Climate Change, Wildfires, and Health: A Burning Crisis in the Anthropocene
Christopher Nial
Watching How Climate will Change Health @FINNPartners | Rotarian | dog dad | whack-a-mole expert | keen listener | defiant optimist despite evidence to contrary
Climate change is altering weather patterns and dramatically intensifying global fire regimes. Wildfires rage across previously untouched regions or are only seasonally affected, leaving a trail of destruction far beyond physical landscapes. Recent studies illustrate that climate change is now a dominant force in global fire dynamics, with grave consequences for human health. Wildfires contribute significantly to air pollution, especially by increasing fine particulate matter (PM2.5), exacerbating respiratory and cardiovascular illnesses. "Our results highlight the importance of immediate, drastic and sustained GHG emission reductions and landscape and fire management strategies to stabilise fire impacts on lives, livelihoods and ecosystems".
Global Fire Regimes and Climate Change
Recent research published in Nature Climate Change emphasises the growing contribution of climate change to the intensity and frequency of wildfires. Using global fire models, the study attributes a 15.8% increase in the global burned area from 2003 to 2019 to climate change. This rise is especially evident in regions such as central Australia, northern South America, and parts of North America and Siberia, where climate-driven factors such as higher temperatures and increased fuel dryness have accelerated fire spread. "In northern Australia, southeastern South America, and western North America, burned area increased by over 14% due to climate change".
However, in contrast to this increase, human land-use practices, including fire suppression, have mitigated the overall burned area in some regions. The study notes, "Socio-economic dynamics, such as land-use changes, decreased burned area by 19.1% globally in the present-day period compared to the early-industrial period". But as climate change accelerates, the balance shifts in favour of more frequent, intense fires.
Health Impacts of Fire-Induced Air Pollution
One of the most alarming aspects of increasing wildfires is the surge in PM2.5 concentrations, which harms human health. According to another study in Nature Climate Change, fire-related PM2.5 mortality has risen dramatically over the last six decades. The study reports a jump in global deaths attributable to fire-induced PM2.5 from 669 annual deaths in the 1960s to over 12,500 by the 2010s, with climate change responsible for an increasing proportion of these deaths (from 1.2% to 12.8% during the same period).
The health risks of fire smoke, particularly PM2.5, are well-documented. These microscopic particles penetrate the lungs, causing or exacerbating asthma, chronic obstructive pulmonary disease (COPD), and cardiovascular problems. "Fine particulate matter (PM2.5) is a major environmental risk... contributing to 4.1–8.9 million annual global deaths," the article highlights the profound health impacts these particles have worldwide.
Regions most affected by this surge in PM2.5 mortality include South America, Europe, and Australia, where climate change has intensified fire conditions. The study found that in Southern Hemisphere South America (SHSA), "fire mortality increased by 71% in the 2010s compared to the 1960s", driven by the dual effects of rising temperatures and reduced humidity. Australia saw similar trends, with over 20% of its fire-related mortality attributable to climate change since the 1970s.
Case Study 1: Canadian Wildfires in 2023
In 2023, Canada experienced one of its worst wildfire seasons, with blazes ravaging millions of hectares of forest across Alberta, Quebec, and other provinces. By mid-summer, the fires had emitted unprecedented volumes of smoke, which travelled southwards, blanketing large swathes of the United States in a thick, toxic haze. One of the most affected cities was New York, where the air quality index (AQI) reached dangerous levels in June 2023, forcing residents to stay indoors.
These fires were exacerbated by the effects of climate change, particularly the increasing temperatures and prolonged drought conditions that made forests more flammable. "The fires in Canada align with research showing an increasing trend in fire activity due to climate change, especially in boreal forests, where rising temperatures have significantly dried out vegetation, creating ideal conditions for mega-fires".
As the smoke travelled, millions in the northeastern US were exposed to PM2.5 concentrations many times higher than recommended health limits. "The record-breaking forest fires in Canada in 2023 impacted the United States and Canada, raising emergency department visits". This case highlights the transboundary nature of fire pollution and the urgent need for coordinated fire management and public health response strategies between nations.
Case Study 2: Wildfires in Portugal
Portugal, known for its Mediterranean climate, has always had a wildfire season, but in recent years, the intensity and scale of these fires have grown due to climate change. The summer of 2017 was particularly catastrophic when wildfires, fuelled by heatwaves and dry conditions, ravaged the country. One of the most devastating fires occurred in the Pedrógão Grande region, where over 60 people were killed, many trapped in their cars while attempting to flee.
"Southern Europe, including Portugal, has seen an increase in fire activity, driven by hotter and drier conditions". In Portugal, increasing temperatures and declining humidity levels have created a dangerous fire-prone environment. The fires in 2017 caused widespread destruction of forests and agricultural land, and the smoke severely impacted air quality, contributing to spikes in respiratory and cardiovascular issues in the affected regions.
Portugal's wildfires are not just an environmental crisis but a public health one. "The ACC (Attribution to Climate Change) of fire mortality in southern Europe increased from 10% in the 1990s to 39% in the 2010s, largely due to increasing air temperature and decreasing humidity". The fires also highlight the vulnerability of rural populations, where firefighting resources are scarce and emergency responses are slower. The aftermath has led Portugal to adopt more aggressive fire prevention and forest management policies, but the rising temperatures continue to pose a persistent threat.
The Role of Fire Models
The integration of advanced fire-vegetation models has allowed scientists to estimate how fire dynamics have evolved under the influence of climate change. Using models such as CLASSIC, SSiB4, and JULES, researchers could simulate fire spread, emissions, and health impacts over the past 60 years. These simulations demonstrate "an increase in excess annual mortality from fire-related PM2.5 from 669 deaths in the 1960s to 12,566 in the 2010s," directly attributable to climate change.
Such models have improved the precision of these projections, especially in understanding regional differences in fire dynamics. "The highest agreement between models was found in fire-prone areas like southern Australia, South America, and Siberia", highlighting the particular vulnerability of these regions to future fire risks.
Regional Variations and Public Health Crisis
While some regions are experiencing heightened fire risk and related mortality, others have seen a decrease due to various factors, including relative humidity and land-use changes. However, where fires do occur, their impacts are severe. The Amazon basin, for example, is seeing increasingly intense fire seasons, which are projected to worsen as climate change progresses. "The southern part of the Amazon basin experienced higher fire emissions under climate change, although its impact on PM2.5 exposure was negligible due to the wind patterns that transported smoke southward".
Europe has also seen a marked increase in fire mortality linked to climate change, particularly in southern Europe. According to the study, "fire mortality in southern Europe rose sharply from 10% in the 1990s to 39% in the 2010s, driven by hotter and drier conditions". This is consistent with observations of increasingly intense fire seasons in countries like Spain, Greece, and Portugal.
Policy and Adaptation Strategies
The rising frequency and intensity of wildfires, compounded by their devastating health impacts, demands urgent policy action. Governments must adopt more effective fire management strategies beyond suppression tactics. Instead, they should focus on prevention, regional landscape management, and strengthening healthcare systems to cope with the increased burden of fire-induced air pollution.
Some policy recommendations from the research include:
As the planet continues to warm, wildfires will become an even more significant force, reshaping ecosystems and threatening human health on an unprecedented scale. The consequences of inaction are stark: more frequent and intense fires, rising mortality rates, and ecosystem collapse. To mitigate these risks, bold climate action and comprehensive fire management strategies are essential. Without immediate interventions, the combined impacts of fire and climate change will continue to exact an ever-growing toll on human lives and the planet.