How many world leaders does it take to defuse a ticking time bomb? As G8 countries wrangle over climate change, I can’t help thinking that the bigger the crowd, the more likely it is that everyone will wait for someone else to go first. If you do that with a bomb, of course, you are taking a far, far greater risk than if you tried to tackle it. “You take it.” “No please, after you” is a recipe for disaster.

Two new American studies suggest that the tipping point for irreversible global warming may have moved a step closer. Carbon dioxide emissions have been increasing at about 3 per cent a year since 2000, according to the US National Academy of Sciences. That is three times as fast as in the 1990s and outside even the worst scenario modelled by the Intergovernmental Panel on Climate Change (IPCC). Meanwhile, satellite pictures seem to show that Arctic ice is shrinking more quickly than the IPCC had predicted. Maybe those who routinely call the IPCC “alarmist” will think again.

The wrangling in Germany is depressing. While Tony Blair and Angela Merkel stick doggedly to their proposal that EU members should set binding targets to cut their carbon emissions by 50 per cent by 2050 from 1990 levels, George Bush has shambled up with an offer to host a parallel set of meetings aimed only at securing voluntary targets.

Déjà vu? Not quite. This is the first time that the White House has said that it wants to be part of an international agreement when the Kyoto treaty expires in 2012. It is the first time that it has backed a long-term goal. Yesterday Mr Bush also indicated, to general relief, that his talks would “fold in” to UN efforts not create a rival initiative. Professor Rob Stavins, climate change economist at Harvard, puts it to me like this: “Bush has only just sat down (finally) at the table. So don’t immediately start to shout: ‘Why aren’t you eating yet?’.”

It’s Grrrrr8 (honest)

As the G8 summit begins in Germany, Hugo Rifkind explains everything you need to know – and lots of stuff you don’t

Multimedia

• Video: Our young man in Heiligendamm

• Audio: Behind the scenes at the G8

• Pictures: G8 summit

BACKGROUND

• Quotes: what Putin told The Times

• Blair reinvented the Middle Ages

• The West is starting this Cold War

• Save the planet: give to China

Related Internet Links

• Official site of the G8 summit Heiligendamm

The world needs America to help to solve climate change. But in her absence, Europe has created a powerful momentum. The Kyoto Protocol has had only a negligible effect on carbon emissions. But its existence has prompted a dozen US states to set their own emissions targets. Companies such as General Electric, sensing an opportunity to clean up in both senses of the word, are calling for carbon taxes. There are five climate Bills pending in Congress. The EU’s Emissions Trading Scheme has created the world’s first carbon market, putting a value on pollution. While the carbon price has been laughably low in the first 18 months, because governments were too generous to polluters, a tighter regime will begin next year.

When I asked Americans why the Bush Administration is so wary of carbon trading, the least bureaucratic and most free-market mechanism available, one said: “Not invented here.” Yet “cap and trade” is an American idea. It was first used in the US in the 1990s to cut sulphur dioxide that was causing acid rain. So an American idea has created a whole new business. American studies say that climate change is accelerating. And the greatest investment in clean technologies is coming from America. Why is the President still moving crabwise?

Partly because of a perfectly valid question that America has been asking ever since it backed out of Kyoto in 1997: will the West foot the bill for solving a problem to which newly industrialising nations are increasingly contributing? And what will that do to our competitiveness?

As the world’s richest country, the US fears being landed with a monumental bill. It is wary of conceding anything without China and India at the table too. And those countries have always been able to use US non-compliance as an excuse for their own. If America enters negotiations, there are a host of ideas for gradually drawing in the other big emitters. But the West is going to have to pay in the short term, while these countries industrialise.

On Tuesday the Indian Prime Minister said that he had no intention of constraining Indian growth, given that the West had created the global warming problem. And the moral argument is clear: the average American still has a carbon footprint roughly eight times that of a Chinese citizen, and 18 times that of an Indian. China now has a climate plan that is less vague than America’s, including stringent energy efficiency goals. And it already generates twice as much electricity from renewable sources as we do in Britain. We cannot pretend any kind of moral equivalence until we have put our own houses in order.

About $5 billion went from West to East last year to provide cleaner technology. The UN’s Clean Development Mechanism (CDM) lets EU companies earn carbon credits by paying to clean up Chinese factories, for example. China is laughing all the way to the bank: Beijing has already started to tax CDM profits, which should make Western governments wince. Yet it still makes sense to take a ton of carbon out of the atmosphere where it is cheapest for us to do so. In fact, we should be spending far more money in China, if we want to lure it on to a lower-carbon path before it invests in any more dirty power stations.

This kind of subsidy may sound like economic suicide. But if you look at it as aid, perhaps not. Some money may go astray. We could end up paying Brazil not to cut down trees, and wake up to find the Amazon has shrunk. But we may have to accept some waste as inevitable.

For every clean Chinese factory there will be a Western company manufacturing the solution. Businesses are already scrambling for pole position in the low-carbon economy. And the ultimate payoff is energy security and a stable climate: the benefits will flow West as well as East.

So how many world leaders does it take? Fifteen countries produce about 85 per cent of the world’s emissions. Their leaders, at least, fit round a table.

Times Recommends

• Care in old age: we won’t pay, the State can’t
• Viewers’ choice: our talentless Everyman
• Memo to the poor: go forth and don’t multiply