Freak weather raises climate change debate When Phillip Dugaw decided to escape the sweltering heat at home in Washington DC last weekend and fly down to the beach in South Carolina, he had no reason to expect anything odd. But when the pilots in the US Airways plane the 24-year-old consultant boarded at Ronald Reagan National Airport on Friday afternoon tried to taxi to the runway, the aircraft would not budge. "They told us it looked as if the plane got parked in a bit of a rut," Mr Dugaw told the Financial Times. In fact, the plane had made its own rut. With the temperature hovering around 100 degrees Fahrenheit in the record-shattering heatwave baking much of the US that week, its wheels had sunk several inches into softened asphalt. The passengers were unloaded, along with their luggage, so it could be shifted, which as Mr Dugaw says, is not the sort of thing one expects to see in the capital of the United States. In the UK, meanwhile, the wettest April-to-June period ever recorded has already blighted the Queen's diamond jubilee river pageant on London's Thames, marred the British Grand Prix, and killed off a Hyde Park Kylie Minogue and Jason Donovan reunion concert. Now, barely half way through July, some parts of the country have already had more than 250 per cent of their average rainfall for this month, and a darker fear is forming: that rain could wreck the London Olympics opening ceremony on July 27. If unusual weather strikes two of the world's media capitals simultaneously, it is no surprise to see yet another debate about whether it is odd but naturally occurring, or whether climate change is to blame. This time, however, the terms of that debate may have shifted. Scientists have been generally reluctant to suggest a connection between global warming and a specific flood or heatwave. But on Tuesday researchers at the UK Met Office and the US National Oceanic and Atmospheric Administration released a report concluding a link could be drawn between global warming and some of last year's extreme weather events. Climate change had boosted the odds of both the Texas drought and the unusually warm UK November occurring by around 20 and 60 times respectively, compared with the 1960s, the report said. One editor of the study, the UK Met Office's Dr Peter Stott, said it was still impossible to say for sure if the latest bout of extreme US weather was caused by climate change, but "the chances of having such heat waves have increased significantly." He added: "It's like loaded dice. The chances of throwing a six have gone up a lot and we're throwing a six in America at the moment. In the UK, the bewildering amount of apparently endless rain has led to the door of researchers such as Professor Jennifer Francis of Rutgers University in the US. She studies the fast-changing climate in the Arctic, where she says the average thickness of ice floating on the ocean has shrunk from around 3m in the early 1990s to between 1m and 1.5m. Her work suggests this could be affecting the northern polar jet stream - fast-moving rivers of air several miles high that race from west to east around the northern hemisphere and push around weather systems. The jet stream is driven by the difference in temperature between the colder polar region and warmer latitudes further south. But with that temperature difference shrinking as the Arctic warms, it may make the jet stream weaker and more meandering, effectively "blocking" wet or hot weather patterns, and causing extreme weather. "It's all about these patterns moving much more slowly and whatever pattern you happen to be in is the one that you're going to be stuck with for a while," says Prof Francis. So could there be a link between what is happening in the Arctic and the weird US and UK weather this month? "We're seeing a lot more of this kind of behaviour occurring and so it's getting harder and harder to say that it's not related to climate change and especially the change in the Arctic," she says. Still, some scientists remain wary of linking individual extreme weather events with climate change, in the way the authors of Tuesday's study have done. "My view is to some extent they're asking the wrong question," says Professor Michael Mann. He is the Penn State University scientist whose work on the contentious 1990s "hockey stick" graph linking an uptick in global temperatures with the start of the fossil-fuel-burning industrial revolution put him at the forefront of the climate wars. The climate is clearly changing, he says, pointing to US data going back several decades that show the ratio of warm weather records being broken compared with cold weather ones shifting to two-to-one in the last decade. But he likes an analogy coined by US researchers who compare the climate's effect on odd weather with a baseball player on steroids hitting a lot of home runs. "Clearly many of those home runs in a statistical sense are coming from the fact he took steroids, but you'd be asking the wrong question if you were to take any one of those home runs and say, "Can you prove that this home run was due to him taking steroids?,"" he says. As long as it's framed properly I think it is appropriate to talk about the relationship that climate change does have with this unprecedented heat we're seeing this summer, because it's part of a pattern. It's not just this summer, it's this year, this decade and it's not just the US. The entire globe is warming up.