- Forest fires are shifting north and intensifying, especially in high northern latitude areas such as Canada and Siberia, where fires are most sensitive to hotter, drier conditions.
- Climate change is fueling the expansion of forest fires in Earth’s high northern latitudes. Since 2001, emissions from fires in the north have nearly tripled.
- Fires in the north accelerate climate change by releasing more carbon to the atmosphere. Global carbon emissions from forest fires have increased by 60% over the past two decades. And the largest contributors were from Siberia and western North America.
By Matthew William Jones, University of East Anglia; Crystal A. Kolden, University of Idaho, and Stefan H Doerr, Swansea University
Forest fires are shifting north and intensifying
Fires have long been a natural part of forest ecosystems, but something is changing. Our new study shows that forest fires have become more widespread and severe amid global heating. This is particularly true in the high northern latitudes such as Canada and Siberia. Here, fires are most sensitive to hotter, drier conditions.
The implications of this are alarming. And not just for the ecosystems affected or the cities engulfed by smoke downwind, but for the planet’s ability to store carbon and regulate the climate. The trend we discovered contrasts with declining fire extent in savannah grasslands, which may reflect the expansion of farming and changing rainfall patterns.
We established the leading causes of forest fires in different parts of the world using an AI algorithm. It grouped forest regions into distinct zones with similar fire patterns and underlying causes. And it uncovered the worrying extent to which climate change is fueling the expansion of forest fires in Earth’s high northern latitudes.
More fires in ‘extratropical’ forests
Since 2001, emissions from fires in forests outside of the tropics – like parts of the boreal forest in the far north of North America and Eurasia – have nearly tripled. This rise is largely the result of hotter, drier weather occurring more frequently, combined with forests growing more efficiently in places where the cold once stunted their growth.
Climate change is creating ideal conditions for larger, more intense fires. And those fires then accelerate climate change in turn by releasing more carbon to the atmosphere. In fact, we found global carbon emissions from forest fires have increased by 60% over the past two decades. The largest contributions come from fires in Siberia and western North America.
Northern fires are different
This trend shifts the focus of forest fire emissions from tropical forests, where fires set to make room for farmland have long contributed carbon to the atmosphere. Conservation policies have reduced deforestation rates since the early 2000s in some regions, particularly Amazonia. By contrast, increasing fires in northern forests, such as the taiga – the forest of the cold sub-arctic region – are driven by changing climate conditions and generally started by lightning. And that makes them harder to prevent.
Not only is the area affected by fires expanding, but the fires themselves are growing more severe and releasing more carbon, according to our new findings. This corresponds with an earlier study that found fires are doing more damage to ecosystems globally than in the past. Fires are burning through drier and more flammable vegetation as global temperatures rise and droughts become more frequent.
In northern forests, more severe fires can burn deep into the soil and release carbon that has accumulated over centuries. Forests can remain net carbon emitters for decades after burning. And the more severe fires become, the longer it takes forests to rebound and recapture carbon lost during the fire.
What does the shift in forest fires mean for the planet?
The steep rise in fire emissions from forests outside the tropics is a clear signal that the capacity of Earth’s forest to store carbon is at increasing risk.
Forests, particularly in northern regions, absorb and store CO2 from the atmosphere. But as fires expand and become more severe, these vital carbon sinks are weakened. This undermines the global effort to tackle climate change as forests offset emissions from human activities that burn fossil fuels.
Forest fires were long considered part of the natural carbon cycle. But increasingly human-caused climate change is driving them. Yet international reporting standards don’t differentiate between “natural” levels of forest fire emissions and the higher emissions we’re seeing due to climate change.
This allows excess fire emissions caused by humans to fall outside the scope of national carbon budgets tracked by organizations like the United Nations. Gaps emerge between the carbon emissions we think we’re managing and the actual amount that’s passing between the land and the atmosphere.
What drives fires in different regions varies, so addressing this growing threat requires tailored approaches. Outside of the tropics, proactive forest management is essential. Carefully managed fires and thinning out vegetation can mean fires ultimately cause less damage when they do ignite. Monitoring vegetation growth, alongside fire-favorable weather conditions, can help identify and prioritize areas for intervention.
In tropical forests, reducing ignitions (especially during droughts) and preventing forest fragmentation is key to protecting these ecosystems and their carbon stocks. This may help prevent the more extreme fires that turn tropical forests from carbon sinks into sources.
Increasing fires are a symptom of climate change
Limiting the burning of fossil fuels is central to minimizing future fire risk. Without drastic cuts to greenhouse gas emissions, more severe and widespread forest fires are likely, with increasing damage to ecosystems, biodiversity and the climate.
Our study also highlighted the importance of updating international reporting standards on carbon emissions. As forest fires become more closely linked to human-driven climate change, it’s crucial that officials include fire emissions in national carbon budgets to provide a more accurate picture of the planet’s carbon fluxes.
There is also a risk of overestimating how much carbon is stored by reforesting areas, especially outside the tropics. Many carbon offset schemes rely on planting new trees or delaying the harvest of existing ones to absorb CO2. But if the growing threat of forest fires isn’t properly accounted for, these projects could fail to deliver the carbon savings they promise.
Forest fires are no longer just a natural occurrence. As they shift north and intensify, these fires are a clear symptom of human-caused climate change.
It’s essential to recognize the growing role that fires play in the carbon cycle. By doing so, we can better manage fire risks, safeguard forests and ensure a more resilient future for the planet.
Matthew William Jones, University of East Anglia; Crystal A. Kolden, University of Idaho, and Stefan H Doerr, Swansea University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Bottom line: Forest fires are shifting north and intensifying, especially in the high northern latitude areas such as Canada and Siberia, where fires are most sensitive to hotter, drier conditions. Here’s what that means for the planet.
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