The likely culprit behind the abnormal weather during B.C. wildfires
New analysis from Climate Central reveals that global warming likely contributed to the hot and dry conditions during and prior to some major B.C. wildfires this summer.
Climate Central used its Climate Shift Index, which is a tool that examines how much more or less human-caused climate change influenced temperatures, to determine how much hotter climate change likely made the weather prior to and during large B.C. wildfires.
“What we do is we use observations and models to create a world that would have happened if we didn’t have all the carbon pollution we’ve emitted since the Industrial Revolution,” said Kaitlyn Trudeau, an applied climate scientist with Climate Central, in an interview with Daily Hive. “And we say, ‘Okay, what would the temperatures be like if we take out all the influence of this carbon pollution?'”
They then compare this with actual temperatures. With this information, they can see what temperature could have been expected without all of the carbon pollution humans have emitted since the Industrial Revolution.
Trudeau looked at where B.C. had some of the major fires this year, including the Bald Range wildfire that threatened Summerland and the Brunswick Creek fire that forced people to evacuate in the Fraser Canyon.
The analysis found that every fire over 200 hectares that burned in B.C. between May and September followed two weeks of climate-driven warming. On average, afternoon temperatures were 2.7°C warmer and overnight temperatures 2.8°C warmer, if climate change didn’t exist.
Trudeau said that this analysis is not attributing the cause of the fire to climate change.
“It’s just looking at how climate change influenced the temperatures around these fires,” she said.
But heat pulls moisture from fuels, and thus can make it easier for burning to happen.
Trudeau said that fine surface-level fuels can dry out in under a day, but the materials on the forest floor can take at least a couple of weeks to dry out from weather, which is why she also looked at temperatures in the two weeks leading up to the forest fires.
She found that in the two weeks before the discovery of the Brunswick Creek fire, it was 4.1°C warmer in the afternoons and 4.8°C warmer overnight, due to climate change.
“A lot of people don’t think about nighttime when it comes to fighting fires, but it’s actually a really important time of day for firefighters to make progress,” said Trudeau.
Nights are typically cooler and more humid, meaning that fire behaviour is calmer, the fuel recovers some moisture, and firefighters get a bit of a break.
“That’s not happening anymore. So the nights are staying warmer. It’s staying drier, and fire activity is really being prolonged almost into like a 24-hour fight.”