Pre-industrial fires were much worse than today’s, but media ignore them to get scarier headlines
By Tristan Hopper, National Post, July 10, 2023
More of Canada has burned this year than in any other year on record, and it’s not particularly close.
According to the most recent figures from the Canadian Interagency Forest Fire Centre, nine million hectares of forest have already burned. That shatters the previous record of 7.8 million hectares set in 1989, and is more than four times the annual average of Canadian forest burned between 1959 and 2015. These stats are all the more remarkable given that the season is only about half over.
With gargantuan plumes of smoke curling across the continent, New York, Toronto, Ottawa and Montreal all briefly reigned as the most polluted cities on earth. And in late June, NASA observers noticed that the smoke was even starting to reach Europe. As of this writing, the skies above London and Paris are being rendered hazy by fires burning more than 5,000 kilometres away.
As the Washington Post recently declared, “It’s Canada’s worst fire season in modern history.”
Fires in ‘modern history’ a tenth of fires in earlier times
But the key term is “modern history.” Because while the people of 2023 are unaccustomed to seeing summer skies obscured by wildfire smoke for weeks on end, pre-industrial North America actually spent an awful lot of its time on fire.
“The earth has long been a fire environment … we cannot be so bold as to think we can eliminate fire from the landscape,” reads a warning in the introduction to the 1993 text Fire Ecology of Pacific Northwest Forests.
The book was one of the first to detail the emerging science of “fire history.” It’s where researchers look for scorch marks from historical wildfires by taking core samples from trees or digging survey holes in the forest floor.
In virtually every one of these studies, the takeaway is that the wildfires of today are nowhere near as large or as frequent as the fires of 100 or 200 years ago.
In a 2021 paper, UBC researchers examined a stand of old growth forest outside Williams Lake, B.C. For the three centuries before European contact, fires were sweeping through the area roughly once every 30 years. After contact, fires were only striking every 70 years – if they came at all.
That same year, a survey led by the Nature Conservancy determined that the area burned in Pacific Northwest wildfire seasons was only about a tenth of what it used to be in pre-modern times.
“Despite late twentieth-century increases in area burned … Pacific Northwest forests have experienced an order of magnitude less fire over 32 years than expected under historic fire regimes,” they wrote.
Fires before early 1900s worse than today by far
It’s a similar story in the Inland Northwest, the region just to the east. A 1997 study led by the U.S. Department of Agriculture determined that prior to 1900, there wasn’t a single tree around what is now Idaho that couldn’t expect to be hit by a wildfire about every 10 to 20 years.
“Major fire years prior to the early 1900s burned more acreages than any fire years since then,” it read.
A 2007 survey of prehistoric fires in what is now California was particularly blunt in saying that no matter how bad the state’s wildfire seasons got, they weren’t coming close to the way it used to be.
Pre-1800, about 1.8 million hectares of pre-colonization California could be expected to burn ever year. For context, over the last 22 years the median area burned in a California wildfire season is less than one sixth of that (270,000 hectares).
“The idea that U.S. wildfire area of approximately two million (hectares) annually is extreme is certainly a 20th- or 21st-century perspective. Skies were likely smoky much of the summer and fall in California during the prehistoric period,” wrote researchers.
Large fires are ‘normal’
When B.C. and the U.S. Northwest were hit by a particularly active wildfire season in 2020, scientists at the U.S. Department of Agriculture ran the numbers and determined that 2020 was actually the first “normal” fire season the region had seen in more than a century.
“Reports from the early 1900s, along with paleo- and dendro-ecological records, indicate similar and potentially even larger wildfires over the past millennium,” read their analysis. “The 2020 fires were remarkably consistent with historical fires.”
The clouds of smoke now descending on cities in Central Canada and the Eastern United States may seem like a uniquely modern plague, but they were pretty standard for the communities of pre-industrial North America.
The most famous example was the 1780 New England Dark Day, when thick wildfire smoke from Canada plunged large swaths of what is now the U.S. Northeast into total darkness, and caused rivers to be tinged black with soot.
As recently as the 1880s, it wasn’t all that uncommon for summertime train journeys through the Canadian and U.S. West to feature no scenery on account of the smoke.
“Among the valleys, with mountains on every side, during all that trip a mountain was never seen. This was because the fires in the mountains created such a smoke that the whole country was enveloped by it,” reads an 1889 account of a train journey into the U.S. Rocky Mountains.
Indigenous burning shaped landscape
Indigenous societies were used to all this fire, and set many of the blazes themselves, usually to clear land or roust game. Early Canadian explorers often encountered surprisingly pastoral landscapes, not realizing they were seeing lands shaped by centuries of Indigenous burning.
As settlers in colonial Canada threw up fire-vulnerable forts and settlements along their new frontier, often one of the first coercive measures imposed on nearby First Nations were bans on seasonal burning. In B.C., it’s in the 1850s when tree ring data first starts to show a steep dropoff in wildfire frequency.
But it was after the 1950s when fire suppression truly reached its zenith.
After the Second World War, Canada emerged from the conflict with fleets of surplus aircraft and more than a million young men with military training, both of which were employed to maximum effect to stamp out even the most benign and natural of wildfires.
When the Canadians of 2023 compare their wildfire seasons to the past, their only points of reference are from this bizarre postwar era in which technology was able to artificially shrink wildfire season into a shadow of its former power.
This is not to say that warming temperatures aren’t having an effect on wildfire season. By every available metric, Canadian summers are hotter, longer and drier. Even the most vocal critics of Canadian forestry policy acknowledge that climate change is definitely making it easier for trees to burn.
Poor fire management has created ‘tinderboxes’
“B.C.’s history of fire suppression and outdated forest management has turned our forests into a tinderbox that grows more dangerous every year,” wrote the B.C. Wildlife Federation’s Jesse Zeman in a recent critique of Canadian fire policy. But he added the caveat, “warm, dry weather early in the season is part of the problem, to be sure.”
If human-caused rising temperatures are causing more wildfires, however, the primary effect is to undo another human-caused phenomenon of artificially having fewer wildfires.
Ten years ago forestry scientists even began speaking of a “fire deficit.” A 2012 paper in the Procedures of the National Academies of Science determined that even as U.S. wildfire seasons kept breaking records for size and severity, there still weren’t nearly enough fires to purge American forests of accumulated debris.
“Large fires in the late 20th and 21st century fires have begun to address the fire deficit, but it is continuing to grow,” it read.