How high-latitude peat and forest fires could shape the future of Earth’s climate

Understanding how wildfires influence our planet’s climate is a daunting challenge. Although fire occurs nearly everywhere on Earth and has always been present, it is still one of the least understood components of the Earth system. Recently, unprecedented fire activity has been observed in boreal (northern) and Arctic regions, which has drawn the scientific community’s attention to areas whose role in the future of our planet remains a mystery. Climate change likely has a major role in this alarming trend. However, high-latitude wildfires are not just a symptom of climate change; they are an accelerating force that could shape the future of our climate in ways that we are currently incapable of predicting.

The rising threat of northern fires

As global temperatures rise, wildfires are advancing further north and reaching into the Arctic. Canada, Alaska, Siberia, Scandinavia and even Greenland, all in northern high-latitude regions, have recently experienced some of the most intense and prolonged wildfire seasons on record. With climate change occurring more rapidly in these areas, the future of northern fires appears even grimmer.

Apart from typical forest fires that consume surface vegetation, many high-latitude fires burn through peat, the dense, carbon-rich layers of partially decayed organic material. Despite covering only 3% of the terrestrial surface, peatlands are one of the world’s most important carbon storage environments, containing around 25% of the carbon existing in the Earth’s soils.

Climate warming, which is even faster at high northern latitudes due to polar amplification – the phenomenon of greater climate change near the poles compared to the rest of the hemisphere or globe – is increasing the vulnerability of these ecosystems to fire, with potentially severe implications for the global climate. When peatlands ignite, they release massive amounts of “fossil carbon” that have been locked away for centuries or even millennia. The largest and most persistent fires on Earth, peat fires can smoulder for extended periods, are difficult to extinguish and can continue burning underground throughout the winter, only to reignite on the surface in spring. They have recently been described as “zombie” fires.

Warmer and drier conditions driven by climate change, apart from making boreal forests more flammable, are expected to intensify and increase the frequency of peat fires, potentially transforming peatlands from carbon sinks into net sources of greenhouse gas emissions. Such a shift could trigger a feedback loop, meaning that a warming climate will cause more carbon emissions, which in turn will accelerate climate change.

Air pollution and weather patterns

Wildfires release large quantities of smoke particles (aerosols) into the atmosphere, contributing significantly to both local and widespread air quality degradation. These particles are harmful to human health and can cause serious respiratory and cardiovascular problems, while prolonged exposure may lead to smoke-induced stress, hospitalizations and increased mortality. Wildfires can also cause mental health strains associated with evacuations, loss of homes, livelihoods and lives.

Beyond their long-term effects on climate, wildfire emissions can also influence weather patterns in more short-term ways via their impacts on atmospheric pollution levels. Smoke particles interact with sunlight and cloud formation processes, subsequently affecting temperatures, wind patterns and rainfall.

For example, our recent study on the large-scale atmospheric impacts of the 2023 Canadian wildfires, which we presented at the European Geosciences Union general assembly this spring, demonstrated that wildfire aerosols led to a surface air temperature decrease that expanded to the entire northern hemisphere. The cooling was particularly pronounced over Canada (up to -5.5°C in August), where the emissions were located, but was also significant over remote areas such as Eastern Europe and even Siberia (up to around -2.5°C in July). The average hemispheric temperature anomaly we calculated (close to -1°C) highlights the potential for large regional emissions from wildfires to perturb weather conditions for weeks across a whole hemisphere, with profound implications for forecasting. Unreliable weather forecasts can disrupt daily activities and pose risks to public safety, especially during extreme events such as heatwaves or storms. They also have serious consequences for industries such as farming, fishing and transport, where planning depends heavily on accurate, timely predictions.

Peat fires and the climate puzzle

While incorporating peatland fire feedbacks into Earth System Models (ESMs) is essential for accurate climate projections, most existing models lack a representation of peat fires. Understanding the smouldering behaviour of organic soils when they burn, their ignition probability, and how these processes can be represented at a global scale is of utmost importance. Recent research efforts are focusing on bridging this knowledge gap. For example, at the Technical University of Crete, we are collaborating with the Hazelab research group at Imperial College London and the Leverhulme Centre for Wildfires, Environment and Society to perform field research and cutting-edge experiments) on peat smouldering, with the aim of shedding light on the complex mechanisms of peat fires.

Integrating these lab results into ESMs will enable game-changing fire emission modelling, which holds potential for groundbreaking outcomes when it comes to our skill level for predicting the future of the Earth’s climate. By quantifying how the present-day atmosphere is influenced by fire emissions from boreal forests and peatlands, we can enhance the quality of projections of global temperature rise. This integration will also sharpen forecasts of regional climate impacts driven by fire-related aerosols, such as changes in rainfall patterns or accelerated Arctic ice melt.

Tackling the challenge of northern fires

Undoubtedly, we have entered an era of more frequent megafires – wildfires of extreme size, intensity, duration or impacts – with catastrophic consequences. Recent megafire events at boreal and Arctic regions unveil the dramatic change in wildfire patterns in northern high latitudes, which is a matter that demands urgent attention and action.

As the planet continues to warm, high-latitude fires are expected to help shape the future of our planet. Massive wildfire events, such as those in Canada in 2023, not only burned millions of hectares but also forced hundreds of thousands of people to evacuate their homes. Unprecedented amounts of smoke blanketed parts of North America in hazardous air, prompting school closures and health warnings, and obliging citizens to remain indoors for days. Events like this reflect a growing trend. They underscore why advancing research to better understand and predict the dynamics of northern peat and forest fires, and to mitigate their climate impacts, is not only a scientific imperative but also a moral responsibility.

This article is also published on The Conversation. illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.