By Steve Schifferes
BBC News economics reporter at the G8 summit in Gleneagles
The US wants investment in cleaner technologies
Was the summit a success? It depends on the standards you use to measure it.
Certainly by the standards of previous G8 summits this one has achieved a great deal, despite the disruption caused by the bombings in London.
It is unprecedented to reach substantive deals - such as the $50bn (£28.8bn) Africa aid boost and debt-cancellation deal - at such meetings.
The G8 summit also agreed to renew efforts to forge a trade deal, pledged $3bn for the Palestinian authority, and said it would increase access to Aids treatment.
The summit broke new ground by bringing poverty campaigners and leaders from developing countries face to face with the world's eight most powerful leaders.
In the words of Tony Blair: "It isn't the end of poverty in Africa, but it is the hope that it can be ended. It isn't all everyone wanted but it is progress - real and achievable progress."
And Bob Geldof, the former rock star and Live 8 organiser, paraphrased words first uttered by Winston Churchill.
"I wouldn't say this is the end of extreme poverty, but it is the beginning of the end," he said.
Of course, the various deals fall far short of what many campaigners wanted.
But they have set an important precedent which could lead to further developments over the course of the year, when other key negotiating meetings are taking place.
"This is the single most successful summit in the 30-year history of this event," Professor John Kirton, director of the University of Toronto G8 research group, told the BBC News website.
Wind farms could provide part of a cleaner solution
Movement may seem glacially slow to campaigners. But from a longer-term perspective the aid deal and the statement on climate change could represent a historic turning point.
Firstly, the aid deal represents a reversal of the pattern of the last 20 years, where aid flows to developing countries have fallen amid concerns that the aid is being wasted through corruption.
Still to be resolved is how the aid can be made more effective this time. This is a goal shared by both campaigners and Western governments, but with some differences on the means that should be used.
Secondly, the language on climate change represents a gradual movement by the US towards the recognition that global warming is a reality, and caused by human activity.
Although President Bush has said so before, to sign up with other global leaders to such language is an important first step towards bringing the US into the post-Kyoto process.
It was also unlikely that the current US government would reverse its long-standing opposition to emission targets, but the combination of domestic and international pressure could well lead a future US administration to sign up to the next climate change convention.
Involving campaigners and developing nations in G8 was a first
The G8 was historic for involving other sectors in the negotiations for the first time.
It was the first summit at which civil society, in the form of non-governmental organisations (NGOs), played a central role.
This was a choice made by the UK government, who were encouraged to involve them by the mass mobilisation of the Make Poverty History campaign and Live 8 concerts.
"A key part of the summit has been the unprecedented opportunity it offered for civil society to take part in the central deliberations, said Professor Kirton.
He added "the so-called 'sherpas' who plan the summit met civil society representatives in advance of the meeting, (and) the NGOs were offered space in the media centre.
"The Make Poverty History and Live 8 campaigns played the most important role so far of any G8 summit in showing how civil society can exert real pressure and influence the agenda and outcome," Professor Kirton said.
Will non-African nations ever get a similar level of aid?
But it will now be hard for other G8 summits to exclude these groups in the way they were completely excluded from the Sea Island Summit hosted by George Bush in 2004, for example.
Moreover, this G8 summit continued and strengthened the trend to involve developing nations in the negotiation process.
The leaders of seven African nations attended the summit, as did the leaders of the five leading "emerging market" countries: China, India, Brazil, Mexico, and South Africa.
It will be hard not to invite them in the future, as they are playing an increasingly important role in the world economy and trade negotiations.
Battles to come
Blair and Bush are both troubled by global terrorism
Of course the G8 summit did not solve all the world's problems. But there are three key meetings later this year where campaigners and others will be able to test the G8's real resolve.
In September, the UN meets in a special session in New York to consider reform and progress towards reaching the millennium development goals.
Will the major powers pledge the same increase in aid ($25bn) for non-African countries that is required to lift their poor out of poverty by 2015?
In December, the trade issues will be confronted head-on, as the world trade talks resume in Hong Kong in a last-ditch effort to reach a deal after four years of wrangling.
Will rich nations be prepared to eliminate their agricultural subsidies in order to open their markets to the poor countries? And how much will they try to force the poor countries to open their markets first?
Also in December, the contracting parties to the UN framework convention on climate change will meet in Montreal to discuss what should happen when the Kyoto protocol runs out in 2012.
Will they be able to agree a new regime to regulate global emissions that will include both developing countries and the US?
None of these issues is easy to resolve. But the political will shown at the G8 does at least give some of these negotiations a fighting chance.