Scientists said the research showed global warming was already harming people’s lives and was not only a future threat.
Without rapid cuts to greenhouse gas emissions, such heatwaves would happen every other year by mid-century, the Met Office said. Its analysis showed the average UK temperature during June, July and August was more than 2C above pre-industrial levels.
Hundreds more early deaths than usual occurred at the height of the heatwave, while farmers struggled for water and hay and thousands of houses suffered subsidence.
The research was launched at the UN climate summit in Katowice, Poland, and the Met Office’s Prof Peter Stott, who led the work, said: “World leaders should be listening not just to scientists but also to the people who are being affected by extreme weather events right now. They are seeing it with their own eyes and suffering from it. Humanity just won’t be able to cope with the world we are heading for.”
Stott said scientists were making links across the world between extreme weather events and climate change, from heatwaves in Japan to wildfires in California: “We’re seeing it happen again and again across the world. This whole sequence of events would not have happened without climate change.”
Prof Mark Maslin, at University College London, said: “The analysis clearly shows climate change has already changed our weather patterns and is having adverse effects on people’s lives. It is beholden on all governments to take heed of these warnings and start cutting carbon emissions as quickly as possible.”
John Sauven, an executive director at Greenpeace UK, said: “The link between climate change and extreme weather used to be a fingerprint, it now looks more like a smoking gun. The science is leaving world leaders nowhere to hide. They are the first generation of political leaders with a clear view of the precipice we’re heading towards and may be the last to be able to swerve away from it.”
The heatwave showed the vulnerability of farming and food security to global warming, said Minette Batters, the president of the National Farmers Union. “Our industry is on the forefront of climate change impacts. The summer heatwave was hugely challenging and should be a wake-up call for us all.” She said long-term drought policies were needed, such as making it easier to get planning permission for new reservoirs.
The Met Office analysis used sophisticated computer models to estimate the probability of such a hot summer in the UK in a world with manmade global warming and in a world without it. If humanity’s fossil fuel burning had not more than doubled the CO2 in the atmosphere, there would have been a less than one in 200 chance of the 2018 heat. But in today’s warming world, the probability was one in eight.