How dangerous are wildfires and how can we stop them from getting worse?

Firefighters use a hose to extinguish flames during a wildfire in Lège-Cap-Ferret in the Gironde, south-west France. Photograph: Stéphane Mahé/Reuters View image in fullscreen Firefighters use a hose to extinguish flames during a wildfire in Lège-Cap-Ferret in the Gironde, south-west France. Photograph: Stéphane Mahé/Reuters Explainer How dangerous are wildfires and how can we stop them from getting worse? The conditions for ferocious fires are expected to worsen as the planet heats up, putting more people at risk Fierce wildfires after back-to-back heatwaves have forced tens of thousands of people across southern Europe to flee their homes , while powerful infernos across Canada and the US choke big cities with thick smoke. How deadly are wildfires? Wildfires directly kill hundreds of people each year. Though they may seem apocalyptic, the death toll is far lower than from floods , which kill thousands, and from heatwaves , which kill hundreds of thousands. But when you factor in smoke, the human cost rises rapidly. The latest study estimates that the air pollution spewed by wildfires kills a staggering 1.5 million people each year. The toxic fumes can reach so far that tendrils of smoke from Australian bushfires have menaced South America, while smoke from Canadian fires – which regularly suffocate cities across the US – have fouled the air in Europe. Last year, a study attributed 22,000 early deaths in Europe to Canadian wildfire smoke in 2023, out of a total of 82,000 deaths. What causes wildfires? Many things can spark a wildfire: natural causes such as lightning, faulty infrastructure such as downed power lines, or people behaving badly. Devastating blazes in recent years have been started by smokers tossing cigarette butts, tourists failing to put out campfires, and even arsonists intentionally setting nature alight. But whether those sparks turn into small fires or raging blazes depends on the weather. Fires need hot, dry fuel to burn, and they spread further with strong winds. How does climate breakdown affect wildfires? Fossil fuel pollution has heated the planet by about 1.3C, raising the risk of prolonged heat that turns forests and grasslands into tinderboxes. In some regions, such as the Mediterranean, global heating is also fuelling droughts that dry out lush greenery. Scientists have found that such shifts have made the wildfires that have happened this year in places including California, South Korea and Australia more likely – in some cases doubling the chance of extreme weather conditions that help fires spread. View image in fullscreen A blaze engulfs trees in Llano, California, on 10 July. Photograph: Ethan Swope/AP Are wildfires getting worse? Even as the planet has heated up, the area torched by fires has fallen. This is because people have taken nature that used to burn freely and turned it into farms or cities – in recent decades mainly in Africa – that stop the spread of flames. The latest models find land use changes an