The UK and continental Europe are sweltering in a heatwave due to last until at least the weekend, and the climate crisis is playing a clear role in intensifying extreme temperatures.
Why is it so hot at the moment?
A high pressure system called the Azores High, which usually sits off Spain, has grown larger and pushed farther north, bringing high temperatures to the UK, France and the Iberian peninsula. The UK will cool a little in the middle of the week, says Annie Shuttleworth at the Met Office, as cooler air pushes down from the north, although southern England will still have temperatures in the high 20s.
After this, winds are expected to turn southerly, bringing hot air up from north Africa and the Sahara. “At the end of the week, temperatures will be close to 40C (104F) to 45C across France and Spain and when we get a southerly wind, the UK will then tap into some of that heat,” said Shuttleworth.
Long July days and short nights mean strong sunshine builds up high temperatures, with night-time lows potentially being above 20C in central England and affecting sleep.
Scientists are clear that human-caused global heating is making every heatwave more intense and more likely. “When it comes to summer heat, climate change is a complete gamechanger and has already turned what would once have been called exceptional heat into very frequent summer conditions,” said Dr Friederike Otto, of Imperial College London. “Every heatwave we experience today has been made hotter because of the fossil fuels we have burned over the last decades in particular.”
How hot will it get?
In the UK, there is a strong chance of the hottest day of the year so far occurring this week, surpassing the 32.7C recorded at Heathrow on 17 June. There is also a chance that the all-time UK record could be beaten – that is the 38.7C recorded in Cambridge University Botanic Garden in July 2019. “It’s certainly not out of the question,” said Shuttleworth.
Scorching temperatures above 40C will continue in western continental Europe. The Portuguese government declared an eight-day state of alert on Friday due to a high risk of wildfires. Europe as a whole has just experienced its second warmest June on record, at about 1.6C above average, with extreme temperatures recorded from Spain to France to Italy.
What are the dangers?
Heatstroke and dehydration are the main risks to health and particularly affect young children and elderly people. The UK Health Security Agency issued a level 3 alert on Friday for the south and east of England and a level 2 alert for the south-west, Midlands, north-west and Yorkshire and the Humber regions, which are in place until Friday.
“It is important to keep yourself hydrated and to find shade where possible when UV rays are strongest, between 11am and 3pm,” said Dr Agostinho Sousa, of the UKHSA. “If you have vulnerable family, friends and neighbours, make sure they are aware of how they can keep themselves protected from the warm weather.” Measures include closing curtains to keep rooms cool, avoiding physical exertion in the hottest parts of the day, and carrying water if you are travelling.
“Heatwaves are by far the deadliest extremes in Europe,” said Otto. “In 2020, in the UK alone more than 2,500 people died because of hot days, and those were less hot and less frequent than what we are already seeing this year.”
Dr Michael Byrne, of the University of St Andrews, said: “Extreme heat is a severe threat to public health that – as pointed out by the UK Climate Change Committee only last year – the UK is woefully underprepared to deal with. We urgently need to overhaul UK infrastructure to keep us cool and healthy in a rapidly warming world.”
Prof Hannah Cloke, of the University of Reading, said: “We should remember that heat is most dangerous when it is persistent over several days, especially for those who cannot escape it or gain respite at night-time. That people are dying of heat or cold in Britain in 2022 is frankly a national disgrace.”
Heatwaves can also have a significant impact on mental health, said Dr Laurence Wainwright, of the University of Oxford. “There are significant and positive associations between daily high temperatures and suicide. Roughly speaking, for every 1C increase in monthly average temperature, suicide rates increase by 1-2%.”
Will heatwaves get worse in the future?
Yes, until the climate crisis is ended. “The current heatwave is a dangerous reminder of the accelerating impacts of global warming,” said Byrne. “With London expected to feel like Barcelona by 2050, the UK is braced for more frequent and severe heatwaves over coming years.”
Scientists reported in 2020 that the likelihood of the UK experiencing deadly 40C temperatures for the first time was “rapidly accelerating” due to the climate crisis.
What is the influence of the climate crisis?
The link is now crystal clear. Heatwaves are caused by weather patterns that produce persistent high pressure, cloud-free conditions and dry continental winds during summer.
“Climate change is intensifying these heatwaves as greenhouse gas increases raise temperatures and a warmer, more thirsty atmosphere dries out the soil, so that more of the sun’s energy is available to heat the ground rather than evaporating water,” said Prof Richard Allan, of the University of Reading.
Global heating has been driving up extreme temperatures for some time. In some parts of south-east England, the hottest days of the year have already increased by 1C each decade between 1960 and 2019.
“This shows the UK is already on a warming trend when it comes to heat extremes,” said Dr Mark McCarthy, from the Met Office. Research has shown that some recent events, such as the hot summer across the northern hemisphere in 2018, would have been essentially impossible without global heating.
“Human-caused climate change has set us on a course to see temperature extremes in the UK that would be highly unlikely under a ‘natural’ climate, although urgent action to reduce emissions now can significantly reduce the occurrence of extreme high temperatures in the UK in the future,” McCarthy said.
Human activity is adding more greenhouse gases to the atmosphere every year and the heat-trapping effect of this will only level off when the world reaches net zero emissions.
