Forest fires are becoming increasingly more common outside the tropics, raising concerns about the future ability of trees to absorb carbon dioxide under climate change, a study has warned.
Carbon emissions from forest fires have surged globally by 60 per cent between 2001 and 2023, and almost tripled in some of the most vulnerable northern boreal forests, which cover areas including Siberia, Scandinavia, Canada and Alaska.
The blazes, which are being fuelled by global warming, have resulted in the release of an additional half a billion tonnes of carbon a year.
Forests are major carbon sinks, which means they absorb more carbon dioxide than they release, offsetting the impact of global warming. When they burn, the carbon stored in them is released, turning them into a carbon dioxide source.
Carbon is drawn back out again when the vegetation regrows. But more widespread and severe forest fires are a sign that emissions are now out of balance with the carbon captured by post-fire recovery, say researchers.
Wildfires in Canada – in pictures
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The McDougall Creek wildfire burns on the mountainside above a lakefront home in West Kelowna, British Columbia. All photos: The Canadian Press / AP -
Thousands have been forced to flee in western Canada due to wildfires -
Those evacuating have driven hundreds of kilometers to safety or waited in long queues for emergency flights, as the worst fire season on record in Canada showed no signs of easing -
Two motorcyclists stop to view the McDougall Creek wildfire -
Hundreds of wildfires prompted emergency evacuations in western Canada -
Residents who are unable to drive to safety have been advised to register for flights taking off from nearby areas -
Ingraham Trail, in Dettah, Kam Lake, Grace Lake and Engle Business District face the greatest risk from the wildfires in the Northwest Territories -
The McDougall Creek wildfire -
Hundreds of people have been evacuated by plane from remote areas -
The McDougall Creek wildfire burns on the mountainside -
More than 200 fires have already burnt through parts of the Northwest Territories in Canada -
Fires tear through a mountainside in British Columbia -
Canadian wildfires have burnt more than 10 million hectares in 2023 -
The McDougall Creek wildfire -
The National Weather Service has said smoke from Canada's fires will once again cross into the US
“Increases in both the extent and severity of forest fires have led to a dramatic rise in the amount of carbon emitted by forest fires globally,” said Lead author Dr Matthew Jones, of the Tyndall Centre for Climate Change Research at the University of East Anglia, which led the research.
“Startling shifts in the global geography of fires are also under way, and they are primarily explained by the growing impacts of climate change in the world’s boreal forests.
“To protect critical forest ecosystems from the accelerating threat of wildfires, we must keep global warming at bay and this underscores why it is so vital to make rapid progress towards net zero emissions.”
The study found the fires are also becoming more severe, with the carbon combustion rate, a measure of carbon dioxide per unit of area burnt, rising by almost 50 per cent across forests globally between 2001 and 2023. The long-term effect depends on how forests recover, say researchers.
The researchers warned further expansion of forest fires can only be averted if the primary causes of climate change, such as fossil fuel emissions, are tackled.
“The steep trend towards greater extratropical forest fire emissions is a warning of the growing vulnerability of forests and it poses a significant challenge for global targets to tackle climate change,” said Dr Jones.
“We know that forests rebound poorly after the most severe fires, so there is huge interest in how the observed increases in fire severity will influence carbon storage in forests over the coming decades. This demands our close attention.”
The rise in carbon dioxide emissions from forest fires contrasts with the reduced burning of the world’s tropical savannahs during the same period.
“Until now, reduced burning in the already fire-prone savannahs and grasslands has masked increases in forest fire extent and severity that are hugely consequential for society and the environment,” said Dr Jones.
“Our work shows that fires are increasingly happening where we don’t want them to – in forests, where they present the greatest threat to people and to vital carbon stores.”
Last month it was revealed that Brazil’s Amazon and Pantanal wetland regions have experienced their worst wildfires in almost two decades. About 2.4 million hectares of forests, fields and pastures in the Amazon burnt between June and August.
