Johann Hari: How I wish that the global warming deniers were right

Every day, I pine for the global warming deniers to be proved right. I loved the old world – of flying to beaches wherever we want, growing to the skies, and burning whatever source of energy came our way. I hate the world to come that I've seen in my reporting from continent after continent - of falling Arctic ice shelves, of countries being swallowed by the sea, of vicious wars for the water and land that remains. When I read the works of global warming deniers like Nigel Lawson or Ian Plimer, I feel a sense of calm washing over me. The nightmare is gone; nothing has to change; the world can stay as it was.

But then I go back to the facts. However much I want them to be different, they sit there, hard and immovable. Nobody disputes that greenhouse gases trap heat in the atmosphere, like a blanket holding in the Sun's rays. Nobody disputes that we are increasing the amount of those greenhouse gases in the atmosphere. And nobody disputes that the world has become considerably hotter over the past century. (If you disagree with any of these statements, you'd fail a geography GCSE).

Yet half our fellow citizens are choosing to believe the deniers who say there must be gaps between these statements big enough to fit an excuse for carrying on as we are. Shrieking at them is not going to succeed.

Our first response has to be to accept that this denial is an entirely natural phenomenon. The facts of global warming are inherently weird, and they run contrary to our evolved instincts. If you burn an odourless, colourless gas in Europe, it will cause the Arctic to melt and Bangladesh to drown and the American Mid-West to dry up? By living our normal lives, doing all the things we have been brought up doing, we can make great swathes of the planet uninhabitable? If your first response is incredulity, then you're a normal human being.

It's tempting to allow this first response to harden into a dogma, and use it to cover your eyes. The oil and gas industries have been spending billions to encourage us to stay stuck there, because their profits will plummet when we make the transition to a low-carbon society. But the basic science isn't actually very complicated, or hard to grasp. As more carbon dioxide is pumped into the atmosphere, the world gets warmer. Every single year since 1917 has been hotter than 1917. Every single year since 1956 has been hotter than 1956. Every single year since 1992 has been hotter than 1992. And on, and on. If we dramatically increase the carbon dioxide even more – as we are – we will dramatically increase the warming. Many parts of the world will dry up or flood or burn.

This is such an uncomfortable claim that I too I have tried to grasp at any straw that suggests it is wrong. One of the most tempting has come in the past few weeks, when the emails of the Hadley Centre at the University of East Anglia were hacked into, and seem on an initial reading to show that a few of their scientists were misrepresenting their research to suggest the problem is slightly worse than it is. Some people have seized on it as a fatal blow – a Pentagon Papers for global warming.

But then I looked at the facts. It was discovered more than a century ago that burning fossil fuels would release warming gases and therefore increase global temperatures, and since then, hundreds of thousands of scientists have independently reached the conclusion that it will have terrible consequences. It would be very surprising if, somewhere among them, there wasn't a charlatan or two who over-hyped their work. Such people exist in every single field of science (and they are deplorable).

So let's knock out the Hadley Centre's evidence. Here are just a fraction of the major scientific organisations that have independently verified the evidence that man-made global warming is real, and dangerous: Nasa's Goddard Institute for Space Studies, the US National Oceanic and Atmospheric Administration, the UN's Intergovernmental Panel on Climate Change, L'Academie des Sciences, the Indian National Science Academy, the US National Academy of Sciences, the Deutsche Akademie der Naturforscher Leopoldina, the UK's Royal Society, the Academia Brasileira de Ciencias, the Chinese Academy of Sciences, the Russian Academy of Sciences, the US Environmental Protection Agency... I could fill this entire article with these names.

And they haven't only used one method to study the evidence. They've used satellite data, sea level measurements, borehole analysis, sea ice melt, permafrost melt, glacial melt, drought analysis, and on and on. All of this evidence from all of these scientists using all these methods has pointed in one direction. As the conservative journalist Hugo Rifkind put it, the Hadley Centre no more discredits climate science than Harold Shipman discredits GPs.

A study for the journal Science randomly sampled 928 published peer-reviewed scientific papers that used the words "climate change". It found that 100 per cent – every single one – agreed it is being fuelled by human activity. There is no debate among climate scientists. There are a few scientists who don't conduct research into the climate who disagree, but going to them to find out how global warming works is a bit like going to a chiropodist and asking her to look at your ears.

Part of the confusion in the public mind seems to stem from the failure to understand that two things are happening at once. There has always been – and always will be – natural variation in the climate. The ebb from hot to cold is part of Planet Earth. But on top of that, we are adding a large human blast of warming – and it is disrupting the natural rhythm. So when, in opinion polls, people say warming is "natural", they are right, but it's only one part of the story.

Once you have grasped this, it's easy to see through the claim that global warming stopped in 1998 and the world has been cooling ever since. In 1998, two things came together: the natural warming process of El Nino was at its peak, and our human emissions of warming gases were also rising – so we got the hottest year ever recorded. Then El Nino abated, but the carbon emissions kept up. That's why the world has remained far warmer than before – eight of the 10 hottest years on record have happened in the past decade – without quite reaching the same peak. Again: if we carry on pumping out warming gases, we will carry on getting warmer.

That's why I won't use the word "sceptic" to describe the people who deny the link between releasing warming gases and the planet getting warmer. I am a sceptic. I have looked at the evidence highly critically, desperate for flaws. The overwhelming majority of scientists are sceptics: the whole nature of scientific endeavour is to check and check and check again for a flaw in your theory or your evidence. Any properly sceptical analysis leads to the conclusion that man-made global warming is real. Denial is something different: it is when no evidence, no matter how overwhelming, could convince you. It is a faith-based position.

So let's – for the sake of argument – make an extraordinary and unjustified concession to the deniers. Let's imagine there was only a 50 per cent chance that virtually all the world's climate scientists are wrong. Would that be a risk worth taking? Are you prepared to take a 50-50 gamble on the habitability of the planet? Is the prospect of getting our energy from the wind and the waves and the sun so terrible that's not worth it on even these wildly optimistic odds?

Imagine you are about to get on a plane with your family. A huge group of qualified airline mechanics approach you on the tarmac and explain they've studied the engine for many years and they're sure it will crash if you get on board. They show you their previous predictions of plane crashes, which have overwhelmingly been proven right. Then a group of vets, journalists, and plumbers tell they have looked at the diagrams and it's perfectly obvious to them the plane is safe and that airplane mechanics – all of them, everywhere – are scamming you. Would you get on the plane? That is our choice at Copenhagen.

Johann recently traveled across a melting Arctic. To read his report of the journey, click here.

j.hari@independent.co.uk