Britain’s Energy and Climate Change Secretary, Ed Miliband (the former Nation intern who said that we need a mass movement to push for action on the environment), has just published a hugely ambitious plan to cut Britain’s carbon emissions by 34% in the next decade, working towards 80% by 2050. The target is non-negotiable; it was voted into law last year. But until now, nobody had a clear idea of how we were going to get there.

Miliband’s plan is based, as he puts it, on "green hope, not green despair." Its first step is to return control of the power grid to the government, which will allocate connections to producers of renewable energy. Forty percent of Britain’s electricity will come from wind, tidal and nuclear sources–and the nuclear share will fall from 13% to 8%, in spite of lobbying by the Confederation of British Industry. The government itself will be put on a tight carbon budget; energy companies will have to invest in home insulation; there will be subsidies for low carbon vehicles. Energy prices will increase, but with Britain’s North Sea oil and gas running down that would happen anyway. Miliband predicts the creation of 400,000 new green jobs; Prime Minister Gordon Brown has hailed his plan as the engine that will drive economic recovery. Two hundred years ago Britain gave birth to the industrial revolution’s dark satanic mills; the hope is that our boffins can now lead the world to a clean green Jerusalem.

Of course there are fudges, caveats and plenty of stumbling blocks. The government plans to go ahead with new coal-fired plants on the gamble that carbon capture technology will be viable in the next few years; it also intends to press on with the controversial third runway at London’s Heathrow Airport. Miliband is right to say that going green shouldn’t mean wearing sackcloth and ashes, but there is political expedience as well as class solidarity in his support for cheap air travel for working people. The projected increase in wind-generated power will mean more giant turbines towering over rural landscapes and bitter arguments over where they should go. The Severn Barrage, which would harness the tides between England and Wales, is opposed by many of the big conservation groups. And the whole plan’s sheer ambition and expense is daunting–though climate scientists say it doesn’t go nearly far enough.

But this is the first detailed plan by any government to move away from fossil fuels and make deep cuts in emissions–and it’s broadly supported by the Conservatives and the Liberal Democrats as well as the Labour Party. Whether or not it works in every detail, it represents the kind of creative, connected thinking we need on climate change. It makes one almost hopeful for the upcoming climate summit in Copenhagen.