Wildfire expert Bob Gray has dismissed US claims that Canada’s forest management is to blame for cross-border smoke, calling the accusations scientifically unfounded. The criticism follows former US President Donald Trump’s threat to impose tariffs on Canada over wildfire smoke affecting American air quality.

Trump’s tariff threat and Republican pressure

In a Truth Social post, Trump stated he would “hold Canada responsible” for not “properly managing their Forests,” alleging the smoke cost the US “Billions of Dollars.” He claimed he would discuss the issue with Prime Minister Mark Carney, though no concrete tariff proposal was outlined. The US Supreme Court has previously limited Trump’s ability to impose emergency tariffs.

Earlier, four Republican congressmen from Michigan wrote to Carney, stating, “American lungs are paying the price for Canadian inaction on wildfires, year after year.” Neither the congressmen nor Carney’s office responded to requests for comment.

Canada’s response and cross-border cooperation

Eleanor Olszewski, Canada’s federal minister of emergency management, confirmed ongoing collaboration with the US under agreements signed in 1982 and at the 2025 G7 meeting in Alberta. She noted constant communication between the two nations but did not address criticism of Canada’s forest policies.

Wildfire realities: Science over politics

Gray, a certified wildfire ecologist, highlighted that wildfire smoke routinely crosses the US-Canada border in both directions. He cited examples, including 2020 US fires choking Vancouver and a 2023 Washington state wildfire nearly destroying Osoyoos, BC subdivisions.

The Ontario fires, ignited by a July 12 lightning storm, burned under extreme conditions. Gray explained that the Fire Weather Index was off the charts, with dry fuels and high winds making suppression nearly impossible. He noted that Canada’s wildfire tactics mirror those of the US, including “modified response” strategies for low-risk fires.

While acknowledging Canada could increase prescribed burning, Gray stressed that fuel thinning would not have stopped the current Ontario fires due to their remote locations. He also pointed to economic barriers, with fuel treatments costing $1,500–$10,000 per hectare, and noted that US tariff policies hinder viable markets for removed wood fibre.

“We don’t have a Canadian fire problem or an American fire problem, but we have a North America fire problem,” Gray said.