The problem is simply stated. As Gordon Brown - discussing what he perceives to be an improvement in his political fortunes - says, "an hour is a long time in politics". It used to be a week, but everything is speeding up. To remain in office or to remain in business, decision-makers must privilege the present over the future. Discount rates ensure that investments made today are worth nothing in 10 years' time; the political cycle demands that no one looks beyond the next election.

The financial crisis is just one consequence of a system which demands that governments sacrifice long-term survival for short-term gains. In this case, political leaders on both sides of the Atlantic - from Reagan to Brown - decided to appease business lobbyists and boost short-term growth by allowing the banks to use new financial instruments, many of which were as dodgy as a three-pound coin. It made perfect political sense, as long as the inevitable crash took place after they left office.

For similar reasons we are likely to be ambushed by other nasty surprises: runaway climate change, resource depletion, foreign policy blowback, new surveillance and genetic technologies, skills shortages, demographic change, a declining tax base, private and public debt. Politics is the art of shifting trouble from the living to the unborn.

At first sight, the government's strengthening last week of the UK's climate change target seems like an exception to this political short-termism. In fact something rather interesting is taking place in Britain. While prime ministers in Italy and eastern Europe are demanding a bonfire of environmental measures in order to save the economy, in the UK politicians from all the major parties have made the connection between environmental destruction and economic meltdown. One of the fastest spreading memes is the proposal for a Green New Deal: a Keynesian package of environmental works designed to boost employment and channel public investment. If this idea is adopted, it won't be the first time that it has helped to rescue a major economy. The biggest and most successful component of Roosevelt's New Deal was the Civilian Conservation Corps, which employed three million people to plant trees and stop soil erosion.

But all such proposals soon collide with the realities of the political cycle. As Ed Miliband, the climate change secretary, admitted, "signing up to an 80% cut in 2050, when most of us will not be around, is the easy part; the hard part is meeting it, and meeting the milestones that will show we are on track." A recent paper in the journal Energy Policy shows that the government is pursuing the wrong policies to meet the wrong targets, produced by using the wrong methods to assess the wrong data. (Otherwise it's more or less on track.)

The paper shows that to help deliver even a small chance of preventing 2C of global warming, the UK can generate a maximum of between 17bn and 23bn tonnes of carbon dioxide between 2000 and 2050. In the first five years of this decade we produced 3.6bn tonnes: at this rate, our carbon budget would run out by 2028. To hit the government's temperature targets, the UK's carbon emissions need to fall by between 6% and 9% a year from 2012 onwards. At the moment, they're still rising.

Current policy, in other words, bears no relationship to the long-term target. On this trajectory, the only way in which the government could meet its obligations under the climate change bill would be to buy the cut from other countries, which means that it will make no contribution to a global reduction.

But at least in this case, there's a recognition that current policies have long-term implications. Elsewhere, the government simply refuses to look beyond the present, for fear of seeing something it doesn't like. For instance, it has failed to conduct any assessment of global oil supply. When I asked the business department what contingency plans it has to meet the eventuality that oil production might peak, it told me, "the government does not feel the need to hold contingency plans". The survival of our transport networks - and therefore of the economy - is secured by touching wood and crossing fingers.

In other cases, the question isn't even raised. Food policy everywhere is governed by the expectation that crop yields can keep growing to meet rising demand. A possible limiting factor is the supply of the phosphorus rock required to make fertiliser. I asked the researcher Tom Bailey to produce an assessment of global phosphate deposits that can be exploited at reasonable prices.

He found a wide range of estimates and a good deal of confusion between reserves (known deposits that can be readily exploited) and resources (the total geological stock). The most extensive survey published so far suggests that the global demand for phosphate is likely roughly to double by 2050. Can this demand be met without pricing food out of the mouths of the poor? Perhaps. Some reports suggest that phosphate constraints will provoke a global food crisis by the middle of the century.

This, in other words, is a critical question. Yesterday I searched the last five years of parliamentary records in the UK. It hasn't been discussed once. But the possibility that aircraft passengers and crew might be exposed to trace amounts of another phosphorus compound - tricresyl phosphate - has been mentioned 1,670 times in the same period. This is a minuscule issue in comparison with the question of whether the world can be fed. But it has the great political virtue of affecting people today.

In 1791 Thomas Paine complained that "the vanity and presumption of governing beyond the grave is the most ridiculous and insolent of all tyrannies". He was answering Edmund Burke's contention that a declaration made by parliament in 1688 bound the people of England "for ever". A parliament that considers only the immediate consequences of its decisions imposes the same insolent tyranny on succeeding generations. They have no means of contesting the legacy of economic crises, depleted resources and limited choices we bequeath to them.

What can be done about political short-termism? With the environmental thinker Matthew Prescott, I've hatched what might be a partial solution. We propose a new parliamentary body - the 100-year committee - whose purpose would be to assess the likely impacts of current policy in 10, 20, 50 and 100 years' time. Like any other select committee, it would gather evidence, publish reports and make recommendations to the government. It would differ only in that it had no interest in the current political cycle. Its maximum timeframe would be roughly the residence time of carbon dioxide in the atmosphere.

The members of this committee would not be equipped with crystal balls but they would be released from the need to balance the interests of the present against a heavily discounted future. Their purpose would be to provide a voice for those who have not yet been enfranchised. A 100-year committee could not insure us against political stupidity, but it would deprive governments of the excuse that they couldn't see trouble coming.

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