Science1 publisherNot yet confirmed elsewhere2 min readPublished
SFU model prices climate-driven Canadian wildfires at $2.1 trillion under 3 to 4 degrees of warming
Simon Fraser University researchers put the climate-driven cost of Canadian wildfires at more than $2.1 trillion this century under 3 to 4 degrees of warming. Holding warming to 2 degrees would keep costs near those of recent decades, lead author Sian Kou-Giesbrecht said.
The Scientist · Science desk
What happened
- The team projected costs under three global warming scenarios: 2 degrees Celsius or less, 3 to 4 degrees, and 4 to 5 degrees.
- Costs counted fire suppression, lost timber yield and lost nature-based recreation in Canada, plus worldwide crop, sea-level and health damage from the fires' carbon emissions.
- In the 3 to 4 degree scenario, the annual cost of climate-driven wildfire impacts reaches $43 billion by the end of the century.
- The model leaves out wildfire health impacts, evacuations, infrastructure loss and economic disruption within Canada.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- constraint Anyone budgeting for Canada would first have to strip out the global share, because the headline total is not a domestic cost estimate.
- exposure Canadian emergency-management and health budgets pay for the categories the model omits, so their exposure in a 3 to 4 degree world is larger than these totals suggest.
- decision Because the cost path follows the global warming level, the lead author argues the size of the late-century bill is being set by emissions decisions made now.
The $2.1 trillion is a price on Canadian fires [11]. Part of it is paid abroad, through the global effects of the carbon those fires release [6]. The paper's title names both parts: Canadian wildfire impacts and global societal costs, attributed to climate change [2].
If the cumulative figure covers all 100 years of the century, it averages about $21 billion a year [16]. The modelled annual cost at the century's end in the same scenario is $43 billion, roughly double that average [10][16]. In this projection, the yearly bill is still climbing as 2100 arrives [16].
Phys.org's account describes the study as among the first to put a price on projected Canadian wildfire activity driven by climate change [17]. Its projection model represents fire weather, vegetation growth, suppression, and ignitions from both lightning and people [7]. Running one model under three warming levels means the gaps between outcomes trace back to the climate scenario [8]. Kou-Giesbrecht said she does not expect the hottest case, "largely because of green energy developments happening primarily outside of Canada" [9]. She called 3 to 4 degrees "a more realistic worst-case scenario" [15].
The comparison with a 2 degree world rests on her description. The published summary gives dollar figures only for the 3 to 4 degree case [4][10][11]. She said that "if we continue to rely on fossil fuels and move farther away from that target, we're going to end up with much, much higher costs" [5].
The exclusions fall unevenly. Health declines abroad from the fires' carbon are in the model [6]; wildfire health impacts at home are not [12]. Nor are one-off extremes such as 2023, when record fires drove evacuations in more than 200 communities and left millions of Canadians breathing hazardous air pollutants [13]. Kou-Giesbrecht said the numbers are likely conservative for these reasons [12][13].
I'd treat the $2.1 trillion as a floor for a 3 to 4 degree world, with one condition. It is a floor on the worldwide cost of Canadian fires, and the domestic share would have to be separated out before a Canadian budget could use it [11][6].
"Societal and economic costs of wildfire are highly dependent on the actions that we take to mitigate climate change right now," Kou-Giesbrecht said [3]. She said immediate, drastic cuts in greenhouse gas emissions that hold warming to 2 degrees are the only available path to limit the economic and environmental consequences of wildfires in Canada [14].
What to watch
- Whether the full paper reports dollar figures for the 2 degree and 4 to 5 degree scenarios, and how much of the $2.1 trillion falls inside Canada.
- Follow-up projections that add evacuation, infrastructure and smoke-health costs, or extreme seasons like 2023, to the same model.