Meteorologists and academics have stated in no uncertain terms that climate change contributed to record-breaking temperatures this week in British Columbia and the U.S. Pacific Northwest.
Those temperatures played a role in a fire that raced up and down a hill in the Fraser Canyon last night, forcing residents of Lytton, B.C., to flee for their lives.
It came after Lytton set Canadian heat records on three consecutive days, peaking at 49.6 C (121.28 F).
A CBS News report described the heat dome that formed over B.C. and the Pacific Northwest as a once-in-a-millennium event.
This heat dome was created when hot air blown in from the sea, encounters hot summer air on land, and is unable to rise because it's trapped by high pressure from the atmosphere.
Michael Mann, an oft-quoted climate expert at Penn State University, has cited the jet stream as one factor contributing to extreme heat waves.
In the current situation in B.C. and the Pacific Northwest, the heat dome diverted the jet stream to the north. That blocked cooler temperatures from flowing south.
Jet streams are currents of fast-flowing air in the troposphere that travel in both hemispheres. The energy for the northern hemisphere's jet stream comes from the difference between cool Arctic air and warmer temperate-zone air.
Because the Arctic air has warmed considerably in the summer, these air currents travel more slowly and loop more broadly—or so goes this theory.
B.C. heat waves are deadly
This week's extended heat wave likely led to hundreds of deaths in B.C.
The province's chief coroner, Lisa Lapointe, stated that there were at least 486 sudden and unexpected deaths in B.C. between June 25 and 1 p.m. on June 30. Normally, there would be 165 of these deaths over that period.
This suggests that more than 300 fatalities could have been linked to the high temperatures.
It's not the first such incident in B.C.
A 2009 heat wave in Metro Vancouver was the subject of a study published in Environmental Perspectives in 2017. In this instance, researchers concluded that in one week that year, 110 people died due to high outside temperatures.
Mann has noted that these types of heat waves are increasing in frequency.
In a paper that Mann coauthored in Science Advances in 2018, he and other researchers highlighted the impact of a "quasi-resonant amplification (QRA)" on extreme summer weather in the Northern Hemisphere.
These QRA events are likely to increase by about 50 percent this century "under business-as-usual carbon emissions", they wrote.
If they're correct and if greenhouse-gas emissions are not slashed, we could see more of these heat waves in the future.
"Some predict a near tripling of QRA events by the end of the century, while others predict a potential decrease."
The paper, which was written two years before the shocking Siberian heat wave of 2020, pointed to numerous other extreme-weather events in the summer in recent years in the northern hemisphere.
"A series of persistent, extreme, and costly summer weather events over the past decade and a half, including the 2003 European heat wave, 2010 Pakistan flood/Russian heat wave, 2011 Texas drought, 2013 European floods, 2015 California wildfires, and 2016 Alberta wildfires have led to ongoing discussion in the scientific literature regarding the relationship between anthropogenic climate change and warm-season weather extremes," the researchers wrote.
They noted that some increases in these extremes of summer weather "can be explained by relatively straightforward thermodynamic processes", such as upward shifts in temperature distribution or the impact of a hotter atmosphere on precipitation.
However, they also maintained that "mechanisms involving atmospheric dynamics are necessary to explain the characteristics—particularly the unusually persistent and amplified disturbances in the jet stream—that are associated with persistent extreme summer weather events".
More recently, Mann wrote How to Win the Climate War and Avoid Disaster. Check out the trailer in the tweet below.
Jet stream linked to Siberian heat wave
The World Weather Attribution website was created several years ago as part of an international effort to communicate the impact of climate change on extreme weather events, including heat waves.
In a WWA analysis last year, scientists from six countries collaborated to examine the links between human-induced climate change and the heat wave in Siberia in the first six months of 2020.
"The results showed with high confidence that the January to June 2020 prolonged heat wave was made at least 600 times more likely as a result of human-induced climate change," they concluded. "We note that even with climate change, the prolonged heat was a very rare event expected to occur less than once every 130 years."
Moreover, they wrote that by 2050, the Siberian region can expect to see temperatures 2.5 C above the average in 1900, but it could rise as high as 7 C above the 1900 level.
The researchers linked very warm conditions in the 2019-20 winter in Siberia to a strong jet stream, which caused more ice and snow to melt. This, in turn, resulted in more darker surfaces that could absorb more heat.
"Overall, the 6 months from January to June 2020 were more than 5 degrees Celsius warmer than average (1981–2010) over the study region," they noted. "This extremely hot period led to local heat records being broken, including at the Verkhoyansk weather station which recorded 38 degrees Celsius on 20 June."