The searing heat that scorched western Canada and therefore the US at the end of June was “virtually impossible” without global climate change , scientists say.
In their study, the team of researchers says that the deadly heat wave was a one-in-a-1,000-year event.
But we will expect extreme events like this to become more common because the world heats up thanks to global climate change .
If humans hadn’t influenced the climate to the extent that they need , the event would be 150 times less likely.
Scientists worry that global heating, largely as a results of burning fossil fuels, is now driving up temperatures faster than models predict.
Canada’s previous national record for top temperature was 45C – but the recent heat within the village of Lytton in British Columbia saw a figure of 49.6C recorded at the peak of the event.
All across the region, within the US states of Oregon and Washington and within the west of Canada, multiple cities hit new records far above 40C.
These temperatures had deadly consequences for many people, with spikes in sudden deaths and large increases in hospital visits for heat-related illness.
Since the beginning of the heatwave, people have linked the weird and extreme nature of the event to global climate change .
Now, researchers say that the probabilities of it occurring without human-induced warming were virtually impossible.
An international team of 27 climate researchers who are a part of the planet Weather Attribution network managed to analyse the info in only eight days.
Unsurprisingly, given the fast turnaround, the research has not yet been peer-reviewed. However, the scientists use well-established methods accepted by top journals.
They used 21 climate models to estimate what proportion of global climate change influenced the warmth experienced within the area around the cities of Seattle, Portland and Vancouver.
They compared the climate because it is today, with the planet because it would be without human-induced warming.
“We conclude that a one-in-1000-year event would be a minimum of 150 times rarer within the past,” said lead author Sjoukje Philip, from the Royal Netherlands Meteorological Institute.
Co-author Dr Friederike Otto, from the University of Oxford, explained what the researchers meant once they said the acute heat was “virtually impossible” without global climate change .
“Without the extra greenhouse gases within the atmosphere, within the statistics that we’ve available with our models, and also the statistical models supporting observations, such an occasion just doesn’t occur,” she explained.
“Or if an occasion like this happens , it occurs once in a million times, which is the statistical equivalent of never,” she told a news briefing.
This type of research, which seeks to work out the contribution of human-induced global climate change to extreme weather events, is understood as an attribution study.
According to the analysis, if the planet warms by 2C, which could happen in about 20 years’ time, then the probabilities of getting a heatwave almost like last week’s drop from around once every 1,000 years to roughly once every 5-10 years.
The authors say that the observed temperatures were so extreme that they lie far outside the range of historical observations. This makes it hard to quantify, confidently , just how rare the warmth dome event really was.
The scientists say there are two possibilities for the acute jump in peak temperatures seen within the region.
The first is that it’s just a particularly rare event, made worse by global climate change , “the statistical equivalent of really bad luck”, consistent with the paper.
