It may seem ineffective, but we need G8 in order to face the daunting future

The G8 summit, which opens today on Hokkaido, in Japan, conjures images of a political A&E ward on a Saturday night. President Bush, leader of the greatest nation on earth, is discredited and almost time-expired. Gordon Brown leads a government most of whose own members want him to disappear into a hole.

Silvio Berlusconi presides over a gangster culture that renders it impossible for Italy to present a serious face to the world. Nicolas Sarkozy should enjoy the prestige of a French president secure in office until 2012, but he has grievously injured his own power base by his first-year antics. Russia's new president, Dmitry Medvedev, may well add up to nothing, in the absence of Vladimir Putin to tell him what to think.

All this matters, when the G8 is called upon to address the gravest issues of modern times. In some years, in advance of these gatherings, national sherpas are obliged to scrabble around exchanging emails, to identify a plausible agenda for their bosses. On Hokkaido, by contrast, they are debating shocking evidence on climate change, together with economic slowdown in the wake of soaring food and energy prices and world poverty.

These are daunting challenges, which most of the assembled leaders are ill-positioned to address. At G8s, unlike other international forums where big bureaucracies represent national interests, personalities matter. To get results the Japanese, as hosts, must exercise impressive powers of leadership. Instead, there are already signs that they will pursue their usual search for consensus, which means the triumph of a lowest common denominator.

G8 meetings can no longer carry conviction until China and India are granted full membership. There are also arguments for admitting representatives of other important global interests, for instance Brazil, South Africa, maybe an Islamic nation. The difficulty is that, if the group expands significantly, it will forfeit the intimacy which is hailed as its most important virtue. Chinese leaders are always uncomfortable in informal discussion, preferring to address carefully prepared scripts. Cynics observe that most of the communique for the Hokkaido meeting has already been drafted. The view of G8s as mere theatrical performances is liable to gain ground if the group expands.

Yet, whatever their limitations, it seems sorely mistaken to dismiss these summits as wastes of time and money. Globalisation both of problems and commerce is the dominant force of our times. It must therefore be useful, indeed indispensable, for national leaders to make human contact with each other. Bilateral conversations, even hampered by the necessity for interpreters, possess significant value.

The most notorious G8 of recent times was that held at Gleneagles in 2005. Not only was the occasion overshadowed for the hosts by the horror of the London bombings, but extravagant promises were made to attack world poverty. These won acclaim for Tony Blair, who was perceived as having responded to the appeals of Sir Bob Geldof with energy and success.

Unfortunately, of course, much of the pledged cash has never been delivered. It was the G8's Alberto Vilar moment. Vilar, you may remember, was a tycoon who promised huge sums to good causes, including the Royal Opera House, but who failed in the end to make good on those pledges.

Last weekend I put the Vilar point to a Gleneagles veteran, a diplomat. He responded that he thought cynicism misplaced, about both G8s in general and the Scottish one in particular. It was an important achievement to set targets, he said, even if they are still unmet. As a result of the 2005 agreement, more money for poor countries has been forthcoming. A fortnight ago, the Japanese significantly increased their international aid commitment. They were moved to act explicitly because, as Hokkaido hosts, they needed to be seen to display generosity.

Unfortunately for the developing world, and for Africa in particular, most G8 members this week will be more interested in the plight of their own societies than of anybody else's. Lip service will be paid to good causes. But the overwhelming preoccupation of leaders will be the impact of rising food and energy costs upon the world's biggest economies.

Tensions will soon become apparent, between the perils posed by climate change and the clamour for relief from threatened living standards. Democracies being what they are, the latter force is likely to gain priority. The power of green lobbies will diminish in the lean years ahead, just as in supermarkets cheap food is likely to gain ground against expensive organic products.

Any political party in the west that wants to get itself elected will have to offer an electorate prospects of secure energy sources and stable food prices, even if both carry additional environmental risks and costs. We are likely to hear much more about both nuclear power and GM crops. Most of the G8 leaders know this. The more extravagant the green rhetoric that emerges, the less likelihood there is that its authors will mean what they say. Idealism shrinks in times of economic stress.

No doubt the summit will spare some unkind private words for Robert Mugabe, especially as South Africa's president Thabo Mbeki is calling in on Hokkaido. But in the case of Zimbabwe, also, breadbasket issues at home make national leaders less interested in addressing moral ones abroad.

The American guru Richard Haass wrote recently in Foreign Affairs journal that rather than a multi-polar world, we are moving into a non-polar one. It is becoming progressively difficult to mobilise an international quorum in support of any objective, however worthy and important. This reflects not only the US's loss of moral authority, but also a dilution of power in consequence of globalism, which makes it ever harder for any nation to forge a consensus in support of decisive action.

This works to the advantage of tyrants and mischief-makers. The EU, for instance, should be presenting a united front to prevent the Russians from using their newfound energy clout to blackmail individual nations. Instead, much to the delight of the Kremlin, each EU member state is scrabbling to extract the best bilateral deal it can get from Moscow. The UN security council shows itself increasingly weak and more anachronistic. Nato is atrophying. The IMF and World Bank face growing sceptical scrutiny.

Capitalist societies found life much less complicated in the cold war era, when it was perceived as essential to follow strong US leadership amid the threat from the Soviet Union. Those days have gone. If the world's major powers are henceforward to get anything done, it must be through the concerted efforts of members of such bodies as the G8. Today, unfortunately, most still prefer to hang separately than together. Our global predicament may have to get a good deal worse before they acknowledge that common action against shared perils must transcend the familiar, disastrously outdated pursuit of national interests.

Max Hastings