Numbers speak louder than words. In the American West and much of the southern United States, the mercury reached 47°C in some cities. An “extremely dangerous” heat wave, according to the National Weather Service (NWS) in a bulletin on Saturday morning.
“Several temperature records are likely and air quality problems will be common in several regions of the United States”, further estimates the NWS. And respite isn’t likely to come anytime soon for the more than 90 million Americans under a high temperature alert, as the heat dome is expected to ‘remain stationed over (these regions) for the next several days. “, predicts the NWS.
16 consecutive days of highs above 43 ° C in Arizona
In Phoenix, a metropolis of Arizona in the south-west of the United States, 47 ° C are expected at the end of the afternoon for what should be the 16th consecutive day of maximum above 43 ° C.
Part of the state is in magenta alert level, a “rare and/or long-lasting extreme heat level” which represents the highest alert level in the NWS. In southern California, firefighters have been fighting several very violent fires since Friday which have ravaged more than 1,214 hectares and led to the evacuation of the population.
For climatologist Daniel Swain of the University of California, Los Angeles, mercury in Death Valley could equal or even exceed the highest air temperature ever reliably measured on Earth, at 54.4°. C registered in the same place in 2020 and 2021, according to several experts.
Other disturbing climatic phenomena
Other regions of the United States are at risk of severe weather. “Strong to violent thunderstorms, heavy rain and flooding are possible in many places, particularly and unfortunately in New England, already saturated” by recent rainfall, according to the NWS.
This region of the northeast of the country, and particularly the state of Vermont, was affected this week by “historic and catastrophic” floods, the result of torrential rains.
In Canada, the number of fires continues to increase, particularly in the west of the country, where in a few days several hundred fire starts have been recorded, mainly triggered by thunderstorms.
And the situation will not improve with “hot and dry weather expected in the coming months”, said Sarah Budd of the BCWS: “We do not expect any respite from the weather”. More than 10 million hectares have already gone up in smoke across the country – 11 times the one-year average of the past decade. The absolute annual record – dating from 1989 – has already been largely exceeded.
Smoke from the fires in Canada once again sent columns of smoke towards the southern neighbour. Several states in the North of America, such as Montana and North Dakota, are thus recording “adverse” levels of air quality. Greenhouse gas emissions are increasing the strength, duration and rate of repetition of heat waves, experts say.
Increase in the rate of heat waves
According to the US Environmental Protection Agency, “heat waves are occurring more frequently than before in major cities across the United States”.
“Their frequency has increased continuously, from an average of two heat waves per year during the 1960s to six per year during the 2010s and 2020s,” she says.