Global CO₂ emissions from wildfires increased by 60% since 2001, study finds

A major new study finds that carbon dioxide (CO₂) emissions from wildfires have increased 60% globally since 2001 and nearly tripled in some of the most climate-sensitive northern boreal forests.

The study, led by the University of East Anglia (UEA) and published in Sciencegrouped regions of the world into “pyromes” – regions where wildfires are affected by similar environmental, human and climatic controls – revealing the key factors behind the recent increase in wildfire activity. forest.

This is one of the first studies to globally examine the differences between wildfires and non-forest fires, and shows that in one of the largest pyromes, which spans forests boreal regions of Eurasia and North America, emissions from fires almost tripled between 2001 and 2023.

Significant increases have been observed more widely in extratropical forests and amount to an additional half a billion tonnes of CO.₂ per year, with the epicenter of emissions moving from tropical forests to extratropical areas.

The increase in emissions was linked to an increase in favorable fire weather conditions, such as the hot and dry conditions seen during heat waves and droughts, as well as an increase in forest growth rates, creating more plant fuels. Both trends are driven by rapid warming in high northern latitudes, which is occurring twice as fast as the global average.

The study reveals a worrying increase not only in the scale of wildfires over the past two decades, but also in their severity. The carbon burn rate, a measure of fire severity based on the amount of carbon emitted per unit of area burned, increased by almost 50% in the world’s forests between 2001 and 2023.

The work involved an international team of scientists – from the UK, Netherlands, US, Brazil and Spain – who warn that the expansion of wildfires can only be avoided if The main causes of climate change, such as fossil fuel emissions, are addressed. addressed.

Lead author Dr Matthew Jones, from the Tyndall Center for Climate Change Research at UEA, said: “The increase in the extent and severity of wildfires has led to a dramatic increase in the amount of carbon emitted by wildfires globally. In the global geography, fires are also underway, and they are mainly explained by the increasing impacts of climate change on the planet’s boreal forests.

“To protect critical forest ecosystems from the growing threat of wildfires, we must contain global warming and this highlights why rapid progress towards net zero emissions is so vital.”

Threats to carbon storage

Forests are globally important for storing carbon, with their growth helping to remove CO₂ of the atmosphere and reduce the rate of global warming.

They also play a crucial role in meeting international climate goals, with reforestation and afforestation programs implemented to remove carbon from the atmosphere and offset human CO.₂ emissions from hard-to-reduce sectors such as aviation and certain industries.

The success of these projects relies on the permanent storage of carbon in forests, which wildfires threaten. Extratropical fires already emit half a billion tonnes of additional CO₂ more than twenty years ago, and the long-term effect depends on how the forests recover. More widespread and severe wildfires are a sign that emissions are now out of balance with the carbon captured by fire recovery.

Dr Jones, an independent NERC researcher, said: “The strong trend towards increased emissions from extratropical wildfires is a warning of the growing vulnerability of forests and poses a significant challenge to global goals to combat climate change. .

“We know that forests recover poorly after the most severe fires, so there is enormous interest in how the observed increase in fire severity will influence carbon storage in forests over the coming decades . This requires our special attention.”

Escalating wildfire impacts hidden until now

Importantly, the increase in emissions from wildfires contrasts with the reduction in fires in the planet’s tropical savannahs over the same period. Previous studies have shown that, since 2001, the area burned by all fires (forest and non-forest) has decreased by a quarter globally, mainly because of this.

The latest findings are important because wildfires burn more severely and release greater amounts of harmful smoke into the atmosphere than savannah fires, posing major threats to people living near the fires and to communities more remote areas exposed to poor air quality caused by smoke.

The authors say the study debunks the narrative that the decrease in overall annual area burned by fires globally means a decrease in the impact of wildfires.

“Until now, the reduction of fires in already fire-prone savannahs and grasslands has masked the increase in the extent and severity of wildfires, which have enormous consequences for society and environment,” Dr Jones said. “Our work shows that fires are increasingly occurring where we don’t want them: in forests, where they pose the greatest threat to people and to vital carbon stores.”

Managing forest fires

Machine learning has been key to unlocking new observations about the changing global geography of wildfires. It was used to group the world’s forest ecoregions into 12 distinct pyromes, allowing researchers to isolate the effects of climate change from other influencing factors such as land use.

This knowledge also reveals new insights into the most effective strategies for mitigating wildfires and protecting forests. Dr Jones said: “Substantial funding is needed to support strategic forest management, stakeholder engagement and public education programs, all of which represent a significant shift in a country’s fire management strategy. largely reactive strategy to an increasingly proactive strategy.

“For example, priority areas for forest management and firebreaks should be defined based on proactive monitoring of forest productivity, particularly in extratropical areas. Managing fuel loads in places where they could present the greatest danger during favorable fire weather is a key priority to limit the severity and impact of fires when they do occur.