A man cools off in a fountain in Trafalgar Square in London, England, on Tuesday, July 19. (Neil Hall/EPA-EFE/Shutterstock)
Temperatures in the UK topped 40 degrees Celsius (104 degrees Fahrenheit) for the first time on Tuesday, making it the country’s hottest day.
Prior to 2019, the UK had only seen a city exceed 37.8 degrees Celsius (100 degrees Fahrenheit) once in August 2003.
Since then, it has happened four times in four years. So what was once thought impossible, or perhaps a once in 100 year heat event, now happens almost annually.
UK Met Office Chief Scientist Stephen Belcher and Met Office Chief Meteorologist Professor Paul Davies said there are three things that make these conditions possible.
The first is the so-called “wavenumber 5 pattern”, Belcher, Davies and the Met Office said in a blog post on Tuesday. The wavenumber 5 pattern describes “the difference in surface temperature from its mean values.” It shows that there is a wave-like pattern around the Northern Hemisphere with five high-pressure regions, they explained, adding that these are the places most likely to experience heat waves. The pattern of wave number 5 also explains why it is possible to have concurrent heat waves around the world, Met Office scientists said.
The Met Office says climate change, the second factor, also plays a role. Belcher and Davies wrote in the blog post that the temperatures in the UK are “unprecedented in recorded history”.
“In a climate unaffected by human influence, climate modeling shows that it is virtually impossible for temperatures in the UK to reach 40C,” the Met Office said in the blog.
Belcher and Davies said climate change is primarily due to the build-up of greenhouse gases in the atmosphere. The warmer conditions are the result of these gases combining with atmospheric circulation patterns, such as the wave number 5 pattern, according to the Met Office.
The third factor contributing to extreme heat is environmental and soil conditions, Belcher and Davies said.
“It’s been a dry year in many parts of England. When the sun shines on the ground, dry soils can’t release energy through moisture evaporation, which means more of the sun’s energy goes to warming the air, further amplifying temperatures in England. the UK,” the blog said, adding that climate scientists call this the soil moisture feedback.
“These three elements have come together in the UK: the global pattern of wave number 5 driving high temperatures, in the presence of an already warmed climate due to climate change, further enhanced by soil moisture feedback ” added the Met Office.
The consequences: The UK is woefully unprepared for the impacts of the climate crisis. It has difficulty managing floods when they occur. With the heat, the nation collapses.
On Tuesday, as many fires were lit in London as the city’s firefighters declared a “major incident” and they stretched themselves beyond their capacity. At least four people have drowned as people flocked to beaches, rivers and lakes just to try to cool off. Even an airport runway outside London had to be closed because it was melting in the heat.
CNN’s Brandon Miller contributed reporting to this post.