Focus: Global Warming and Climate Change causes and effects. Video / AP / NASA
Temperatures in California's Death Valley reached 54.4C (130F) on Sunday, possibly the highest ever reliably recorded on the planet.
The extreme temperature was noted by the United States National Weather Service's automated weather station at Furnace Creek, near the border with Nevada, at 3.41pm.
"If verified, this will be the hottest temperature officially verified since July of 1913," said NWS Las Vegas, emphasising the reading was preliminary.
Death Valley - a strip of land between two mountain ranges - is the lowest, driest and hottest location in the US and one of the hottest places on earth.
The Valley's Greenland Ranch hit 56.7C (134F) on 10 July 1913, but some experts question the accuracy of old temperature reports.
The 1913 reading became the planet's hottest in 2013 after a World Meteorological Organisation (WMO) investigation dismissed a 58C (136.4F) temperature thought to have been recorded in Libya in September 1922.
A committee reported the Libya reading was likely incorrect due to human error, as well as the type of thermometer used. This, along with inconsistencies with other temperatures in the region, meant the temperature was removed.
The only other WMO-verified temperature higher than those taken at Death Valley are from July 1931 in Tunisia, where a reading of 55C (131F) was recorded. This too has been challenged over its accuracy.
Some climatologists consider 53.8C (129F) readings recorded in Death Valley on June 30, 2013, and in Kuwait and Pakistan in 2016 and 2017, respectively, as the highest ever reliably measured on the planet.
Death Valley National Park is one of the hottest places on earth. Photo / Getty
Sunday's reading will now be investigated by the National Center for Environmental Information and the WMO.
If verified, it would be the hottest August day ever recorded in the US, and the third highest temperature ever recorded, after the 1913 and 1931 readings.
But some extreme weather watchers believe it could end up being verified as the hottest ever reliably recorded on the planet if the historical figures are questioned.
Bob Henson, a meteorologist, said: "It's quite possible the Death Valley high set a new global heat record.
"The extreme nature of the surrounding weather pattern makes such a reading plausible, so the case deserves a solid review."
Death Valley National Park. Photo / Getty
"There are nagging questions about the validity of even hotter reports from Death Valley in 1913 and Tunisia in 1931.
"What we can say with high confidence is that, if confirmed, this is the highest temperature observed on Earth in almost a century."
A 2019 study found the planet has entered a "new climate regime" with "extraordinary" heat waves that global warming is worsening.
Much of the Western US has been gripped by suffocating heat since late last week.
On Friday, Oakland, California, hit 37.7C for the first time on record in August, while Phoenix tied its highest temperature for the month: 47.2C.
The record temperatures have caused a number of fires across California.
A blaze in northeastern parts of the state spawned a swarm of fire tornadoes prompting what is believed to be the first-ever issued fire tornado warning by the National Weather Service.
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