Heat dome leaves US Southwest facing ‘dangerous’ temperatures
Scientists warn that tens of millions of Americans will be affected by extreme weather caused by climate change
The southern US faces temperatures as high as 46C this week as forecasters warn of “dangerous record-breaking” heat for tens of millions of people.
A high-pressure system known as a heat dome is sitting over the Southwest and south-central parts of the country, acting like a lid that prevents heat from escaping into the atmosphere.
It comes against a backdrop of elevated global temperatures after a summer of exceptional heat in western Europe and a strong wildfire season in Canada.
More than 28mn people live in areas affected by the National Weather Service’s extreme heat warning for the Southwest on Wednesday, and another 32mn are subject to a heat advisory focused on south-central regions.
Scientists have said that recent heatwaves in Europe would have been impossible without climate change and warned that US temperatures were also driven by the man-made phenomenon.
“You don’t need to run an experiment to get an idea these severe heatwaves have a connection to global warming,” said Akshay Deoras, a scientist at the National Centre for Atmospheric Science, which has a global remit but is based in the UK.
Baseline global warming that made last month the second hottest July on record on land and the hottest on record at sea means heatwaves are striking on top of already elevated temperatures.
John Marsham, a professor of atmospheric science at the University of Leeds, said that global climate change had “hugely increased” the chances of a heatwave in the US this summer.
A red-flag warning for imminent critical fire risk has been put in place through to Friday for areas north of Los Angeles due to extreme heat, gusty winds and low humidity.
LA’s emergency management department said that more than 70 public library branches would be available for cooling and shelter, with air-conditioned bus rides to cooler locations on offer, and advised keeping pets indoors.
An “extreme heat” warning was also in place across Death Valley, in California, after a French tourist died last week when his car got stuck in the mud and he tried to walk across scorching salt flats to get help. Authorities warned that the inside of cars could reach “lethal” temperatures within minutes.
The National Weather Service warned of record-breaking heat in the south-central and Southwest, with some isolated areas hitting more than 46C during the day.
Overnight temperatures, which can limit the human body’s ability to recover and trigger health problems, were also expected to break records, the service said.
The NWS warned that the Midwest, south-east and elsewhere could be hit with thunderstorms or flash flooding.
Dallas experienced its record temperatures earlier this week, and forecasts show residents can expect little respite from the searing heat. The NWS’s Texas office said that “meaningful relief” will not come soon, with temperatures predicted to remain high into September.
Forecasters expect this year’s Pacific Ocean warming phenomenon known as El Niño to be the strongest since records began, helping drive global temperatures still higher.
El Niño’s effects vary by region, however, and could bring cooler and wetter conditions to the southern US by the end of this year.