Fatalism is contagious. By wringing their hands about the difficulty of making international agreements, the cost of technology, and public bolshiness, commentators, business people, and (privately) many politicians only encourage inertia about a problem that seems too far off to switch on the danger light in most brains.

Fatalists say we can only adapt, because global warming is too costly to curb. But you can’t “adapt” to a rise in sea level that could wipe out a third of Bangladesh in 30 years. Historically, species have adapted to climate changes by moving to more habitable regions. But on a crowded planet there is nowhere left to go. There are 120 million Bangladeshis. Will they be welcome in India? If the ice keeps melting at its present rate, I am told that Greenland will become habitable in between 1,000 and 5,000 years. By then there could be rather a long queue.

Climate change is a threat to national security. Two years ago, a study for the Pentagon concluded that America’s security could be jeopardised in as little as 20 years’ time because of instability caused by dwindling global food, water and energy supplies. Its authors are highly respected scenario planners who deal in uncertainty — and in human behaviour. For while academics and the Intergovernmental Panel on Climate Change debate the most critical developments that may occur in around 2050, human beings will react earlier. East Africa has seen a marked decline in annual rainfall for the past decade. India and China are already seeing heavier monsoon rains and longer drought periods. Punjab, once India’s breadbasket, is now half desert. China’s northern plains, which produce around two thirds of its grain, are shrinking. The water table is under threat. China has only 8 per cent of the world’s fresh water to meet the needs of 22 per cent of the world’s people.

If we are not careful, in the next 20 years aid budgets could be eaten up in helping countries to deal with the impact of climate change and with new sources of political instability. China needs to keep its enormous population placated with economic growth. Limit that growth and you have civil unrest. Continue that growth through fossil fuels, and you have head-to-head conflict looming with the US over oil supplies.

The science keeps moving on: and each new projection seems to put the tipping point nearer. That is the case with the ice sheets in Greenland and Siberia. We know that they are trapping a store of methane that is greater than all historical emissions of greenhouse gases put together.

At the British Association for the Advancement of Science meeting this week, Professor Eric Wolff described how the British Antarctic Survey has drilled two miles down to measure the concentration of gases in the atmosphere over a staggering 800,000 years. That is way before Man even thought of doodling on a cave wall. CO2 and methane have tracked temperature remarkably closely over that whole period: there has been no occasion in all that time when CO2 has increased without temperature following. These gases are now at levels that are unprecedented, and are rising at a spectacular, record rate. These ice cores show beyond doubt that humankind has changed the composition of the atmosphere.

This is great news. If the warming we have seen so far was “natural”, we would be in a real bind. If it is man-made, we have a chance to avert it. Despite all the bleating, we already have all the technologies we need to combat climate change: wind power, solar power, tidal power, carbon sequestration, nuclear power, microgeneration and energy efficiency (which alone could reduce rich world emissions by between 40 and 80 per cent, depending on whom you believe).

Yet the fatalists wildly overstate the costs of taking action. The British Government’s energy White Paper put the cost of stabilising atmospheric concentrations of carbon dioxide at 550 parts per million as the equivalent of 0.5-2.0 per cent of GDP in 2050. Paul Ekins, writing in The Energy Journal in 2004, calculated the net costs to the US Government of meeting Kyoto Protocol targets at no more than 1 per cent of GDP. Arnold Schwarzenegger does not think that his new plans for slashing emissions will cripple California; he thinks exactly the opposite.

So why are we so feeble in the face of all this evidence? Perhaps because global warming is not the kind of clear and present danger that human brains are wired to react to. It is difficult to mobilise people against something that is happening gradually. It is also difficult to mobilise people against an enemy that is invisible. In war we mobilise our resources against a visible enemy. With climate change, the villains and victims are the same people.

Fortunately, institutional wheels are beginning to turn. Sir Nicholas Stern, who is heading the Treasury’s review into the economics of climate change, is of the view that early intervention is preferable to a clean-up that could turn out to be too late. Countries and companies have started to trade carbon emissions, and are beginning to transfer cleaner technologies to China. Carbon taxes are being openly discussed in the corridors of power. A new charity, Global Cool, will soon be launched by people in the film and marketing industries who specialise in influencing consumer behaviour. A good thing, given that of all the barriers we face, the greatest is probably psychological. Let us not be dismissed by future generations as the people who had a chance but couldn’t face it.

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