Scientists sifting through data to find links to extreme weather
This article was written by Kate Allen and was published in the Toronto Star on June 20, 2024.
As the GTA and much of Eastern Canada swelters through a third straight day of extreme heat, a few questions reliably pop up: Is the splashpad open? What’s the least sweaty way to get to work? How much ice cream is reasonable for a single adult to consume over a 24hour period?
And then the big one, the one that rattles around so often these days: is this climate change?
A new, prototype rapid extreme weather attribution system piloted by Environment and Climate Change Canada will be getting a workout in the coming days as it processes reams of data to identify the fingerprint of human-induced warming in the heat wave. The team joins a growing group racing to identify the involvement of climate change in the immediate aftermath of extreme weather, from floods to wildfires to droughts.
While these programs are run by research scientists, their primary audience is not academics: it’s you, the public.
“Attribution science” is intended to break through the disconnect between the global, gradual shifts of climate change and our lived reality on the ground.
Event attribution “can help people understand how climate change is impacting us here in Canada,” said Megan Kirchmeier-Young, a Toronto-based research scientist at Environment and Climate Change Canada’s climate research division.
“If we talk about global temperature increases, it can seem a bit disconnected from our everyday lives. But it’s definitely not — we are feeling the effects of climate change, and through extreme events like this, this is a way to understand that.”
Meteorologists on Wednesday warned that this week’s heat wave is very rare for so early in the summer, and risks breaking multiple records. It’s also very dangerous. Heat is often called the “silent killer,” because it affects so many vulnerable groups — children, the elderly, people with chronic illnesses — but often leaves its mark by exacerbating underlying conditions.
Normally, determining the role of climate change in a heat event would take months or even years. All the research groups rely on the same basic methodology: they use computer models and statistical methods to analyze how likely a given weather event is in today’s climate, compared to the likelihood of the same event in a climate unpolluted by the burning of fossil fuels. And they hustle to release their findings in the immediate aftermath of an event, before the public’s attention moves on.
Some aim even earlier. On Monday morning, as the mercury was just beginning to rise, a U.S. nonprofit called Climate Central sent out an alert: According to their rapid forecast analysis, the high temperatures predicted for Toronto this week were made twice as likely due to climate change.
Unlike Environment Canada’s program and many others, which rely on observed conditions in the recent past, Climate Central’s “Climate Shift Index” uses forecasts to estimate how human-caused climate change has influenced the chances of a particular daily temperature. The group spent more than a year and a half building and testing the system, which covers the entire globe and sends out realtime alerts when a region is experiencing heat significantly influenced by the effects of burning fossil fuels.
(The system, which uses a peerreviewed methodology, is also used for retroactive studies.)
“Ultimately, this is a communications tool. We really developed this tool because we want people to see, feel, touch and taste climate change as it’s happening, not, you know, not days or weeks after,” says Andrew Pershing, vice-president of science at Climate Central.
Think of it like a rapid test for COVID-19, says Pershing: a helpful screening tool that can be confirmed with a more comprehensive, detailed test analysis on, like Environment Canada’s new system, which Pershing calls “really exciting.”
One of the reasons Canada wanted an in-house system, says Kirchmeier-Young, is to ensure every significant heat event in the country gets attention — not just the highest-profile ones, like the 2021 heat dome in British Columbia that killed 619 people.
She says Environment Canada’s prototype won’t be used for forecasts for a few reasons, including that leading up to and during an event, the department’s priority is preparedness: public safety is the most important message.
“Any sort of climate change attribution information needs to come after that,” she adds.
The research team hopes to have the results of its analysis of this heat wave available by the end of next week, if there are indeed results to share, and to keep refining the prototype system throughout the summer — one that will likely provide lots of opportunities, since the department has also forecast extremely high chances of warmerthan-average temperatures across most of the country.
On Thursday, World Weather Attribution, perhaps the best-known group in the field of attribution science, released a study of the extreme heat that afflicted the southwestern U.S. and Mexico earlier this season — temperatures caused by the same heat dome that is punishing Eastern Canada now, before the pronounced, slow-moving ridge of high pressure air that caused it to shift northeast over the continent.
The peak of the heat wave, which killed more than 125 people in Mexico, was made 35 times more likely because of human-induced climate change, the study found. The superwarm nighttime temperatures experienced in the region — one of the most dangerous parts of a heat wave, because it robs our bodies of a chance to cool off — were made 1.6 degrees hotter and 200 times more likely.
The studies don’t always conclude climate change played a role. A World Weather Attribution analysis released in April found that severe drought in southern Africa this year, which has caused massive crop failures and food shortages for millions of people, was primarily driven by El Niño, a naturally occurring climate cycle.
Pershing says that events with outsized climate influence tend to get a lot of attention, but even one that is only two or three times more likely is still a big deal.
“They’re telling you that the world is changing, that these things are going to keep hitting us over the head.”
‘‘We really developed this tool because we want people to see, feel, touch and taste climate change as it’s happening, not, you know, not days or weeks after.”
ANDREW PERSHING, VICE-PRESIDENT OF SCIENCE AT CLIMATE CENTRAL
My Climate Change Website 