Professor Emily Shuckburgh, from the University of Cambridge, said: “Extreme heat is a silent killer with more than 2,500 heat-related deaths recorded in England in summer 2020, with the elderly especially vulnerable.
“Climate change is meaning life-threatening heatwaves are becoming more intense and more frequent.”
She said the “descent into a dangerous future” could only be halted by a rapid transition to net zero, and said solutions such as providing more green space in cities could both cut climate emissions and limit the impacts of extreme temperatures.
Some parts of the UK are seeing soaring temperatures after months of below average rainfall.
Farmers who are starting to harvest crops such as barley have raised concerns both about yields and crop and combine harvester fires in the tinder-dry conditions.
Yorkshire farmer Richard Bramley, chairman of the National Farmers’ Union’s environment forum, warned: “We’ve not adapted our water management to the changing climate, we’re way behind.
“We’re lucky we tend to get enough rain as a rule, but we’ve gone from getting it fairly evenly spread to getting it in extremes,” he added.
And he said while water was a concern for farmers, it should be a concern for everyone.