Canada's boreal wildfires aren't just bad forest management

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Canada's boreal wildfires aren't just bad forest management<br>Higher fire season temperatures are strongly correlated with increased area burned

Zeke Hausfather<br>Jul 17, 2026

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Over the past week smoke from Canadian wildfires has once again poured into cities across Canada and the northern US. Toronto briefly had the worst air quality of any major city on Earth, Thunder Bay’s readings went off the top of Canada’s air quality health index scale, and unhealthy air alerts stretched from Minneapolis to New York City.

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This smoke-pocalypse has renewed a long-standing debate online that these fires aren’t really about climate change at all, but about forest mismanagement. Decades of aggressive fire suppression, the argument goes, have let fuel pile up. We don’t log enough, thin enough, or do enough prescribed burning The forests are overgrown tinderboxes and we have only ourselves to blame. Climate is a distraction from a problem we created by listening to Smokey Bear’s insidious propaganda.<br>I want to take this argument seriously, because it has a real kernel of truth. The fire-deficit story is a genuine phenomenon in the dry conifer forests of the western United States. But most of what’s burning in Canada is boreal forest, and the boreal is a fundamentally different beast. So in this piece I’ll try to explain why the management argument, largely valid in a California pine stand, mostly falls apart when you move it a couple of thousand kilometers north, and explore what the fire data actually shows.<br>Here’s the short version. Canada’s area burned has surged, and it has surged in step with warming: hot, dry fire seasons burn far more forest, with area burned rises roughly 80% for each 1C increase in fire-season temperature (with a correlation coefficient of 0.61). This relationship is robust to a variety of statistical tests and controlling for confounding variables. The boreal burns in rare, high-intensity crown fires on a natural cycle measured in a century or more, across enormous remote areas that have never been logged, thinned, or effectively suppressed. Only about a fifth of Canada’s burned area over the past four decades was even inside forest regions that have ever been actively managed. You cannot have a fuel-buildup from forest mismanagement in a forest you were never managing.<br>Share<br>Forest mis-management?

The forest-mismanagement argument was, in fairness, based on real evidence from some regions. In the frequent-fire dry forests of the western US that are dominated by ponderosa pine and mixed conifers the natural fire regime is low-to-moderate intensity surface fire returning every 5 to 30 years, historically stoked in part by Indigenous burning. A century of fire exclusion in those forests really did remove that frequent fire, let stands grow denser and more continuous, and build up a “fire deficit” that raises the odds of severe fire (Hagmann et al. 2021). And in that setting, fuel treatments work: Prichard et al. (2021) find wide agreement that mechanical thinning combined with prescribed burning measurably reduces subsequent fire severity. If you’re arguing about the Sierra Nevada, the management story is as important if not more important than the climate one.<br>The problem is that the Canadian boreal is not the Sierra Nevada. It burns in infrequent, high-intensity, stand-replacing crown fires that kill the whole stand on natural fire cycles measured in many decades to centuries (commonly a century or more, and two centuries or longer in the east), not 5 to 30 years. It is, ecologically speaking, supposed to burn this way; black spruce is practically built for it. Fire in this system was never the gentle recurring ground-clearing that suppression interrupted in California. And the burning is astonishingly concentrated: across the boreal, something like 3% of fires account for about 97% of the area burned. This is not a landscape full of many small fires that “used to clean out the fuel.” Rather, its a landscape that waits, and then burns catastrophically under extreme weather.<br>Why do we know that Canadian boreal forest fires are not being driven by mismanagement?<br>First, and most importantly, most of the boreal was never being managed in the first place. As University of Alberta fire scientist Jen Beverly has pointed out, only about one-fifth of Canada’s total burned area from 1986 to 2023 occurred within long-term forest tenure (the land that’s actually logged and managed). The vast majority burns in remote forest with no timber operations. In Canada’s so-called “extensive” fire-management zones there has been no serious suppression efforts historically. Fires there are monitored and largely left to burn unless they threaten people or infrastructure. You can’t blame overgrown, over-suppressed forests for fires in places nobody was suppressing.<br>Second, the fuel-buildup...