The Met Office has confirmed June was the hottest on record for the UK, eclipsing the last hottest by nearly a full degree.
Across the month, the country recorded an average mean temperature of 15.8C, beating the previous record of 14.9C, recorded in 1940 and 1976 and about 2.5C above the usual June average.
England, Wales, Scotland and Northern Ireland also reported their respective warmest Junes on record.
The Met Office said the record-breaking hot spell bore the “fingerprint of climate change”. Research by its scientists found the likelihood of record-breaking heat had at least doubled since the period around 1940, the forecaster said.
Paul Davies, its chief meteorologist, said: “Alongside natural variability, the background warming of the Earth’s atmosphere due to human-induced climate change has driven up the possibility of reaching record high temperatures.”
The frequency of extreme temperatures depended on the emissions humans continued to produce, Davies said. “By the 2050s the chance of surpassing the previous record of 14.9C could be as high as around 50%, or every other year.
“Beyond the 2050s the likelihood is strongly governed by our emissions of greenhouse gases, with the chance increasing further in a high emissions scenario but levelling off under mitigation.”
The month began with high pressure and temperatures, but after that subsided warm humid air kept the mercury up. “What’s striking is the persistent warmth for much of the month, with temperatures widely into the mid 20s celsius for many and even into the low 30s at times,” said Mark McCarthy, a member of the Met Offices weather and climate records team.
The record comes amid increasing anxiety over the pace and scale of climate change. Surface air temperatures worldwide exceeded the 1.5C Paris agreement threshold in June for the first time, and stayed there for several days, according to the EU’s Copernicus Climate Change.
In the north Atlantic Ocean, sea surface temperatures have been about 0.5C higher than the previous warmest daily surface temperatures recorded in June. Warming water temperatures have led to mass deaths of fish in inland waterways.
Mark Owen, the Angling Trust’s head of fisheries, said the hot weather had already killed thousands of fish across the country.
Owen said: “Where I was this morning on a canal near Birmingham, fish were caught up against a lock and you saw hundreds of seagulls picking up the dead fish. The stench was really quite amazing.
“If July is like June, if August is like June, then we will get far more fish kills than we’ve ever seen. There is a knock-on effect. The fish are the visible bit because that’s what people see floating on the surface but it is also [about] what is happening to the ecosystem.”
In one case in West Yorkshire, people fishing have reported a stream of dead fish moving past.
Dr Andy Bray, the catchment development manager at the Calder Rivers Trust, said: “We’ve got rivers that don’t have any shade, that are straight and that are impounded so there is very little flow. So it’s just kind of a backlog for them to just be heated up in.
“In some places, it’s like a steady stream … of upturned fish floating down the river … there are hundreds in a 30- or 40-minute period. This is a problem that’s going to be happening year on year as we go forward. Maybe not every year, but it’s going to be something that we’ll see again, you might even see again this summer.”
There were an “unprecedented” number of fish deaths in June, according to John Ellis, of the Canal & River Trust. Ellis told BBC Radio 4’s Today programme: “We’ve had more than 60 fish mortality incidents on 21 different canals up and down the UK, and to put that into perspective in a typical year we may see half a dozen incidents.”
Ellis said the increase in deaths was down to a combination of factors including high water temperatures and thunderstorms reducing the amount of oxygen in the water.
The Met Office also said the UK had had 68% of its average rainfall for June, with 52.2mm of rainfall.
Mel Evans, Greenpeace UK’s head of climate, said: “Temperature records are falling like domino tiles as our addiction to fossil fuels keeps cooking the planet. Yet while the dashboard is ablaze with flashing red lights, the prime minister somehow still manages to remain asleep at the wheel. According to his own advisers, Rishi Sunak’s government is failing on climate action right across the board.
“If the heatwaves, droughts and wildfires raging around the world aren’t enough to shake Sunak out of his complacency, people will be wondering what on earth will. We can’t tackle this huge threat without a massive government effort to fix our energy-wasting homes, turbocharge renewables, upgrade our power grid and clean up our transport sector. All of this needs a prime minister leading from the front, but Sunak is skulking somewhere in the rear.”
