WHAT a week. The government of California took leading car manufacturers to court for manufacturing polluting vehicles; Richard Branson said he would plough the proceeds of his various transport interests into renewable energy; we learned that the Arctic is melting so fast it’s possible to sail to the North Pole; and the Tyndall Centre for Climate Change research said we would have to cut CO2 emissions by 90% by 2050 to avert catastrophe.

What does all this have to do with Gordon Brown? Everything. Assuming he makes it to Number 10, climate change is the issue that will dominate his administration. Brown will have to be green. Management of the environment will dominate all democratic politics over the next two decades.

And there seems little doubt it is Brown whom history has chosen to address this problem. Friday’s Guardian/ICM poll may have shown him trailing the Tory leader, David Cameron, in personal character, but that’s hardly surprising after a month of Brown’s own colleagues, ex-Labour ministers among them, accusing him of “back-stabbing” “stupidity” and “psychological flaws”.

But when people start to consider who they want to run the country, and who they want to deal with the massive challenges ahead, it seems likely they will agree with the vast majority of the Labour Party that Gordon Brown is the only politician around with the experience, intellect and confidence to meet the demands of the times.

Like him or loathe him, Brown is simply the most substantial politician of his generation. The longest-serving and most successful chancellor in 200 years, an international figure who is able to win the support of everyone from the IMF to Make Poverty History. John Reid and Alan Johnson are also-rans even before the race has begun.

The chancellor is an internationalist, a moralist and a ‘do’-er. He revels in complexity and big projects, and in addressing the great ethical issues of the times, as he showed over the G8 anti-poverty drive. Climate change is the biggest and most complex problem around. And it’s happening now.

There is a marked change in public attitudes taking place, as the success of Al Gore’s film An Inconvenient Truth has indicated. Even in America, home of climate-change denial, 70% of the population now accepts that climate change is happening, according to the polling organisation Zogby. The science of climate change has never really been in doubt, but the various commercial forces which sought – like tobacco manufacturers in the 1950s – to sew doubt are on the run. There will soon be nowhere left to hide .

The recriminations have already begun. The public are going to be very, very angry and will want to find out who is to blame. I would not like to be on the boards of big oil, car or power companies in the next 20 years. Not only will their stock be worthless, they could become the target of mass litigation. Airline boss Richard Branson may be protecting his own back.

An entire generation of politicians also stands accused of fiddling while the world burned. Governments pursued profligate energy policies when their own advisers, such as Sir David King, the chief scientific adviser, had been warning them that the carbon economy was killing us. They will have to unlearn their habits of spin, short-termism and consumerism.

Gordon Brown realises the people behave best when they are faced by a great challenge and common purpose. The second world war brought an entire generation together, across class boundaries, and created the moral climate for the creation of the National Health Service, which Brown loves. The challenge of climate change is greater than any in human history.

When there is a common moral goal, a lot of political problems disappear. The new climate-consciousness will make it very much easier to deal with problems such as transport and housing. People will accept limitations on their freedoms when they accept the moral and social purpose of them. Restrictions on car use, smaller houses, higher heating bills and reduced foreign travel will be relatively easy to achieve once people accept the reality of the situation.

As Al Gore points out in An Inconvenient Truth, the means to reduce CO2 emissions are already to hand. The technology is not complex; it just needs the political will. As it happens, Britain is rather well adapted to the new kind of post-carbon economy. We don’t have a mass car industry for a start.

Scotland has 25% of Europe’s wind and tidal energy, and we have an excellent record of developing renewable technologies – though unfortunately we have a habit of handing the development of them to other countries.

Brown could use climate change to address a whole series of domestic problems, such as congestion and the housing crisis. What about a network of fast rail links, bringing Scotland and England closer together, and integrating our economy with the rest of Europe? This would greatly reduce dependency on motor transport. Tesco is already shifting freight to rail.

The costs of heating and insulation will inevitably bring house prices in Britain back to earth. But the economy needn’t crash with them. What will be needed is a national programme for building smaller, affordable, energy-efficient housing units, using micro-generation for power to replace Britain’s out-dated housing stock.

So, greening Britain could actually promote economic development and bring together a number of strands of Brown’s policy agenda. The chancellor will have noticed the favourable response to Liberal Democrat leader Sir Menzies Campbell’s new green taxes unveiled last week. Brown has been toying with the idea of switching the burden of taxation from income to pollution. I suspect he might lift a lot of the LibDem ideas wholesale.

Green taxation might even provide the theme for any Labour-LibDem coalition after the general election in 2009. It is becoming clear that Labour is unlikely to win an overall working majority, and reducing CO2 could be the basis for cooperation across parties. Brown could even challenge David Cameron to put his money where his mouth is and back an agreed programme of infrastructural and taxation changes aimed at ending carbon incontinence.

Cometh the hour, cometh the man. You can readily imagine Brown at global events with Al Gore and Bill Clinton, announcing the creation of institutions designed to meet the challenges of climate change. It’s going to happen, and Brown is up for it. People were wondering what replaced socialism. This may be it.