THE storm is calmed, the waters are receding, mostly, and all that is left is clearing up the mess. If only it were that simple. If this really is the start of climate change, a geography professor told me, there is nothing we can do about it. What feels to us like extreme weather will now be normal for at least two decades.

If this sounds apocalyptic, and a recipe for just going down the pub, he adds the rider: "All we can do now is stop it getting worse."

Climate change has been the dogma that has not barked in the deluge of media coverage of the floods. Two weeks ago, I asked elsewhere why, in the face of all this "global weirding", as one climatologist calls it, few people were talking about global warming.

Climate-change-deniers always insist that you cannot prove a causal link between one spell of extreme weather and global warming. That is true, just as you cannot link one specific cigarette to a smoker's developing lung cancer. But trends are another matter.

This week, Lord Stern, who wrote a seminal report on climate change in 2006, noted that four of the five wettest years ever recorded in the UK have occurred since 2000; so have the seven warmest years. That is only in Britain. Australia has just had its hottest year on record. North America has been gripped by a polar vortex. Bangladesh has had two once-in-a-lifetime cyclones in three years. The Philippines has had its worst-ever typhoon.

Common sense suggests that global warming should make the weather warmer here. But common sense, as so often, is wrong. Scientists warned years ago that the first change the UK should expect is more rain and wind, since a warmer atmosphere holds more water and more energy, which means more floods. QED.

Looking back, Lord Stern says, his verdict should have been harsher in 2006. "Since then, annual greenhouse-gas emissions have increased steeply, and some of the impacts, such as the decline of Arctic sea ice, have started to happen much more quickly," he says.

The Intergovernmental Panel on Climate Change concludes that the available scientific evidence suggests that it is 95 per cent likely that most of the rise in global temperatures is due to greenhouse gases, deforestation, and other human activities (Comment, 27 September; News, 4 October). "Inaction could be justified only if we could have great confidence that the risks posed by climate change are small," Lord Stern says. "But the risks are huge."

I know Nick Stern well. He and I were co-authors of the report for Tony Blair's Commission for Africa. He is a punctilious and naturally cautious man, with a great concern for academic accuracy. For some to see him an alarmist prophet of doom is a measure of how deeply rooted our ostrich scepticism is.

There are none so blind as those who will not see. The Prime Minister this week advised people in Upton on Severn to speak to "the man upstairs" about the floods. But prayer is not a sufficient answer. God helps those who help themselves, as my grandmother used to say.

If what we are seeing around us is the result of a two-degree rise in global temperatures, what can we expect from the four-degree rise that many scientists say is inevitable, unless we cut carbon emissions? Mass migrations, conflict, and war, Lord Stern suggests. The last time the global temperature was five degrees different from today, the earth was gripped by an ice age. We cannot say that we have not been warned.

Paul Vallely is Senior Research Fellow at the Brooks World Poverty Institute at the University of Manchester.