"I told them it was a disgrace that they still give climate deniers airtime at a time like this. I won't be part of such charades any longer." But as the tones of the Drifters' Save the Last Dance for Me faded, BBC Radio Cambridgeshire's presenter pondered, "The summer has [been] one of the hottest and driest on record … does this mean climate change is real?" And among his interviewees was Phillip Foster, who declared the rise in temperatures was a temporary trend due to the sun, not man-made carbon dioxide – an easily-debunked furphy. A child cycles on parched grass from the lack of rain in Greenwich Park in Britain. Credit:AP The next day, 11 weather stations in Germany broke or tied all-time highs. Finnmark, inside the Arctic Circle, recorded an unthinkable 31.2 degrees. In Norway they were warning drivers to watch out for reindeer sheltering in tunnels from the heat. The mercury threatened to set records in Spain and Portugal. In July, Montreal recorded its highest temperature in 147 years of record-keeping, German farmers abandoned ruined grain crops, and the Ouargla weather station in the Algerian Sahara hit an African record: 51.3 degrees.

Read says the debate really needs to move on. "It just doesn't make sense any more in 2018 and, in the middle of this summer, it just isn't good enough any more to just frame the debate 'is climate change real?' " he said. "There are other debates we need to be having, like what are we going to do about it. Not this one any more. And there are many, many people out there who feel the same way." The heatwave grips the UK - will it budge the thinking of climate change deniers?

Dwelling on the old debate causes great damage, Read says. "It gives people the impression that the scientific debate is still alive. It's like the 'merchants of doubt' idea." A tobacco executive said "doubt is our product" on the link between cigarettes and cancer. "As long as the BBC and other media give the impression that there is any significant doubt about this … then people won't take action." Read worries it's part of a bigger trend: extremists have weaponised free speech, insisting on platforms to publicly debate the absurd, to spread conspiracy theories and clog up sane debate. Any move to ignore them is branded censorship. More extreme fires, more often. The Carr Fire burns near Redding, California. Credit:AP

"The free speech argument is completely bogus. We're not stopping anyone's free speech from going on Twitter. Plenty of fools have gone on Twitter to attack what I'm saying. But what does the BBC do, what do responsible media organisations do? That's a separate question." Anyway, no one needs to listen to the radio to find out whether it's hot outside. Author Michael McCarthy, one of Britain's leading writers on the environment, wrote in The Guardian last week that we are witnessing "a historic shift in the way that the threat of climate change is perceived by the world, from prediction to observation". The science so far has been prophecy, hedged by uncertainty and variability, enough for deniers to sow doubt. The heat takes its toll on sunflowers in Wehrheim near Frankfurt, Germany. Credit:AP

"Observation is different," wrote McCarthy. "Seeing things happening around you cannot be gainsaid." And there's plenty to observe. Nine of Britain's 10 warmest years on record have been since 2002 – and the other was 1990. Seven of its 10 wettest years have come since 1998. Britain has always been a place of crazy weather, perched between ocean and continent, but the climate change signal can now be seen and felt, not just calculated. Science is also getting better at separating the climate change signal from the weather noise. A massive bushfire burns near Redding, California. Credit:AP

A new area known as "detection and attribution" is able to – almost in real time – analyse an extreme weather-related event and – sometimes – tell you whether and by how much climate change is to blame. It is cutting-edge science that requires a heap of computer power, but it's starting to show results. For example, climate change made the heatwave in northern Europe in June and July more than twice as likely to happen, according to preliminary calculations by the World Weather Attribution Project, led by Oxford University's Dr Friederike Otto. A heatwave and lack of rainfall is pummeling crops across Europe as far as the Black Sea. Credit:Bloomberg "In Ireland, the Netherlands and Denmark there are clear trends towards more heat waves," the study, which was non-peer reviewed, found. The close to record-high temperatures in these areas were likely to recur within four to seven years.

"They have simply become more likely due to anthropogenic [man-made] climate change." The same group looked at Cape Town in South Africa, and found climate change had made this year's drought three times more likely – and there would be more like it, more often. Loading Replay Replay video Play video Play video They also had a look at extreme rainfall and flash floods in south-western Japan in early July, but found they were compatible with natural variability, without a clear signal of climate change influence. A view from Primrose Hill shows burnt grass from the lack of rain during what has been the driest summer for many years in London. Credit:AP

The technique allows scientists to home in regionally and assess the effects of climate change in a very particular landscape, says Professor Corrinne Le Quere, director of the centre of climate change research at the University of East Anglia. For example, floods can be caused by the heavier rain predicted by climate change, but also by land management. "If you are able to say the climate change contribution is so much, land management is so much and natural variability is so much, then you can really put your efforts in the right place and plan for the long term," she says. Rupert Read, tired of debating climate change,. Le Quere says techniques such as these can help move the conversation on. She is constantly asked about the link between weather and climate change, and now she has the tools and the research to answer.

"It makes what I say about climate change much more powerful. I'm able to say, 'Look, in the very same summer, we have a heatwave here, in Japan and in America and it's indicative of a very strong signal in the background of climate change.' "We can talk about it with more confidence. Attribution is so obvious in the heat-related events." But what is even more helpful than that is people can tell for themselves now, she says. "If you ask an adult of 30 years or older how was it like when you were young, they can tell the difference themselves. It's the same story all around the world." Of course, climate change deniers are not surrendering; they are changing tactics.

The Global Warming Policy Forum in Britain has striven greatly to sow doubt on climate science and counted high-profile politicians in its ranks. It has hosted former prime ministers Tony Abbott and John Howard. The former said climate change, if it existed, was "probably doing good" and the latter dismissed global warming as a "religion" and the "latest progressive cause". But the forum's recent newsletters have concentrated on reports that wildfires were causing less damage as a proportion of GDP than they used to, and that fewer people are dying from heat-related deaths, because there are more airconditioners. "Warmer weather is a lifesaver," the forum's head Benny Peiser wrote for The Conservative Woman blog last week. Nevertheless, Le Quere has some hope this wave of heat could lead to clearer thinking. "It is one possible positive outcome of what's happening now," she says. "It's slowly starting to sink in that what was done in the past is done; the only thing we can do is what we will do in the future.