The Issues: Arnie has taken on Bush. Now it's your turn, Tony

Writing exclusively for The Independent on Sunday, the Republican Governor of the largest US state gives robust support to Tony Blair - and contradicts his President - by saying that "we have no choice but to take action" to reduce the pollution that causes climate change. In a direct challenge to the leader of his party he writes: "The debate is over. We know the science. We see the threat posed by changes in our climate. And we know the time for action is now."

He calls on "governments everywhere" to combat global warming and - again in sharp contrast to the President's position - says that this will boost rather than damage the economy.

His intervention will have an effect on the preparations for the summit, which opens on Wednesday, by demonstrating the President's growing isolation on the issue at home. London has been the scene of two days of intense talks, chaired by Sir Michael Jay, the Permanent Secretary at the Foreign Office.

The location of the talks, at Lancaster House in London, was kept secret in order not to attract demonstrators. They dragged on into the early afternoon until, with the sound of Bono ringing in their ears from Hyde Park nearby, the negotiators finally agreed a form of words which will now go back to the respective capitals for confirmation.

There had been a real danger that the talks would collapse after the French negotiator, Maurice Gourdault-Montagne had staked out President Jacques Chirac's demands, which went well beyond anything the Americans were likely to accept.

President Chirac was insisting that the Gleneagles communiqué should specifically mention the Kyoto Protocol, and that it should recognise the scientific evidence of global warming and the need for "urgent" collective action, and looks towards a new "legally binding" agreement when it expires in 2012.

After the US and French negotiators had met privately, they were able to settle for a provisional agreement which praises the Kyoto Protocol as an effective means of combating global warming, without committing the US to signing it. The document also recognises the need for collective action.

Governor Schwarzenegger's article crowns a series of setbacks at home for President Bush over his hardline stance on global warming. Ten days ago, in a vital shift, the US Senate resisted intense pressure from the White House and voted 53-44 to recognise that global warming was taking place, and that pollution was largely responsible. Senators then called for "a comprehensive and effective national program" of action.

Other senior Republican governors, including Mitt Romney of Massachusetts and George Pataki of New York, have announced programmes to cut pollution, as have the mayors of more than 130 towns and cities across the country. Even the religious right is putting pressure on the President.

Governor Schwarzenegger avoids explicitly criticising President Bush, or mentioning him by name, but his call for action could scarcely be more strongly stated. In a thinly veiled attack on the President's insistence that tackling global warming would damage the US economy, he writes: "Many people have falsely assumed that you have to choose between protecting the environment and protecting the economy. Nothing could be further from the truth. These steps are great for the environment, but great for our economy too."

Under Governor Schwarz-enegger, California is aiming to cut its emissions of the pollution that causes global warming by 80 per cent by 2050 - the toughest target set anywhere in the world. Measures are being taken to introduce cleaner cars and accelerate the expansion of renewable sources of energy.

Ministers were deeply worried by President Chirac's likely impact on the summit, which he joins after the announcement in Singapore on Wednesday of the location of the 2012 Olympics. They suggested that if Paris were chosen he would be co-operative, but if London won he would be determined to make life difficult for Mr Blair.

In the event, the French, who had drawn up a list of six prerequisites for signing any Gleneagles communiqué, claimed yesterday that they had done Britain a favour by setting out such explicit demands. As British officials privately acknowledged, there is no real disagreement among any of the EU governments about the need to combat climate change. The tension was between Tony Blair, who was anxious to reach an agreement acceptable to George Bush, and Jacques Chirac, who appeared to be aiming for an open rift that would have led to six or seven of the G8 leaders signing a communiqué without US support.

It was not clear yesterday whether the so-called "ad-ref" agreement reached by the negotiators fulfilled the French demand for "recognition of the irrefutable scientific proof of the reality of climate change and that it is in large part of human origin" and "recognition of the necessity of urgent action, taking account of the dangerous and potentially irreversible character of the evolution of climate change". But one French source said it contained "a form of words which basically amounts to a recognition of the problem".

He added: "There will be references to the fact that the Kyoto scheme is the best way to stem climate change, and there will be a recognition of the need for collective action."

Until the G8 leaders sit down to talk, most of the hard political work falls to the so-called "sherpas", the professional negotiators whose job is to thrash out a provisional agreement before the leaders meet. The British negotiators were desperate to meet French demands in a way that did not require President Bush to eat his own words in public. They have found it easier to agree on specific measures that can be taken to introduce low-carbon technology, and to involve China and India, which both have vast coal reserves and huge unmet energy needs.

