But less than a decade on, this confidence has all but disappeared, shattered by epoch-making events like 9/11 and the onset of climate change.

There are even now fears that we may even be entering an age of scarcity – in food, water and energy.

All this at a time when we're facing a credit crisis of which Mervyn King, governor of the Bank of England and not a man prone to exaggeration, said: "Not since the beginning of the First World War has our banking system been so close to collapse." So much for a new gilded age.

It's against this backdrop of doom and gloom that Oxfam's head of research, Duncan Green, has been on a whistle-stop tour, including visits to Leeds and Bradford, to talk to audiences about poverty and power. They're the themes of his new book, an accumulation of more than 20 years' research into ways of reducing poverty. Green has been involved with non-governmental organisations (NGOs) all his working life and has spent time in many of the countries caught on the frontline of the battle against destitution and, more latterly, climate change.

One of the main problems, he says, is that despite improvements during the last century millions of people remain trapped by poverty. He points out that while the average annual GDP per capita is about $10,000 (£6,400), one in four people in the world earn less than $500 (or £320) a year.

His solution, and he concedes that some people won't like it, is a "redistribution" of power and opportunities. "It's not a popular word and it won't be plain sailing, but such changes have taken place historically when groups in society have combined with effective states and committed political leaders. That's what galvanises countries."

He argues that just because a nation is impoverished doesn't mean it always will be. He uses Botswana as an example, pointing out that since gaining independence in 1966 it has, through smart economic management, become an African success story.

"There are still problems in the country, but it is now richer than South Africa." South Korea, he says, has also undergone a dramatic economic transformation. "Half a century ago it was poorer than Sudan, but it's now 12 times richer."

However, Green warns that climate change could halt such progress in the future, and he has little time for global warming sceptics. "Just because it's fashionable doesn't mean it's wrong," he says.

Annual carbon emission levels are estimated to be about 20 tonnes per person in the United States, and three tonnes in China. But Green believes we need to get down to an average of about one tonne per person per year, if we are going to stave off the ravages of climate change. And to do so, he says, will require huge technological improvements.

"The only historical precedent is the kind of mass industrial shift to arms production that takes place during wartime. The challenge is for us to do it through choice rather than in response to actual climate chaos, because by the time climate disasters really start hitting the US and Europe, it may be too late for many of the poorest parts of the world."

Most scientists believe we are heading into uncharted territory over global warming and Green agrees. "If we carry on like this we know the ice caps will melt and sea-levels will rise and it's the people at the sharp end who are most vulnerable. We have farmers in Uganda saying all their inherited knowledge of the land is worthless because they no longer know when it will be dry because the climate is so erratic."

The situation is not helped by the global financial crisis and there are concerns among humanitarian agencies that this will be used by governments as an excuse to reduce foreign aid. Which is why Green is calling for the kind of radical approach that President Franklin Roosevelt adopted to revive the crippled US economy following the Great Depression.

"We need a global version of the New Deal, but we cannot afford to wait for the shocks of war and catastrophe that delivered that change."

Despite the magnitude of the challenges that lie ahead, he believes there is some cause for optimism. "There is better primary education, poor people now have access to banks and women's rights are much more widely respected," he says.

"If you stood here today in 1800 people would have argued it was economic madness to get rid of slavery, but 30 years later it was abolished. And if you stood here in 1900 there was only one country in the world where poor people and women were allowed to vote, and that was New Zealand. So when I look at things in an historical context it makes me optimistic about the future.

"If it wasn't for climate change I would be a lot more optimistic, but if the science is even half right we're facing our greatest challenge and we have no choice but to fight it, otherwise we are condemning one-and-a-half billion people to eternal poverty."

Green has dedicated much of his time to understanding how poverty can be reduced, but as an Oxford University graduate with a first class physics degree, he could easily have gone down a different path. It was only after living in Argentina during the military dictatorship of the early '80s and then travelling and working in El Salvador and Nicaragua, that he became aware of the importance of social movements in creating change.

Improving the lives of the poor remains his guiding principle. "It would cost three billion dollars a year to tackle global poverty, which is one tenth of the cost of the Iraq war. The money is there; now it's about the political will."

That's all well and good, but we've been here before. The Make Poverty History campaign in 2005 was supposed to help those African countries shackled by debt, but three years on the European leaders who attended the G8 summit at Gleneagles have failed to deliver on their promises.

Green admits that this is frustrating but he disagrees that organisations like Oxfam are simply banging their head against a brick wall.

"There is a lot of talk and hot air for a little bit of change, but it's like John Maynard Keynes said, politicians 'who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist,' and I believe we can make a difference."

From Poverty to Power – How Active Citizens and Effective States Can Change the World by Duncan Green is published by Oxfam, £15.95.