A recent heat wave in Western Canada that blew past records and contributed to hundreds of deaths could not have happened without climate change, an international group of scientists has concluded.

And even if the world meets greenhouse gas reduction targets, weather that saw temperatures crest to 45 C in many parts of British Columbia could reoccur every five to 10 years, the World Weather Attribution group said in a paper released Wednesday.

B次元官网网址淎n event of this extremity would have been virtually impossible in the past,B次元官网网址� said co-author Sarah Kew of the Royal Netherlands Meteorological Institute. B次元官网网址淏ut we are going to be seeing more intense and more frequent heat waves in the future.B次元官网网址�

The end of June and early July saw unheard-of temperatures across B.C. and Alberta. The community of Lytton, B.C., reached nearly 50 C and was engulfed days later by a wildfire.

During the heat, sudden and unexpected deaths tripled in B.C. to 719 and weather is believed to have been a significant contributor.

B次元官网网址淲eB次元官网网址檝e never seen a jump in record temperature like the one in this heat wave,B次元官网网址� said Geert Jan van Oldenborgh of Oxford University. B次元官网网址淭hese are incredibly high temperatures for these fairly temperate regions.B次元官网网址�

Faron Anslow of the University of Victoria said several factors contributed to the crushing heat: a dry spring, a lingering ridge of high pressure over the region and a low pressure system off the Pacific coast that pulled heat from east to west.

B次元官网网址淭hat put the icing on the cake,B次元官网网址� he said.

But analysis using 21 different climate models and advanced statistical tools showed those factors wouldnB次元官网网址檛 have been enough on their own to push the mercury so high. Climate change, the paper concludes, made the heat wave 150 times more likely.

In fact, records were broken by such a wide margin that the scientists suggest two possibilities.

The first is that the heat was just bad weather luck, a combination of events that will remain rare B次元官网网址� although less rare than before. The second is that the climate has crossed a new threshold, with an as-yet-unknown feedback loop pushing temperatures past what was previously believed possible.

B次元官网网址淎t the moment, we just donB次元官网网址檛 know whether this is true or not,B次元官网网址� van Oldenborgh said.

B次元官网网址淓verybodyB次元官网网址檚 really worried about the implications of this event. Nobody saw this coming.B次元官网网址�

Co-author Kristi Ebi of the University of Washington said heat waves will be a major public health issue as climate change continues. The toll includes health problems and deaths directly related to heat as well as other conditions such as heart problems or respiratory diseases that are worsened by it.

B次元官网网址淎lmost all of the deaths are preventable,B次元官网网址� she said. B次元官网网址淧eople donB次元官网网址檛 need to die in heat waves.

B次元官网网址淭he possibilities for prevention are critically important to address.B次元官网网址�

The current paper brought together 27 scientists from eight countries. Although it has not yet been published, the authors say it will be submitted for peer review and publication in the near future.

Although scientists used to be reluctant to link climate change with any specific weather event, that has begun to change.

The World Weather Attribution group has done dozens of such studies. The climate news website Carbon Brief has also tracked 350 peer-reviewed studies from around the world that consider human fingerprints in extreme weather.

Climate models are better, statistical methods have improved, computers are more powerful B次元官网网址� and climate change is just that much more unmistakable, said Fredi Otto of Oxford.

B次元官网网址淲eB次元官网网址檝e had 10 years more of increasing rates of greenhouse gas emissions, which means we had 10 years of increasing rates of global warming. Changes in extreme events have emerged beyond the noise of natural variability.

B次元官网网址淎ll this coming together allows us now to link individual weather events to climate change.B次元官网网址�

B次元官网网址� Bob Weber, The Canadian Press