LEADING ARTICLE : The green odyssey will not always be applauded

It's a rather heady feeling to wake up and find you are living in a paragon among nations, to hear your Prime Minister commanding the international stage and that hackneyed phrase "giving a lead" actually meaning something for once. Today Britain is up there with the good of the earth, plausibly urging other nations to mend their ways and follow the practical example of Britain in reducing carbon dioxide emissions, thinking afresh about energy use and public transport.

Let's not play the cynic and observe that Tony Blair's interest in environmentalism had not hitherto been large, unlike his Foreign Secretary's. Both the style and the substance of Mr Blair's address yesterday to the Earth Summit conference in New York were admirable. The science is now well established. Global warming is happening with demonstrably ill effects. Reductions in the emissions of greenhouse gases can be effected without revolutionary changes in public policy or private consumption. The British propositions for targeted reductions within a decade are practical. PS: Tony Blair's intention to make the next G7-plus-Russia summit more focused and businesslike is overdue and a tribute to this government's dislike of grandiloquence. The adjective "roundhead" has been bandied around in recent weeks, but if this instinct leads to international gatherings where there is more substantial discussion and less grandstanding (and dressing up in cowboy boots), let's hear it for Colonel Ironside.

For all that, the Government needs to watch it. For a Scandinavian country to instruct the world, as if from a pulpit, is acceptable; their international entanglements are few. They are small, unthreatening voices, and are reacted to as such.

We, though, are in a different category. Redundant they may be, but this country still possesses nuclear weapons. We have a large, export-orientated weapons and aircraft industry. It is not just that these have "environmental" consequences, it is that Britain's stock of international moral credibility is necessarily limited by history and current diplomatic posture - how much pressure, for example, are we going to bring through the Commonwealth on our kith and kin in the Antipodes if they take against taxes on aircraft fuel, something now being proposed with good reasons by the European Union? Britain likes to bask in the "special relationship" with the United States; how many overt attacks on American culture (of which we remain heavy consumers) will it take before American politicians and public start resenting the Brits?

Much environmentalism is fairly costless. Signing the bio-diversity treaty and forswearing rain-forest products is cheap enough, for us. It's when going green calls up increases in regressive taxes which hit the poor; when neo-liberal market solutions just don't work; when environmentalism entails heavy-handed intervention ... it's then that the Government runs its biggest risk in opening so ostentatiously its green flank.

There, in the darkness of the Tory back benches, sits John Gummer, a warning of the dangers. The man who went to the Rio Summit in 1992 amid such fanfare delivered only partially when he returned home; he was and is committed, but his cabinet colleagues proved mostly uninterested in the environmental dimensions of transport, housing and the fiscal system. It was not just Tory intransigence or a blind faith in the market. The problem for the Major government was the fickleness of public opinion. A chorus of approval greeted the decision last week to ban auto-cooling gadgets for soft drinks, which release large amounts of CFCs. The public will also give its approval to proposals to improve public transport and strengthen planning controls - and it was remarkable how little opposition greeted John Prescott's unilateral abandonment of the roads programme the other day. But we also like lowish taxes, running our own car(s) and ensuring our nephews and nieces get access to that new housing development out in the green fields. That is the public: how will green Mr Blair explain the huge tailbacks that will be caused by his millennium expo at Greenwich?

Already there are signs of politician's glibness on questions that touch basic, everyday and intractable behaviour, as when Mr Cook yesterday claimed he did not want to stop people using their cars ... all he wanted was to raise the quality of the alternative, public transport. It is an argument often heard in education - it is not a matter of banning private schools but bringing state schools up to par. It is a good argument, the only argument possible in a liberal society, but it is potentially hugely costly.

Environmentalism as a philosophy has a twisted and complicated origin in the history of ideas, first left then right. Nowadays, the green credentials of certain corporate chiefs notwithstanding, it has to be regarded as a left of centre affair. That is for one very good reason: it usually involves more rather than less government. Is this what Tony Blair and New Labour are really about: tolls and controls. A congestion tax is still a tax. One of Labour's ambitions in office is to recalibrate the relationship between citizen and state, between government and the governed. Seeing Tony Blair up there in the bright lights off Broadway might, temporarily, endear him and his colleagues to the public back home. But sooner or later, if Labour wants to accomplish half of what it promises, it is going to have to start telling the public some unpleasant things - like stop driving, pay more, consume less. Mr Blair's speech was a good start, but only a start, in preparing opinion in order to get such controversial decisions through. The words sounded good and were widely applauded. Some of the decisions that must necessarily follow them will be hated and booed.