You don’t have to look far to explain the heatwave – it’s climate change

Exceptionally high temperatures so far north ‘impossible without human influence’

Warnings of 45 degree temperatures in northwestern USA and western Canada, the World Meteorological Organisation report for June reads as if the Earth has taken another step towards Climate Armageddon. An "exceptional and dangerous heatwave is baking" places that are "usually more synonymous with the cold", said the WMO, cautioning of dire consequences.

It is a one-in-10,000 years event that has led scientists to conclude human-induced climate change – not just weather variability – is fuelling temperatures. Across the Northern Hemisphere records have tumbled.

"It's warmer in parts of western Canada than in Dubai. I mean, it's just not something that seems Canadian," said Environment Canada's senior climatologist David Phillips.

Nearly 500 deaths are blamed on the heatwave in British Columbia alone, while extra demand for air-conditioning sparked electricity blackouts and roads buckled in the heat.


The so-called “heat dome” over the region has caused difficulties for people, animals and vegetation; air pollution has risen because of hot stable air, while the risks of forest fires has jumped massively.

Meanwhile, landslides are now threatened by melting glaciers. Transport systems not built for such high temperatures are struggling to cope, while energy companies plead with people not to use air-conditioning in places.

So many temperature records have been broken it is difficult to keep track. This happened repeatedly across the Pacific Northwest in cities such as Portland, Oregon and Seattle.

Canada’s record occurred on Sunday in Lytton, British Columbia (at the same latitude as London), recording 46.8 degrees. By Tuesday, that was 49.6C, higher than Las Vegas’s hottest-ever day, 1,000 miles south in the Mojave desert.

"The heat is more typical of summer temperatures in the Middle East than a province which is home to the Rocky Mountains and Glacier National Park. There is a consequent risk of high glacier melt," said the WMO.

The "heat dome", a zone of high pressure air, is stalled from the Arctic to California, which has trapped heat and allowed it to accumulate. It is like trying a difficult to shift sumo wrestler, says Phillips.

‘Human influence’

Climatologist Prof Peter Thorne of Maynooth University, Ireland's most senior scientist with the Intergovernmental Panel on Climate Change (IPCC), says sharply hot days have always happened. However, and it is a big however, scientists today use so-called "attributional analysis" to determine whether the temperatures have been caused, or influenced, by climate change.

He has no doubt this will be evident in British Columbia’s blistering heatwave, as it was with Australia’s devastating 2020 experience. Temperature of 49.6C so far north are “ impossible without human influence” he adds.

"Climate change is loading the weather dice against us," Prof Katharine Hayhoe of Nature Conservancy told the Guardian. "We always have a chance of rolling a double six naturally, and getting an intense record-breaking summer."

“But decade by decade as the world warms, it’s as if climate change is sneaking in and taking one of those numbers on the dice and turning it into another six, and then another six. And maybe even a seven,” she went on.

The climate threat has been clear for decades from melting ice sheets in polar regions, or more ferocious hurricanes etc, but research shows that record temperatures are making many people wake up to the threat.

In Ireland, it may be different, since flooding and more damaging storms caused by climate change will most likely be the way in which the island will suffer in coming years. But they are not a remote possibility, either.

Tipping points

The North American heatwave occurred just as draft findings emerged from a major IPCC report due to be published next year. It warns life on Earth will be “fundamentally” reshaped in coming decades even if humans cut greenhouse gas emissions.

The finding is not surprising for anyone familiar with climate science, Thorne agrees, though the report “will change beyond recognition” once thousands of review comments from experts and governments are included.

That may be so, but the direction of travel is clear. Tipping points are increasingly close, that once crossed could trigger and amplify cascading crises across the planet, with one ecosystem collapsing after another.

“Life on Earth can recover from a drastic climate shift by evolving into new species and creating new ecosystems. Humans cannot,” the draft report adds darkly.

The exact timing of tipping points and the links between them is not well understood, so they have been under-reported before, explains Simon Lewis, professor of global change science at University College London (UCL).

“The blunter language from the IPCC this time is welcome, as people need to know what is at stake if society does not take action to immediately slash carbon emissions,” he underlines.

The North American heatwave is "unusual, extremely dangerous", but not surprising, says UCL professor of disasters and health Ilan Kelman. And such heatwaves are coming to many other places across the planet soon.

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times