Carney says US and Canada share responsibility for climate change fight

Donald Trump threatened on Friday to impose tariffs on Canada over wildfire smoke drifting into American cities, escalating a climate emergency into a trade threat. He said the United States was being “unnecessarily invaded by filthy, polluted, and unhealthy air” and accused Canada of “willful negligence” in handling the fires.

Mark Carney had already framed the dispute as a shared obligation. On July 16, the Canadian leader said climate change is everybody’s responsibility, including the United States, after U.S. lawmakers pressed Canada over smoke crossing the border and after public anger grew over hazardous air quality.

Carney defended Canada’s environmental record and pointed to clean-energy investments while Washington rolled back its own climate policies. The message put the cross-border smoke crisis into a broader policy fight, with one side treating the fires as a matter for tariffs and the other as proof that climate damage does not stop at the border.

The smoke was hitting major U.S. cities and triggered air-quality alerts across the Midwest and Northeast. More than 800 Canadian wildfires were burning, and Ontario sought federal support for evacuations as the smoke spread. The conditions were severe enough that North American cities were among the places with the worst air quality on Earth.

The episode also fit a pattern that has been building for years. Canadian wildfire smoke has already spread across a third of the United States, and in 2023 Canada was on track for its worst-ever wildfire season. That same year, wildfire emissions reached a record high and smoke made it as far as Europe.

That history makes Trump’s tariff threat harder to separate from the underlying climate crisis. The fires are not contained by national borders, and the smoke now moving through the United States has become part of a larger argument over how much of the burden Canada can carry alone, and how much belongs to a wider North American response.