Brazil, Russia, India and China, the so-called Brics, are predicted to emerge as major world players by 2050. In this, the last in a four-part World Service series called Brics: The Changing Face of Global Power, the BBC's Peter Day examines why the so-called Brics nations may not meet expectations.
The contention that Brazil, Russia, India and China will all be top global powers by 2050 is a powerful one.
The decline in India's water tables is an indication of future problems
But things could go wrong to postpone or cancel this date with destiny for one or more of the Brics.
Russians, for example, are dying younger and breeding less. Russia is shrinking, and that is no way to build a new country.
Russia's Security Council fears that by 2050, the population will have shrunk by one third, from 145 million at present to about 100 million.
In the packed cafes of post-Communist Moscow, the future has already arrived in an optimistic, materialistic rush. For the customers awash with international brand names, the Brics predictions of a rich and powerful Russia ring very true indeed.
But beneath the glitter of Moscow - infested with Rolls Royces, people tell me - is some deeply Russian gloom about a country fallen into the hands of a preposterously powerful few.
These are the so-called oligarchs who have grabbed so much of the natural resources which create the riches that put Russia up with the other Brics nations.
Grigory Yavlinsky, now head of the liberal Yabloko Party, is one of the reformers who tried to ease the Soviet Union's transition from communism to capitalism. He believes Russia must answer some important questions before it becomes an economic superpower.
"As for today, oligarchic structure is making obstacles for Russia because an over-monopolised economy mainly based on raw materials is not what Russia needed from the point of view of future development," he says.
"I want to say even more: The strategy of oligarchs in Russia is different from, say, robber barons in America in the beginning of the 20th Century and the end of the 19th Century.
"They were robbing America and investing in America. Russian oligarchs are robbing Russia and investing in Cyprus or Switzerland or I don't know where."
Half a world away from Moscow, in Brazil, Diogo Mainardi - writer of a controversial magazine column - is sceptical of government pledges to help the 50 million Brazilians who live in miserable rural poverty or drug-ridden urban slums: he says the answer to Brazil's problems is not big government.
"Brazil stays behind - much behind," he said.
"We are still far away. We are a banana republic and we have to chew this country for many decades before we become really a power."
Mr Mainardi argues that Brazil's industry is very much "directed, subsidised and it doesn't help in the long run."
"The charity of the state: that's the only answer we've imagined in the last 60, 70 years, and it doesn't work. So if we had some savage capitalism, like China, it could work better than the way it is."
So are we left with the "ICs"? What you actually have, when you look at the Brics thesis, is two great producing countries and two great raw material countries supplying the producing countries - that's what it's actually about.
But then, the people at the Brazilian Institute of Social and Economic Analysis - who mistrust market forces - believe China is not sustainable anyway.
Some doubt whether Brazil can sustain its growth
"I've been there, it's not a sustainable society - socially and technologically," says director Candido Grzybowski.
"India also has a lot of problems. Russia was a power in the past; I don't know if it will be a new power.
"If you look to our exports, it's mainly nature we are exporting. We are exporting our future instead of building our future, and this is not sustainable."
With all this scepticism in the air, it's time to go back to the fountainhead of the big Brics idea at the Goldman Sachs offices in London.
Economist Jim O'Neill, the man behind the Brics proposition, admits Brazil has suffered from bad economic policy - but does not share this scepticism.
"In Brazil, people jokingly say, well, you only put the B in there because it makes the word sound good," he said.
"In Brazil's case, they've got the population, they've got some of the infrastructure, they've got enormous resources - and I think that the doubting Thomases about Brazil may be in for a pleasant surprise."
Similarly, he adds that the last time he was in Russia, he sensed that the country's policy-makers "know what's needed to be done."
'Chaos in the countryside'
But nature still has the ability to derail fragile human plans.
An even wealthier world is bound to increase pressures on the environment.
The influential American environmental campaigner, Lester Brown, founder of the Worldwatch Institute and the Earth Policy Institute in Washington DC, says that growth in at least three of the four Brics countries could be overwhelmed by an environmental crisis.
"One of the big challenges that China faces is the tightening water supply in the northern half of the country," he explained.
"This will obviously affect agriculture - but the water supplies could become so tight that they will affect industry as well.
"With Brazil, it's the deforestation of the Amazon basin that could be a suicidal sort of move, if it affects the recycling of rainfall to the interior and the south of Brazil.
"India's problem is also a water problem: water tables in India are now falling in most states. And when those aquifers are depleted - as they will be - as one Indian water expert said: 'There could be chaos in the countryside.'"