John Rentoul: Against all odds, a step up for the planet

The global commitment to tackle climate change will make a difference. It would not have happened without a clutch of Blairites

One of my hobbies is collecting. And one of the things I collect is Questions to Which the Answer is No. Preferably questions laden with significance in Daily Mail headlines, which carry the implication that the answer is affirmative but for which the newspaper knows it has no evidence. A recent one was: "Could Lord Mandelson become Prime Minister?" One of my favourites was "Is this Atlantis?" in The Sun, reproducing a Google Earth picture of the seabed near the Azores. A Google spokesman was quoted a few days later, explaining that the apparent grid of straight lines reflected the path of boats as they gathered data from the sea floor.

Last week's addition to my collection was the heading on a full page of analysis in The Independent: "Will it really be possible to meet the G8's climate change targets?" To which the honest answer is: "Of course not." And yet I must say, as someone who would like the answer to be "Yes", that last week's summit in Italy was a triumph.

How so? Because climate change is such a big problem, requiring an act of collective will by billions of people, most of whom have more immediate worries. There is no hope of a complete or perfect solution to it. Indeed, climate change is already happening and a lot of future global warming has already been locked into the system, given that the burning of carbon fuels is not going to stop this year or next. The only thing that can happen, therefore, is a chaotic interplay of attempts to reduce – too late – carbon use and to adapt – too late – to a warmer climate, and this at a point when other human pressures on the planet's resources are becoming chronic.

It was, therefore, a great achievement to secure a preliminary agreement among the richest countries to make deep cuts by the middle of this century. The target of an 80 per cent cut won't be met, and, even if it were, the average global temperature is likely to rise by more than the C target also agreed as the upper limit of tolerable change. But some kind of reduction is likely, and it will be greater and earlier than it would have been if last week's deal had fallen through.

However insufficient any reduction is, it will still make it easier for future generations to cope with the environmental crisis we have bequeathed them. That is why it is worthwhile, but it is a triumph because, until recently in the long history of world summitry, it seemed so unlikely. It now seems probable that a meaningful global carbon-reduction deal will be reached at the mother of all green summits in Copenhagen in December.

That is why optimism is such a precious commodity, even, or perhaps especially, when it seems slightly ridiculous. Because it is a ludicrous notion: that all humanity could unite in a common enterprise of this magnitude. The serious objection to trying to achieve it comes not from those who deny the science of climate change – whose cultish tendency is likely to intensify as the evidence accumulates – but from those who say it can't be done without a world government, or at all.

So how did it happen? The big change is President Obama. Obviously. He can do no wrong. He still enjoys a 58 per cent favourable rating in US Gallup polls, and is even more popular in the rest of the world. But it was a small triumph also for Gordon Brown. And, unlikely as it may seem, for three other British leaders. It may seem strange to give any credit to a prime minister so reviled at home, especially one who appears to show so little interest in green issues. And it may seem parochial to wonder about the contribution of British politicians at all to such an endeavour, representing as they do a country that is responsible for such a small share of global emissions.

But it is not ridiculous to say that David Miliband, his brother Ed and, above all, Tony Blair have contributed as much as anyone to last week's milestone. Climate change was barely on the agenda for international summits until Blair put it there at the Gleneagles G8 in 2005. Since then, Britain's record as an exemplar has been mixed. But the Miliband brothers have achieved much. First David at Environment and now Ed at the new department of Energy and Climate Change – created by Brown last year although, as David said last week, Blair should have created it in 1997. As one observer put it, referring to their father, Ralph Miliband, the Marxist historian: "They are the sons of the Enlightenment. For them, a Problem with a capital P requires the application of Reason with a capital R to produce a Solution with a capital S. The trouble is that this doesn't take into account chaos and evil."

But they have passed a Climate Change Act, with Conservative support, that commits Britain to the most ambitious short-term target of any country in the world, of a 34 per cent cut in emissions by 2020, only 11 years away. Ed Miliband has produced a policy for clean coal power that is an example to the world, and a plan for the biggest wind farm in the world, the London Array in the Thames Estuary, to start operating in 2012.

Britain's record is not perfect, and chaos and evil will intervene. But if rich countries need to lead by example, we can be proud enough. Was it worth it? That is a question to which the answer is Yes.

John Rentoul's blog is at independent.co.uk/jrentoul