Carbon dioxide (CO2) emitted from forest fires grew by 60 per cent across all forests globally since 2001, a new study has revealed.
The fire emissions spanning boreal forests in Eurasia and North America almost tripled between 2001 and 2023, the study published in Science has stated. The analysis also revealed that apart from tropical and subtropical forest areas, extratropical forest fire carbon emissions from areas located outside the tropics have increased significantly due to climate change.
The geographical shift caused an increase in the carbon combustion rate of forest fires by 47 per cent across all forest ecoregions. The observation reflects higher fuel consumption per unit of forest burned area.
The findings also indicate that the above factors caused a shift from savannah and grasslands to forests becoming major sources of fire emissions.
Stefan Doerr, director of the Centre for Wildfire Research at Swansea university, UK, highlighted the worrying increase in the extent of forest wildfires and their severity in a statement. He said, “The carbon combustion rate, a measure of fire severity based on how much carbon is emitted per unit of area burned, increased by almost 50 per cent across forests globally between 2001 and 2023.”
“Extreme examples of carbon combustion per unit area have been recorded during recent extreme wildfire episodes and tied to extremes in fire-favourable weather, whereas our findings support a more general trend toward increases in fuel consumption in forests,” the study said.
The study used machine learning to look globally at the difference between forest and non-forest fires by segregating them into 12 forest ecoregion pyromes.
‘Pyromes’ are defined as regions where forest fire patterns are affected by similar environmental, human, and climatic factors, thereby revealing the elements pushing recent increases in forest fires.
Grouping forests into pyromes enabled the authors to isolate the impacts of climate change, apart from other influencing drivers such as land use and vegetation.
Noting the massive forest fires recorded in Australia, Eurasia, North America and Canada between 2019 and 2023, the authors stated that increased fire incidences, especially extreme forest fires make the functioning and resilience of some forests vulnerable. Their ecosystem services, including carbon storage and capture, are threatened as vegetation and organic soils can take decades or centuries to recover following the events, they observed.
The study further stated that anthropogenic climate change is one of the drivers of forest fires, resulting in more frequent and severe droughts causing fire favourable weather, known as ‘fire weather’.
Increased hot and dry conditions produced extreme long periods of low fuel moisture, favouring wildfire conditions in ecosystems having rich stocks of vegetation biomass. Increased lightning frequency was also found to be a major reason for triggering forest fires, especially in forests located on high altitudes.
Such conditions have caused a change in the forest fire regime in some forest areas. For instance, destabilisation of forest carbon stocks is progressing in temperate broadleaf/mixed; temperate coniferous; boreal; mediterranean; (Sub)tropical dry broadleaf and (Sub)tropical moist broadleaf forests.
The scientists express concern that as carbon emissions from forest fires grow, it would impact the relevance of carbon accounting, including the greenhouse gas (GHG) inventories presented to the United Nations.
“For example, carbon emissions from wildfires in Canada during 2023 alone are likely to have overturned a significant portion of the carbon sink to Canadian forests that accumulated over the prior decade,” it said.
It said the wildfires in Canada have anthropogenic influence. But they continue to be considered as natural disturbances in Canada’s national emissions inventory and thus their influence is largely omitted from UN records.
Lead author, Matthew Jones from Tyndall Centre for Climate Change Research of the University of East Anglia, (UEA), “Our findings underscore the urgency for policymakers and environmental agencies to prioritise climate mitigation and proactive forest management strategies to protect these critical ecosystems from the accelerating threat of wildfires.”