A thick, orange haze descends on New York City, turning the sky an apocalyptic shade as millions of Americans are told to stay indoors. The source? Hundreds of wildfires burning thousands of miles away in Canada, sending a plume of “filthy, polluted, and unhealthy air” across the border, as US President Donald Trump put it. This is not just a weather event—it’s a growing political flashpoint, with Trump threatening new tariffs on Canada over the smoke, while scientists point to climate change as the underlying driver.
Wildfire smoke is a complex mixture of gases and fine particles from burning trees, vegetation, and buildings. When wildfires burn large areas—this year nearly 3 million hectares of Canadian land have already been destroyed—the smoke can rise high into the atmosphere and travel for hundreds or even thousands of miles, carried by wind patterns. That’s how soot from Canadian fires can blanket a dozen US states, triggering air quality alerts and forcing people to stay indoors. The phenomenon is not new, but it is becoming more frequent and intense as climate change fuels hotter, drier conditions that make fires burn faster and stronger.
“Explains how wildfire smoke crosses borders, its link to climate change, and why it sparks political tensions.”
Scientists say that burning fossil fuels is driving the kind of climate change that is triggering wildfires sweeping through parts of Europe and North America. Warmer temperatures dry out vegetation, creating more fuel for fires. In Canada, there are currently about 955 active fires, the majority burning out of control. More than 190 of those are in Ontario alone. The fires have forced thousands to flee their homes and have already consumed vast swathes of forest. In response, Canada has invested about C$12bn ($8.5bn; £6.4bn) in forest sustainability and fire prevention, and has a long-standing reciprocal fire-fighting agreement with the US dating back to 1982, as well as a more recent assistance deal from the 2025 G7 summit.
For UK readers, this matters because wildfires are increasingly affecting Europe, too. The same climate conditions that dry out Canadian forests also affect British moorlands: the Cairngorms in Scotland have seen fires burning faster and stronger than before. Wildfire smoke does not respect borders—it can drift across the Atlantic, as seen in 2023 when Canadian smoke reached Europe. While the UK may not face the same immediate smoke blanketing as US cities, the political tensions over who is responsible for fire prevention and climate change are a preview of debates that could intensify in Europe. If the US can threaten tariffs over Canada’s forests, similar cross-border disputes over air quality could emerge elsewhere.
Q: How does climate change make wildfires worse? A: Climate change increases average temperatures and causes more frequent droughts, which dry out vegetation and create more fuel for fires. This makes wildfires burn faster, stronger, and for longer, as scientists have observed in both North America and Europe. The burning of fossil fuels is the main driver of these conditions.
Q: Can countries be held responsible for wildfire smoke that crosses borders? A: International law on transboundary pollution is complex, but countries like Canada and the US have formal agreements to cooperate on firefighting, including a 1982 reciprocal fire-fighting pact. However, when smoke causes health and economic damage, political tensions can rise. President Trump has called Canada’s forest management “willful negligence” and threatened new tariffs, though Canada says both nations share responsibility for tackling climate change.
Q: What should people do to protect themselves from wildfire smoke? A: Health officials advise staying indoors, closing windows and doors, using air purifiers if available, and avoiding strenuous outdoor activity. Wearing N95 or similar masks can help reduce inhalation of fine particles. Check local air quality alerts for updates.
What happens next depends on how the fires evolve and how the diplomatic standoff plays out. Trump has said he will call Canadian Prime Minister Mark Carney to demand an explanation, while Carney’s cabinet has stressed that the two countries remain in constant contact and share a “long history of working together.” Trade negotiations between the US and Canada are already tense, and the wildfire dispute adds a new layer. Whether the tariff threat becomes a reality or is resolved through existing cooperation agreements remains to be seen. Meanwhile, the number of active fires—and the smoke they produce—will depend on weather patterns and firefighting efforts in the coming weeks.
