This weekend I stood in the park at Blenheim Palace and marvelled at the vision of Capability Brown, the landscape designer who knew that he would never live to see the full promise of the beauty he planned so meticulously. He was part of a century of people who were proud to leave a legacy of railways, bridges, and good governance to benefit others. Today future generations figure in government thinking primarily as suckers who will foot the bills tomorrow for political kudos today — fatter pensions to public servants, or hospitals and schools that are being built with debt that must be repaid in 30 or 50 years.

The generation that is in power today has benefited enormously from the vision of those who risked their lives in the 1940s, and who forged a welfare state to benefit those who came after them. Yet the politicians of this generation seem strangely prone to dodge long-term decisions. Criminals bursting from overcrowded prisons? Tell judges to release them. New rail links? Commission another feasibility study. Power stations nearing expiry? Consult. Such investments do not pay off within a five-year political cycle.

This is depressing enough at the best of times. But the emergence of climate change as a serious threat makes it intolerable. For most politicians, climate change creates an uncomfortable cognitive dissonance. They go into an absolute spin when urged to protect future voters from harm caused by voters today. While Britain under Tony Blair has arguably led the world in facing up to climate change, our own emissions have risen by 6 per cent since 1997. His Government has been too timid to even take the simple decisions of energy policy.

Yet some of today’s voters are waiting to be asked to do their bit. Some express it in polls that have altered dramatically in the past year, with more than half saying in an ICM poll last November that they would pay more in tax if it helped to combat global warming. Some express it through the Liberal Democrats, a proxy green vote if ever there was one. Many would willingly support an intelligent collective endeavour to reduce fossil fuel consumption, though not some hellish bureaucratic muddle.

Some environmentalists talk wistfully of “world government” to get round these problems. It is true that a dictatorship did once create the world’s most effective environmental policy — the “one child” policy in China. Most of us would rather be free to take our chances. But China today has little financial interest in combating climate change, sitting as it does on such a substantial proportion of the world’s coal reserves. We will have to help to make it worth China’s while.

Money is already flowing from the West to clean up the East, under the EU’s emission trading scheme (ETS). It is ironic that the EU member states, determined to show up the US, have used the American cap-and-trade model to create the most free-market solution to climate change possible. The idea is brilliant. Companies are given permits to pollute, which they can sell if they do not need them. This puts a price on pollution, which rises as the number of permits is gradually reduced. It creates a market in carbon. The same system has helped to eradicate sulphur dioxide from American factories, and it provides the best hope of reducing our dependence on fossil fuels.

The trouble is that the politicians who set the framework are so weak. Many have given out far too many permits to favoured companies, making the carbon price ludicrously low. Today and tomorrow in Berlin, EU leaders are expected to agree tighter targets. But only until 2012. If companies are to make big investments in low-carbon technology, permits must be auctioned, and over a much longer time frame.

The good news is that a little regulation can go a long way. The very existence of the ETS has brought to life the Chicago Climate Exchange, a carbon market that is entirely voluntary. Astonishingly, all sorts of utilities and companies, from Ford to Intel, have agreed to curb their emissions and to trade permits as if it was mandatory.

The very threat of regulation has made them keen to get a head start. And now that the McCain-Lieberman Bill to curb emissions has become the McCain-Lieberman-Obama-Clinton Bill, it seems likely that their expectations will prove correct.

Politicians may dearly love to leave it all to “the market”. But energy markets have always been regulated. The carbon market cannot prosper unless politicians keep tightening the cap. And companies will only look as far ahead as politicians are willing to. But it should not be impossible for politicians to take a longer-term view. For climate change is really a national security issue, not a party political one. The French have had a deep cross-party consensus for years on nuclear power and rail investment. This should not be beyond other nations to emulate.

Sir Nicholas Stern has described climate change as “a major disruption to economic and social activity on a scale similar to those associated with the great wars and the economic depression of the first half of the 20th century”. All the evidence suggests that intelligent investment now could avoid irreversible damage being done later.

Yet when capital has never been cheaper, and we have never been richer, far too little capital is flowing into a low-carbon future. The war against climate change will require some brave gambles from today’s politicians. When they are asked “What did you do in the war, Daddy?”, they would like to answer with pride.

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