Deaths from climate change-linked wildfires are on the rise globally

The risk of wildfires is rising, and it’s only likely to get worse.

Two new studies published in Nature Climate Change have shown that rising temperatures are influencing the increase in wildfires and the resulting public health impacts around the world.

The first, looking at the patterns of wildfires, suggests that almost 16% more land burned between 2003 and 2019 because of climate change. This is the equivalent of the country of South Africa being entirely lost to fire.

As numbers of fires increased, so did the amount of air pollution. The researchers of the second study estimate that over 10,000 more people died every year in the 2010s than they did in the 1960s as a result of particulates from wildfire smoke.

With levels of greenhouse gases continuing to rise, and climate records being broken almost annually, the researchers have warned that wildfires will continue to become more common in the coming decades.

“The rate at which climate change impacts on wildfires is increasing every year,” said Professor Wim Thiery, a co-author of the study. “As we witness increasingly destructive fire seasons worldwide, it is essential that we not only adapt our policies to better manage fires, but also address the underlying causes of climate change.”

Climate-driven wildfires burning more land

While it might seem obvious that higher temperatures lead to more wildfires, it’s not actually that straightforward. Fires are influenced by a variety of different factors that are difficult to simulate, including weather patterns, land use and vegetation.

To try and account for this, the researchers compared two models of that past 20 years – one based on reality, and the other on a world where climate change didn’t happen. The latter is known as a counterfactual simulation.

Seppe Lampe, a PhD student who was one of the lead authors of the research, explains how this works.

“The factual and counterfactual models use the same data, but in the counterfactual one we fix levels of carbon dioxide at the level they would have been in 1901 and remove the impact climate has on the weather,” he says.

“This means that while a warm day in London will still be a warm day in both models, the one based on reality will be slightly warmer because of the impact of climate change. This means that any differences in the burned area between both simulations are the result of changes in carbon dioxide.”

The scientists found that the influence of climate change on wildfires is growing significantly. Some of the largest increases came in areas of northern Australia and southeastern South America, where the area of land being burnt grew by more than 20% between both models.

However, these increases are currently being offset by human actions. As well as taking steps to reduce the risk of fire, such as controlled burns to remove dry wood, changes in land use are also having an impact.

“The mere presence of humans changes fire behaviour,” Seppe explains. “We are still moving into parts of the world that were previously uninhabited, so areas like savannah that used to burn easily are becoming cropland or pasture which don’t give free reign to fire anymore.”

This means the area available for fires has fallen by around 19% over the past 20 years. While this might mean fewer wildfires, converting natural habitats to farmland is devastating for biodiversity and so this can’t be a solution in its own right.

It’s also not a permanent solution. Human actions are already not enough to prevent wildfires from starting in years with particularly extreme weather, and this will only get worse as temperatures rise further.

Pollution deaths rising with temperatures

As wildfires burn across the planet, they’re releasing increasing amounts of smoke into the atmosphere. Smoke is a complex cocktail of different chemicals which can disrupt weather patterns, break down the ozone layer, and contribute to climate change.

One of the many components of smoke are particulates – microscopic particles of soot and dust that are the last remnants of burnt materials. These are categorised according to their size, with smaller particles able to penetrate deeper into the body.

Smaller than a grain of sand, PM2.5 is one of the most concerning particulates. This means that the particles are small enough to pass into the blood and even the brain, with the resulting health effects estimated to kill between four to nine million people every year.

While wildfires are a significant source of these pollutants, emissions from factories, power stations and cars are currently responsible for the majority of these deaths. However, as the climate warms this picture will change.

Using their own factual and counterfactual models, the researchers behind the second study estimate that 12,566 deaths in each year of the 2010s can be linked to pollution from climate change-driven wildfires. This is up sharply from 50 years before, when just 669 people a year died of the same cause.

This now means that climate change is responsible for around 15% of all deaths from PM2.5 pollution, up from just 2% five decades ago.

While people living near to the fires will be worst affected, co-author Dr Christopher Reyer explains that the effects of pollution extend much further.

“It’s crucial to understand that the impact of smoke from fires extends beyond those living directly in the affected areas – it also significantly affects people living in cities,” Christopher says. “While cities might not face immediate fatalities from wildfires, our study confirms that smoke exposure can lead to serious public health consequences.”

Bringing these deaths down is no easy task. The researchers say that to adapt to wildfires changes will be necessary across all aspects of our society, from building regulations to health policies.

While these will help mitigate the impacts of wildfires, the only way to stop the risk rising even more is to make drastic emissions cuts.