Leading article: A rare flash of hope on a gloomy horizon

This is what the Liberal Democrat environment spokesman, Norman Baker, proposes today. Mr Baker argues that there should be an annual, independent audit of Britain's carbon emissions. This should be recognised and supported by the three main political parties. Such an audit should also have the authority to require governments to implement reductions in emissions every year, depending on the rate of progress made. Friends of the Earth have long advocated such a scheme.

The good news is that Oliver Letwin, the Conservative environment spokesman, has come out in support of the Liberal Democrat proposal. Now all that is required is the assent of the Government, and Britain will have a ground-breaking cross-party commitment to reduce emissions every year, without fail.

This is a rare flash of hope on an increasingly gloomy horizon. Bad news on the state of our planet's climate has been emerging for some time. Some of the most dramatic images of 2005 have been of disappearing polar ice. Satellite photographs from Nasa show the melting of the polar ice pack is accelerating. It has shrunk by 30 per cent since 1978 and caused the warmest arctic winter for 400 years. The natural patterns of Earth are undeniably altering. The effects of this on natural life are already beginning to manifest themselves. The livelihoods of the Inupiat Eskimos of Alaska look like they will be the first to be destroyed. But the catastrophe hangs over the heads of thousands more communities. Animal life is under ever greater threat. Research commissioned by the Department for Environment, Food and Rural Affairs has found a wide range of changes in wildlife migration patterns in response to global warming.

Britain has a reputation for being a world leader on global warming. It is a reputation that looks increasingly ill deserved. The UK's C02 emissions have been rising for the past three years. Britain now emits more carbon dioxide than in 1997, when Labour took power. The Government is set to miss its target of reducing emission levels by 20 per cent from 1990 levels by 2010.

And now we have a Prime Minister who, astonishingly, appears to be changing his mind about the urgency of the threat. Last month, Mr Blair declared:"I'm changing my thinking about this". He now, apparently, backs the Bush administration's argument that technology-led solutions, rather than emission caps, are the way to deal with climate change. No one would seek to deny green technology must play a vital part in reducing global warming, but it is folly to suggest serious progress can be made without internationally-agreed limits on C02 emissions. The world needs a stricter and more ambitious follow-up agreement to the Kyoto Protocol. The climate-change pact signed in July by the US, Australia and four Asian countries offers no long-term solution.

The beauty of the idea proposed by the Liberal Democrats today is that British ministers, at least, would be locked into doing the right thing. Those populist opposition politicians who argue against emission-reduction measures on the grounds that it would damage Britain's economic competitiveness would have the ground cut from underneath them. This proposal has the potential to trigger much more rapid progress than we have seen in this vitally important area. And if it succeeds, it could be a model for the rest of the world to follow.