Opinion: Why Canada’s wildfire smoke is now a fixture for Minnesotans when the weather warms

Vegetation there adapted to a climate that’s now changing. Fires were always part of it but play out differently now.

June 21, 2025 at 1:30PM
A bald eagle flew in front of a sunset in Siskiwit Bay Saturday in Cornucopia, Wis., in 2021 that had been made unusually intense by wildfires. (David Joles/Star Tribune/The Minnesota Star Tribune)

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I have added a new step to my morning routine. After promptly looking up the weather upon waking, I now check the air quality. If it’s bad, how bad is it and how long might I have to try to avoid it? And if it’s good, how long can I hope to enjoy it? It has only been in the past few years that wildfire smoke from Canada has become a persistent risk to the air we all breathe. Why is this?

Scientific advances achieved way back in the 19th century offer insights. In 1884, Wladimir Köppen, a German-Russian botanist and climatologist, first developed a classification system for climate zones throughout the world. How could he accomplish this when vast areas of the globe still lacked any temperature and precipitation records? To create his maps, Köppen built on research conducted by earlier 19th-century scientists who established a strong link between vegetation and climate. Much work had been accomplished on mapping the dominant vegetation types across the world.

Climate is the culmination of the weather conditions prevailing in an area over a long period of time. Weather can and does vary greatly from day to day, but over decades and centuries certain patterns of temperature and precipitation tend to persist, and vegetation responds accordingly.

A vast swath across northern Canada has a subarctic climate, characterized by long, cold winters and short, cool summers. The types of vegetation best adapted to these conditions are conifer forests dominated by black and white spruce with some pine, balsam fir, larch, aspen and birch.

Fire has always been an element of this biome. Historically, about 7.3 million acres have burned annually but in 2023, an astonishing 67 million acres burned. This year’s acreage is on pace to meet or exceed the record-breaking year of 2023. The wildfire season in Canada is starting earlier and extending longer, and some fires even are overwintering — smoldering underground in thick, peaty soils and then flaring up again if dry weather resumes the following spring.

The fire season is changing in Canada because the climate of Canada is changing. Canada’s north is warming at a rate two to three times the global average. The duration of snow cover is decreasing across much of Canada, with a trend toward earlier spring melts. In short, the subarctic climate that for millennia sustained Canada’s vast boreal forest is quickly changing. Climate and vegetation are no longer in sync — a pattern that is being repeated in many parts of the world as global warming intensifies.

What this means is that large, long-duration wildfires in Canada’s boreal forest and the smoke plumes they produce are likely to be a new and persistent phenomenon going forward. According to the U.S. Air Quality Index (AQI), anything above 301 is considered hazardous. On Tuesday, June 3, the air quality index hit an astonishing 800 in Grand Portage at the tip of Minnesota’s Arrowhead region. By comparison, the worst air quality ever recorded globally occurred in New Delhi, India, on Nov. 11, 2022, when the AQI reached 999. We all need to become more alert to air quality warnings and more aware of the potential adverse health effects of wildfire smoke. But we must not acquiesce to these troubling new circumstances.

Every tenth of a degree that the planet warms exacerbates the mismatch between Canada’s boreal forests and the climate, increasing the likelihood of large wildfires. Conversely, everything we do now to stop the rising accumulation of heat-trapping gases in the atmosphere lessens that mismatch. But right now, the Trump administration is charging ahead with policies that will accelerate the buildup of heat-trapping gases.

The next time this summer you find yourself seeking refuge indoors because of hazardous wildfire smoke, take a few minutes to write President Donald Trump (www.whitehouse.gov/contact), USEPA Administrator Lee Zeldin (Zeldin.Lee@epa.gov) and/or Secretary of Energy Chris Wright (the.secretary@hq.doe.gov). Let them know that you understand the link between human-caused climate change and the wildfire smoke that diminishes your quality of life and damages your health, and that you want to know why they are pursuing policies making these problems worse.

Patrick Hamilton is a fellow at the Science Museum of Minnesota.

about the writer

about the writer

Patrick Hamilton