since records have been recorded, warns a recently published study.
These fires are fueled by drier and hotter conditions caused by climate change, and by causing the release of greenhouse gases contribute to global warming, in a vicious cycle.
Found mainly in Siberia, northern Canada and Alaska, the boreal forest is the world's largest wilderness area, but it has so far not received the same attention as the tropical rainforest, the study highlights.
Fires in boreal forests normally account for 10% of global carbon dioxide (CO₂) emissions from fires, they contributed 23% in 2021, marking a new annual record.
This is reflected in a study carried out by 18 researchers from institutions in Germany, Australia, China, Cyprus, Spain, the United States, France or the Netherlands, and published in the journal 'Science'. In the list of authors is Emilio Chuvieco, from the University of Alcalá de Henares (Madrid).
“The boreal forests could be a carbon time bomb, and the recent increases in emissions from wildfires that we see worry me because the clock is ticking,” says Steven Davis of the University of California.
Extreme wildfires, which affect the climate through the carbon dioxide they emit, have become more common. In the tropical forests they have received notable attention for their emissions, while those in the boreal forests (in the north of the planet) have attracted much less attention, despite the fact that it is the largest terrestrial biome in the world and the fires in these Regions release 10 to 20 times more carbon per unit area burned than other ecosystems.
Satellite-based approaches to track CO₂ emissions from fires may miss those from small fires. Also, carbon dioxide is difficult to identify in fires and can remain in the atmosphere for hundreds of years, meaning that background CO₂ concentrations are quite high compared to those released by small forest fires.
To better analyze emissions from fires, and in the boreal regions in particular, the researchers used a new approach to indirectly track carbon dioxide emissions from fires.
The authors used satellite data from Mopitt (Tropospheric Pollution Measurements Instrument), the satellite instrument with the longest continuous time series of carbon dioxide measurements to date, to calculate weekly global carbon monoxide emissions. and carbon dioxide from fires in the boreal regions through an atmospheric inversion system approach.
This revealed a two-decade trend of expanding summer fires in boreal forests since 2000 and record emissions in 2021, coinciding with a severe heatwave, drought, and high water deficit in those regions that year.