The negotiators had some light relief late on Friday night, after hours of exhausting talks, when they called in to see Mr Blair in 10 Downing Street, and discovered that Bono, the former lead singer of U2, had arrived ahead of them. The meeting was "brief" but "very pleasant".

Ministers are confident that the US government will eventually have to accept the scientific evidence. The former environment secretary Stephen Byers, who was asked by Mr Blair to co-chair the International Climate Change Task Force, has said: "There is increasing recognition among politicians, business and the public in the US that climate change needs to be tackled urgently. George Bush is in real danger of becoming isolated not just from the international community but from within his own country."

With so much official attention on global warming, there were fears among the aid agencies that, despite the vast publicity surrounding Live8, Africa could be shortchanged at the Gleneagles summit.

With agreements on 100 per cent debt relief for 38 impoverished countries and a doubling of the EU overseas aid budget already secured beforehand, enough had been done for the politicians to feel confident of the success of this part of the G8 agenda. Gordon Brown, the main architect of the deal, said yesterday at a meeting in Edinburgh, organised by Christian Aid: "We are seeing Britain at its best, united as one for a great cause. This is more than a week's work at the G8. It is a lifetime's work across the world."

Others were more cautious. Oxfam has been alarmed by reports that the huge increase in aid will take years to deliver. Africa has been promised an extra $50bn (£30bn), but leaked documents have suggested that the money might not be paid until 2010. "The last thing Africa needs is a fudge," said Jo Leadbeater, Oxfam's head of EU advocacy. "Delaying the $50bn increase will be responding to today's target five years too late. Every cent is money that could have saved the lives of the world's poorest people ... 2010 will be five years too late for the 55 million children who will die waiting for the world's richest leaders to deliver on their promises."

Alongside the private talks on climate change, negotiators are trying frantically to reach a clear commitment on how much extra aid to offer, and on conditions to ensure that the money is not embezzled by corrupt officials.

One reason for the urgency is that next year, G8 will be chaired for the first time by Russia and will hold its annual summit in St Petersburg. Russia's President Vladimir Putin has been lukewarm about the response to the crisis in Africa. When Mr Blair visited him in Moscow last month, he emphasised the importance of not allowing aid to prop up corrupt regimes. Tackled about corruption in his own country, with Mr Blair sitting next to him, the Russian President retorted, to the alarm of many: "We all know that African countries used to have a tradition of eating their own adversaries. We don't have such a tradition and I believe the comparison between Africa and Russia is not quite just."

To add to the international pressure on him, the Prime Minister will be given a public warning today to abandon any ambitions he has to "winch Germany away from France" on the issue of farm subsidies. As well as being G8 president, Mr Blair assumed the six-month presidency of the EU on Friday.

He wants to use his period in office to drive through reform of the Common Agricultural Policy, which currently hinders developing nations from selling their produce to Europe.

British officials had rested some of their hopes on the Germany opposition leader, Angela Merkel, who is expected to replace Chancellor Schröder later this year. But the German ambassador to the UK, Thomas Matussek, has warned in an interview on today's GMTV on Sunday that a Merkel administration will preserve the German-French axis, and that cutting EU subsidies to French farmers would "violate the spirit of solidarity from which Britain profited very well when you were not in the fantastic shape you are in now".

Enjoying Gleneagles: Fairtrade coffee in the rooms - but put the haggis on hold

By Francis Elliott and Severin Carrell

George Bush has been "briefed on haggis" - and has no intention of going near the stuff.

But other culinary oddities not often seen in Texas await him in his four-room £1,600-a-night presidential suite in Gleneagles this week.

Each of the hotel's 269 rooms is stocked with Fairtrade tea, coffee chocolate and sugar as Downing Street loses no opportunity to ram its message home.

Mindful, no doubt, of the likely reaction to world leaders taking in a round of golf in the midst of debt relief negotiations, each of the hotel's three championship courses has been closed.

President Bush has said that, instead, he and Laura may take a stroll "in the Scottish mist" through the hotel's grounds, its landscaped gardens inspired by Lancelot "Capability" Brown.

That is if the First Lady has any time out from the busy "spouses' programme" being led by Cherie Blair. A trip to Glamis castle, the late Queen Mother's girlhood home near Dundee, is reported to be on a busy agenda.

Here, too, the dread hand of the No 10 media management team has been felt. Delegates' convoys will be powered by "biofuel", a mixture of 95 per cent petrol and 5 per cent cellulose derived from straw.

Mrs Blair, who will arrive at Gleneagles hotfoot from pushing London's Olympic bid in Singapore, may have a tricky diplomatic job facing Bernadette Chirac, Lyudmila Putin and Mrs Bush in the event of a London victory in Singapore over Paris, Moscow and New York.