Almost all the discussion of climate change up to now has been about "mitigation" - in other words, how to prevent it from happening. But prevention, although important, is not enough. Climate change is going to happen, and we need to think more about adapting to it.
The issues raised by climate change are particularly intractable. For instance, the prospect of climate change tests to the limits the extent to which people today will give up quality of life for the benefit of future generations - and of people in other countries. Moreover, whereas the damage done by climate change could be huge, the costs of taking action to avoid it will definitely be enormous. Just reflect on the fact that oil today costs more than $70 a barrel - the equivalent of a tax that no politician would have dared to suggest when the Kyoto Protocol was negotiated - and yet our roads are still crammed with cars and our skies with planes.
In addition, this is an international problem - not a national one. But climate change will affect different countries in different ways. It will be harsh for India and sub-Saharan Africa. But a sunny Siberia might delight Russia. If swathes of Arctic ice melts, it will be easier to extract the oil and gas reserves - perhaps one-quarter of the world's remaining buried stocks, much of them on Russian territory.
So striking a global deal will be difficult. It is not a question of persuading America to sign up to Kyoto - it won't - or even of extending that largely ineffectual agreement. It will take extraordinary diplomacy and ingenious mixtures of threats and rewards to persuade the main protagonists to reach agreement.
Moreover, even with the best will in the world, we do not yet have the technology to prevent global warming from occurring. A recent study by the International Energy Agency reckoned that the speedy introduction of best practice in energy conservation and in substitutes for fossil fuels would not be enough to prevent some continuing rise in the atmospheric concentration of greenhouse gases.
The trouble is, our living standards are inextricably related to our use of energy, and especially to fossil fuel. Of course, we can increase energy from renewables such as wind and solar power. But these account for about only 2 per cent of world electricity generation today - whereas coal accounts for about 40 per cent. Coal will dominate, especially in China and India, for the foreseeable future. Carbon capture and storage is going to be essential here, but the technology has hardly begun to be used commercially.
Energy conservation could reduce the prospective rise in emissions more sharply than any other known technology. But the lags are long: many of the technologies we use today were invented a century ago.
So some climate change looks likely to occur, whatever we do. We should therefore think more about adapting to hotter weather. Adaptation sounds brutal: and indeed meaningless, if you live in Bangladesh. But we need to think now about policies that prepare for a warmer world.
What might they be? Flood defences and tough rules about building on flood plains are obvious; so is better insulation against heat as well as cold, and more covered and sheltered spaces in public areas, to protect against both the sun and the probability of more rain. Developing countries will need crops and trees that will thrive in hotter temperatures and drier conditions - that should be a research priority for aid agencies. And species such as plants and trees will need protected corridors running north-south along which they can spread to move away from insupportably warm weather.
Adaptation policies have big advantages. They can be pursued at a national - indeed, at a local level - and so will involve far less complex international negotiation. They will require good public policies, but a great deal of adaptation will happen in any case, and largely through the private sector: no government mandate boosted sales of fans and air conditioning as temperatures soared this summer. Of course, there are important areas where no adaptation is possible - we cannot relocate the Amazon or insulate coral reefs. But governments could and should put in place an adaptation strategy right away.
We should not abandon attempts to slow global warming. The danger of disruptive change will increase, the greater the atmospheric concentration of warming gases. But we should equally not pretend that we can prevent climate change. It's going to happen, and we need to be ready for it.
The writer is president of the British Association for the Advancement of Science, and Rector of Exeter College, Oxford UniversityReuse content