That temperature beat the all-time high record of 38.7C in July 2019 at Cambridge Botanic Garden and came after the first ever red extreme heat weather warning was issued for large parts of England.
NationalWorld has spoken to experts to understand whether extreme heat will become more frequent in the UK, and which areas will be most affected by the change in the climate in the future.
Will 40C temperatures in the UK become normal?
Dr Nikos Christidis told NationalWorld that extreme temperatures are expected to become common in the UK in the future.
He said: “The chances of seeing 40C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence.
“The likelihood of exceeding 40C anywhere in the UK in a given year has also been rapidly increasing, and, even with current pledges on emissions reductions, such extremes could be taking place every 15 years in the climate of 2100.”
Dr Mariam Zachariah, Faculty of Natural Sciences, The Grantham Institute for Climate Change Research Associate at Imperial College London, agreed that more extreme weather is likely in the UK in the future, as climate change is continually warming temperatures in all parts of the world.
She said: “Seeing that we are continuing to put greenhouse gases into the atmosphere we can expect such temperatures to become more common in the future.”
Asked whether the 40C highs in the UK this week were a “one off”, Professor Roland Gehrels, Head of Department of Environment and Geography at University of York, said that is not the case and such extreme temperature “will be the new norm”.
Prof Green added that hotter weather will “come faster than predicted” pointing to the Met Office’s recent simulated weather forecast for 2050 which shows weather maps remarkably similar to the one that was shown for Tuesday (19 July).
Data from the Met Office which calculated the mean daily maximum temperature every month in the UK shows how mercury levels are continuing to climb.
In July 2011, the maximum air temperature recorded was 18.7C. Ten years later in July 2021, the maximum air temperature recorded was 21.1C.
From the chart we can see temperatures spiking and dropping in July throughout the years which indicates the extremity of the weather.
Is it likely we will get more extreme heatwaves in the future?
Heatwaves are becoming more likely and more extreme as the planet continues to warm.
Since the industrial era began around the nineteenth century, the world has already warmed by about 1.1C and is expected to continue rising unless governments around the world make steep cuts to emissions.
Dr Christidis said that “while a 1C background temperature increase may not seem significant, the resulting increase in the severity of extreme heat events is already evident in the observed record”, and this has “widespread and significant impacts.”
The Met Office has recorded the monthly mean daily maximum air temperature in the UK since 1884.
The darker colours congregating towards the right hand side of the chart indicate how we are experiencing more high temperatures in July in the 21st century compared to the 20th century.
According to the UN’s climate science body, the Intergovernmental Panel on Climate Change, we are living in the hottest period for 125,000 years.
Dr Zachariah said: “When we look at the global warming trends we see that the different global regions are also warming and as a result we see that the hot extremes are expected to become more common.”
Which UK areas are likely to be impacted the most by extreme temperatures?
Dr Christidis said: “In a recent study we found that the likelihood of extremely hot days in the UK has been increasing and will continue to do so during the course of the century, with the most extreme temperatures expected to be observed in the southeast of England.”
Dr Mariam also agreed that despite everywhere in the UK expecting to slightly shift to warmer regimes, it will mostly be the southern parts of the UK that will be “more prone to heatwaves.”
She said: “This is because it is this part of the country that is influenced by the maritime winds that come in from the Sahara and the high pressure systems that come off the coast.”
Is the extreme heat due to climate change?
Dr Roland Gehrels said “it is clear that climate change makes these types of events much worse” despite it always being “difficult to prove” that it causes a single event.
He added: “If it hadn’t been for climate change, the current heatwave wouldn’t be so bad.”
Richard Allan, professor of Climate Science at the University of Reading, also agreed on the impacts of climate change on extreme weather.
He explained: “Heating from greenhouse gas emissions due to human activity has made the atmosphere warmer and more thirsty for water which can parch and scorch one region and deluge the larger amounts of moisture in storms elsewhere.
“This is intensifying heatwaves and making them more likely because moderate hot spells are tipping over the threshold into heatwave conditions.
“Without rapid, sustained and strong cuts in greenhouse gas emissions, 40C heatwaves will become the norm in the UK.”
Meanwhile, Dr Zachariah added: “Climate change is definitely the cause for the temperatures and the magnitudes that we are seeing now. However there are also other factors that are driving heatwaves.
“It could either be the dry winds that are coming in from the Sahara region in Africa and the other reason is the high pressure systems which causes windless atmosphere, cloudless skies and high temperatures that causes the weather we are experiencing right now.
“However climate change is making it worse and it will continue to make such events worse as we continue into the future if we do not stop anthropogenic emissions.
“Until we reach the target we should all be braced for such temperatures in the future.”
Why does the hot weather indicate the importance of reducing emissions?
During the spell of extreme heat the UK is currently experiencing travel and healthcare have been disrupted, and schools have been closed.
At least five people have died in and around water over the past two days amid warnings about the dangers.
The extreme heat causes a danger to life and Dr Zachariah told NationalWorld that “as a country we are not prepared to deal with temperatures as high as what we are seeing now.”
She said: “We would require immediate adaptation as well as long term mitigation strategies to help cope with such temperatures going forward.”
Dr Zachariah said as a community it would require “a lot of effort to withstand these temperatures.”
She added: “We should take this as an indication to start working towards adapting ourselves to higher temperatures in the future.
“We should definitely be worried if we do not take action.
“For a part of the world that is not used to such temperatures it will have long standing impacts, be it health, agricultural practices, or infrastructure.”