Leading article: Cameron's green edge

Global warming was supposed, a little over a year ago, to be a cornerstone on which Tony Blair was to rebuild his battered international reputation. By putting it at the heart of the Gleneagles summit of the world's most powerful leaders, he drove it up the international agenda. Just for once, by venturing to stand up to George Bush, he even managed to get the President to give a little ground. But like so many of his worthy efforts, his initiative proved to be a flash in the pan. Soon he was back in default mode, abjectly aping his Texan mentor in decrying the need for international targets to cut pollution, and insisting that technological progress will magically solve the problem. Instead it has been David Cameron who has used the issue of climate change to make the political weather.

Writing in The Independent on Sunday today, the Tory leader outlines his plans for legislation to lay down binding "year on year targets" for cutting Britain's emissions of the greenhouse gases that cause global warming. On Friday, in an unprecedented move with Friends of the Earth, he launched a push to get the Government to adopt the scheme. These are just the latest steps in a steady, if surprising, progress that began almost a year ago, just as the Prime Minister's short-lived courage on the issue failed.

On the very day that Mr Blair publicly doubted the value of a new climate change treaty, Mr Cameron put forward in The Independent the most radical measures to tackle global warming ever proposed by a leading British politician. Then he was still a leadership candidate. When he won, he focused on the issue both in his acceptance speech and in his first Prime Minister's Questions, and, within days, recruited the radical environmentalist Zac Goldsmith to help lead a review of Conservative policies. At the same time he appointed Peter Ainsworth, probably the most respected green politician in parliament, as his Environment spokesperson.

Most commentators - and many Conservatives - have failed to understand how well this has worked for his party, both by demonstrating how much the Tories are changing and by tapping into a popular issue, hitherto largely neglected by the political establishment. Even green Tories were nervous when he decided to make the environment the centrepiece of this summer's local election campaign. Commentators laughed when he dramatised it by visiting the Arctic, but it helped him win, and win handsomely. Now, as the new political season begins, senior colleagues, from Mr Goldsmith to George Osborne (perhaps the least environmentally friendly of his inner circle), have defied cynics, putting the environment at the top of the party's priorities again, stressing its commitment to environmental taxation and "green growth".

It is a good start. Green taxes hold huge potential for cutting pollution and creating jobs, by shifting the fiscal burden from employment to waste. And the Conservatives are right to realise, as Mr Cameron writes today, that protecting the environment and promoting growth are not necessarily "at odds", and should be complementary. The new technologies that will be needed to save energy, produce it from clean sources and cut pollution are likely to prove a powerful stimulus to growth, while providing many more jobs than the dirtier ones they replace. Mr Blair and his ministers also claim publicly to grasp this point, but in private the Prime Minister still betrays his real opinion that green measures harm the economy.

Mr Cameron and his aides need to work out the detail of what green growth means. They should not shrink from spelling out that - while benefiting the economy overall - it will entail lifestyle changes, such as a new emphasis on public transport at the expense of Margaret Thatcher's "great car economy". If they do, they will gain even more support. The public is yearning for credible leadership on the issue, something that despite the ludicrous message on the mug that Tony Blair flourished last week, he has signally failed to provide.