Wildfires are an essential component of many natural ecosystems. However, climate change is creating conditions that cause fires to burn longer and hotter, threatening the environment and public health.
Wildfires have shaped native landscapes for thousands of years. Fire is woven into the ecological history of native grasslands, oak prairies, longleaf pine forests, and ecosystems all over the world. Before settler colonialism, Indigenous people in North America used fire as a tool to care for the land, promoting new growth and restoring soil fertility. Although the beneficial roles of fire have been obscured by the erasure of Indigenous land stewardship practices, fire has always had an important place in our environment.
While wildfires have been burning naturally for millennia, their scale, frequency, and intensity have grown to dangerous new levels in recent years. Fire regimes are shifting, and the increasingly destructive nature of fires is now outpacing the sustainable growth they once helped promote. Fire seasons are becoming longer and more destructive, and a growing body of evidence points to climate change as the driving force behind this shift. How are fire and climate related, and what do these connections mean for people living in a more fire-prone world?
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How Climate Drives Wildfire
Fire requires three ingredients to ignite: fuel, oxygen, and heat. Climate change increases the likelihood of all three. Intense periods of drought, rising temperatures, and dry soils brought about by changing weather patterns produce an abundance of readily ignitable fuels (the organic material consumed by wildfires including grasses, shrubs, and trees). These conditions create an ideal environment for fire to thrive, turning some ecosystems into tinderboxes.
“With climate change, fuels and the forests that we really care about are ending up drier for a longer part of the summer,” said Dr. Susan Prichard, a forest ecologist at the University of Washington who specialises in wildfire ecology. “Increased winds [oxygen] and lightning activity [heat/ignition source] are playing a huge role too.”
In an interview with Earth.org, she helped draw connections between changing climates and changing fire regimes.
One of climate change’s many consequences is an increase in severe weather events, like heatwaves and powerful storms. In some areas, this translates to long periods of drought punctuated by intense bursts of precipitation – like the record-setting snowfall observed in northern California this year.
The idea that fuels are drying out at a dangerous rate may seem at odds with the fact that some areas are seeing an uptick in heavy precipitation. How could wetter winters contribute to more active fire seasons?
“We could have a really good snow year like we did in the West,” explained Dr. Prichard. “But if we have record-setting warm temperatures in the early spring, like we did, snow melts so quickly. Then those fuels dry out and are ready to burn pretty early in the season.”
In some environments, heavy precipitation events can boost plant growth – particularly in grass-dominated ecosystems – and lead to a stockpile of fuels. Researchers at NASA recently discovered that wet winters may result in a larger number of small wildfires the following fire season.
Changes in the frequency and intensity of fires also contributes to a destructive climate feedback loop. As large swaths of forest are consumed by fire, the carbon that was sequestered in trees and soil is released back into the atmosphere, perpetuating a destructive cycle.
Smoke on the Horizon: What Comes Next?
Like rising seas and record breaking temperatures, today’s fires are proof that the consequences of climate change are not problems for a distant future – they are happening now. People who have not typically had to worry about fires are now experiencing the devastating impacts first-hand, like the millions of New Yorkers who recently stepped outside to find their city shrouded in orange smoke. Under current conditions, this eerie scene may become more commonplace.
The National Interagency Fire Center’s predicative report anticipates above normal fire activity for several parts of the US this year, including the Pacific Northwest, the Great Lakes Region, and New England. The World Meteorological Organization (WMO) also predicts increased fire activity for parts of the Arctic, central Europe, Indonesia, and the Brazilian Amazon. One report from the United Nations Environment Programme (UNEP) warns that extreme wildfires are not only here to stay – they will likely get worse. Even with a hypothetical reduction in greenhouse gas emissions, their research shows that wildfires would still increase 50% by the year 2100.
How Wildfires Impact Human Health
The impacts of severe wildfires are not limited to communities at the edges of forests or historically fire-prone areas. As wildfires move across the landscape, they pump carbon monoxide, nitrogen oxides, and a variety of carcinogenic compounds into the air. These compounds can travel long distances, riding the wind into highly populated areas hundreds of miles away.
Exposure to wildfire smoke may worsen preexisting respiratory conditions like asthma, exacerbate cardiovascular problems, and even cause birth complications. Wildfires weigh heavily on mental health, stirring up fear, anxiety, and stress for those forced to evacuate (or alternatively, those who cannot). Some groups are at greater risk of experiencing negative health effects than others, making wildfires and their associated health impacts an issue of environmental justice. One study found that between 2017 and 2021, Americans on average were exposed to 350% more wildfire smoke than previous years. For communities with more people of colour and non-English speakers, this number was closer to 450%.
“There are these compound impacts of wildfire that are really concerning … certain groups like low-income communities and people of colour already experience disproportionate health concerns like asthma,” said Dr. Prichard. “Wildfires can make this even worse.”
Like so many issues related to climate change, restoring healthy fire regimes is a matter of reducing emissions in the atmosphere. While it would be an enormous feat, it is still possible to avoid some of the worst impacts of climate change, including devastating fire seasons year after year. By shifting towards clean energy and severing the climate-wildfire feedback loop, we can minimise further warming and potentially undo some of the conditions that allow destructive wildfires to thrive. Supporting policies that promote responsible forest management and push back against unsustainable practices like deforestation may help protect ecosystems threatened by fire.
Despite our best personal intentions, a more fiery future is almost certain. By understanding connections between climate, wildfire, and human health, we can work to educate others and provide better access to care for those at risk of health impacts – especially those at a disproportionate risk.
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