A report saying climate change has made the UK warmer and wetter comes after flash flooding and a mini-heatwave in England last week.

Britain has become warmer, wetter and sunnier this century due to climate change, an annual report by leading meteorologists said Thursday, prompting warnings of record summer temperatures in future decades.

The study—the State of the UK Climate 2020—found that last year was the third warmest, fifth wettest and eighth sunniest on record in the UK.

It was the first time that a single 12-month period has registered in the top 10 for all three variables.

The trend has already led to increasingly extreme weather, as Britain's temperatures rise "slightly above" the global mean, the report said.

Lead author Mike Kendon, of the National Climate Information Centre (NCIC), said it was "plausible" the country could regularly hit summer temperatures above 40 degrees Celsius (104 degrees Fahrenheit) by 2040, even with climate change mitigation policies.

The UK's highest temperature ever recorded is 38.7 degrees Celsius (101.7 degrees Fahrenheit), set in July 2019.

"We're already seeing climate impacts globally and in the UK from our changing climate and, clearly, those are set to continue," Kendon told BBC radio.

The report revealed that 2020 was the UK's third warmest year since records dating back to 1884, with all the top 10 hottest having occurred over the last 20 years.

The decade since 2011 has been on average 0.5 degrees Celsius warmer than the 1981–2010 average and 1.1 degrees Celsius hotter than 1961–1990.

Britain has also been on average six percent wetter over the last three decades than the preceding 30 years.

Six of the 10 wettest years since 1862 have occurred in the last 22 years.

Professor Liz Bentley, chief executive of the Royal Meteorological Society—which publishes the annual report in its International Journal of Climatology—said UK heatwaves would become "much more intense" and likely top 40 degrees Celsius.

"It'll start to become something that we see on a much more regular basis," she added.

'Front and centre issue'

Last week, flash flooding in London followed a scorching mini-heatwave, while the Met Office this month issued its first ever "extreme heat" warning.

Similar extreme weather events have occurred around the world in recent years, including flooding in South America and Southeast Asia, record-shattering heatwaves and wildfires in Australia and the US, and devastating cyclones in Africa and South Asia.

Just this month, historic floods killed at least 180 people in Germany and at least 99 in China, while monsoon landslides and flash flooding in Bangladesh left at least 14 people dead.

John Kerry, the former US secretary of state turned climate envoy, called Thursday for more adaptation funding to make countries "more resilient".

"Adaptation has not received the level of input and funding that it needs," he said at a London Science Museum discussion alongside former UK leader Tony Blair.

"It's got to become a front and centre issue for governors, mayors, prime ministers, finance ministers."

Britain will host the crucial COP26 summit in November, when scores of countries will try to agree collective measures to prevent catastrophic climate change.

Tom Burke, chairman of environmental think-tank E3G, said the gathering would be the first of its kind where "the science of climate change has been validated by events".

"It's no longer what scientists say, it's what people are experiencing... in their own lives," he told reporters, noting Prime Minister Boris Johnson needed to be "much more visible" diplomatically ahead of COP26.

Johnson's spokesman said the issue was "a priority" for the British leader and that he was "proud of what this government's doing to tackle climate change".