Saturday, July 24

Scientists call for accelerating global preparation for extreme heat

The world must step up preparations for extreme heat, which could come earlier and stronger than predicted, a group of leading scientists has warned after the wave of extraordinarily high temperatures in Canada and the United States.

Canada is a warning: more and more parts of the world will be too hot for humans

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Last week’s “heat dome” over British Columbia, Washington state, and Portland, Oregon, broke temperature records by more than 5 degrees in some places – a peak that would have been deemed impossible a few weeks ago, according to reports. experts, and raising concerns that the climate has crossed a dangerous threshold.

A first analysis of the heat wave, Posted on Wednesday, concludes that human-caused climate change makes extreme weather events at least 150 times more likely.

Temperatures are rising around the world as a result of greenhouse gas emissions, and scientists have long predicted that heat records will be broken with increasing frequency.

“It is the biggest jump I have ever seen”

But the authors of the new study say the latest hikes have exceeded even the worst-case scenarios in climate models. This forces them to review their knowledge of heat waves and to consider the possibility that other parts of the world experience similar temperature surges.

“This is by far the biggest leap I’ve ever seen in the records,” says Friederike Otto, associate director of the Institute for Environmental Change at the University of Oxford, one of the group’s founders. World Weather Attribution who did the last study. “Certainly, we should not expect heat waves to behave as they have in the past … in terms of how to prepare for them.”

A key point is whether the affected areas were simply unlucky or if the climate system has crossed a threshold and entered a new stage where a small part of overall global warming could cause a more rapid rise in extreme temperatures.

There is still no scientific consensus on this, but researchers will now urgently study whether other forms of climate disturbance, such as droughts or a slowdown in the climate jet stream (or jet stream), could be amplifying heat waves.

Another of the authors of the new study, Geert Jan van Oldenborgh of the Royal Netherlands Meteorological Institute, explains that, until last year, standard climate models assumed that there was an upper limit for heat waves that moved approximately twice as fast as general global warming trends.

“We thought we knew what was happening … Then came this heat wave that far exceeded the upper limit. With the knowledge of last year, that was impossible. It was surprising and shocking,” he says. “We have less certainty about heat waves now than we did two weeks ago. We are very concerned that this is going to happen everywhere, but we don’t know yet.”

Similar trends in the world

The headlines have focused on the United States and Canada, which registered marks of 49.6 ° C at latitudes similar to that of the United Kingdom. More than 500 deaths have been attributed to the heat, which has also sparked wildfires, snowmelt flooding, power outages and cracked roads.

Scientists have stressed that similar warming trends can be found in other parts of the world, although they are often underreported, particularly in sub-Saharan Africa, which does not have as many monitoring stations and receives much less media coverage. Parts of Siberia and Pakistan have recently experienced unusually intense heat waves. The hottest days in June were also recorded in Helsinki, Moscow and Estonia.

The World Weather Attribution group had already pointed out the strong links between the climate crisis and other extreme events, such as the 2020 heat wave in Siberia, the wildfires in Australia of 2019-20, the heat waves in Europe during 2018 and 2019 , and Tropical Storm Imelda, which hit Texas in 2019.

More than storms and floods, Otto says human emissions are more clearly and destructively influencing heat waves, which are reaching levels that are not sufficiently represented in current computer models. “What everyone should take away from this study is how the impact of climate change today is largely manifested in the strong intensity and frequency of heat waves.”

The costs – in terms of deaths, illnesses, lost work hours and property damage – are growing rapidly, says Maarten van Aalst of the Red Cross Red Crescent Climate Center and the University of Twente.

“Heat waves top the world’s deadliest disaster charts, both in 2019 and 2020. Here is another dire example, which sadly is no longer a surprise, but part of a very worrying global trend,” he says.

The published figure is probably an understatement, because heat is rarely mentioned on death certificates. Van Aalst urges governments to strengthen early warning systems and measures to counter heat waves. Architects and urban planners should also design buildings and urban centers with more green spaces and cooling zones.

According to scientists, the most urgent thing is to reduce the emissions that cause global warming quickly. With the current level of warming – around 1.2 ° C above pre-industrial levels – the recent deadly heat in the American Northwest is considered extraordinary, but this new study finds that it could happen once every five to 10 years if temperatures global temperatures rise 2 ° C, which could happen as early as 2050.

Translated by Ignacio Rial-Schies.

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