Scorching summer temperatures not necessarily linked to climate change: expert
The heat in BC has led to 11 wildfires throughout the province, but it's not abnormal weather, says an expert.
Twenty high-temperature records were broken across British Columbia during the weekend. Yet there's no direct connection between them and climate change, according to a BC climate expert.
"This increase is not statistically significant," said Faron Anslow, a climatologist with the Pacific Climate Impacts Consortium.
Even though the heat reached 40.7◦C in some parts of the province, like the Kamloops Airport Station, Anslow said there isn't anything out of the ordinary.
“This current hot period qualifies as extreme, but is not particularly rare. 2003 and 2009 were both very warm summers,” he wrote in an email to the Vancouver Observer. The expert said that the current event is caused by strong high pressure systems that prevent cooling winds from the west, off of the Pacific Ocean, from reaching the province. “These conditions, combined with long summer days and lots of sunshine allow for lots of heating and high temperatures.”
That mix results in an increase in wildfires in the province. "At present, I'd be hesitant to link the current bout of fires to climate change until this has been confirmed more rigorously," he said.
"However, heat waves in several locations across the globe in recent years have been linked to human influence, so it's quite possible that in the future, B.C. will see longer and hotter heat waves."
A little hotter every time
The climatologist said that since the year 1900 the province's summer temperatures have been warming by 1.1◦C, with more of that occurring in the northern half of the province.
Yearly temperatures have increased a little more. According to the 2007 Environmental Trends Report from Environmental Reporting BC, throughout the year the total increase is of 1.5◦C in the last half a century. That is “higher than the global average.”
The report says the largest increase in temperature is seen during the winter, not the summer: “By 2050, average winter temperatures are expected to increase by 2-3ºC in the south and by 4-5ºC in the north. Summers throughout the province may warm by 2-3 ºC."
Using Pacific Climate Impacts Consortium projections for the next four decades, Environmental Reporting BC’s paper reasserts that British Columbia can expect more hot days in the future. “There is a 90 per cent chance that heat waves will increase in frequency," it says. "Hot extremes will become more common as the climate warms and cold extremes will become less frequent.”
The file points to greenhouse gas concentrations in the atmosphere as the main cause of the rise in global temperatures.
Temperature Departures from the 1961-1990 average - Annual for 2013. Image from Environment Canada
Wildfires harder to control
During the first 15 days of July, B.C. Wildfire Management Branch registered 11 blazes, nine of which were human-caused.
Regardless of what sparked the flames, firefighters have been struggling to keep them under control. “The warmer it is, the more fires we expect,” said Dr. Mike Flannigan, a professor with the Department of Renewable Resources at the University of Alberta.
Anslow explained that the current upper ridge also leads to very dry conditions which enable forest fires to grow rapidly once they begin. “Add winds to the mix and you have a dangerous combination,” he said.
Like Anslow, Flannigan also said it would be premature to connect the rise of yearly temperatures with the increase in the occurrence of wildfires.
“Fire data is extremely variable year-to-year so for B.C. it is difficult to talk about trends with any certainty," he said, adding: "but there do seem to be more active years recently."
"For Canada, our area burned has doubled since the 1970s, but even at the national scale there is a lot of year-to-year variability,” he said.