The joke in Sao Paulo used to be that Brazil was the country of the future, and always would be. But by the look of the past few years, that barb may have lost its sting. Over the past decade, the big economies among the emerging markets – particularly the Bric countries of Brazil, Russia, India and China – have shown they are capable of providing more than an entertaining sideshow to the main act of the US, Europe and Japan.

Having already taken a rising share of global economic growth and trade, those four emerging markets pressed home their advantage during the global financial crisis. Their economies, whose financial systems proved largely immune to contagion from the virulent disease that spread around capital markets, continued to hold up relatively well while the US and Europe went into a tailspin.

Russia, whose economy remains heavily dependent on oil and gas exports and hence on global energy prices, was a glaring exception. Many analysts regard Russia as a semi-detached member of the grouping, and think that the Bric acronym should read Bic.

Ricardo Melendez Ortiz, executive director of the International Centre for Trade and Sustainable Development, a Geneva-based thinktank, says: “2009 was the year the power shift materialised in favour of the Bics.” He points at the huge contribution they made to global growth, about half of it according to some estimates, and to the rapid expansion of trade between the Bic economies. China overtook the US as the main trading partner for several countries in Latin America.

But others caution about simply projecting forward current developments. Although they are likely to continue to gain in prominence, not least because of the sheer size of their populations, it may be premature to assume the big emerging economies will inevitably take over the baton of global growth and global economic governance from the US and Europe. The growth model remains heavily dependent on export demand, as it always has. And moves towards co-ordination of policy remain more show than substance.

Charles Dumas, chairman of the London-based consultancy Lombard Street Research, says capital flowing into emerging markets is more to do with investors escaping dismal returns in the rich economies than any well-founded confidence about growth. In particular, China – which is by far the biggest of the emerging market economies, and sets the tone for much of emerging Asia – has relied for years on its companies pumping out exports to the US and Europe to fill their order books.

Now, the world is in dire need of consumer demand: US households, having dragged the global economy along throughout most of the past decade, are finally increasing their saving to repair battered balance sheets. But there appears little likelihood that the emerging markets in general and China in particular are likely to fill the gap.

Although China did more than most to pump demand into the economy during the financial crisis, unveiling a $585bn stimulus package at the end of 2008, it was directed in ways likely to exacerbate rather than relieve those imbalances. Focused largely on fixed investment, the stimulus package will in the medium-term create yet more industrial capacity in China's economy, and unleash yet more floods of cheap exports on to the world market.

The risk is that there is not enough demand to buy them, and they end up in destructive competition with exporters from elsewhere. Meanwhile China's consumers are held back by an undervalued exchange rate, which makes imports expensive, and a financial system that directs savings to companies rather than households.

“If they curb domestic demand that means we're right back to where we started from, which is export-led growth with a dose of inflation,” Mr Dumas says.

“It's the Chinese gaining world share by mauling the exporters of Japan and Germany.”

The concerns about China's growth model extend to the inside of the emerging-market camp as well. Brazil's manufacturers have been complaining bitterly that, with the Brazilian real pushed up by the soaring prices of Brazil's commodity exports, Chinese manufactures have been driving them out of their home market, let alone third markets abroad.

And it is such tensions that undermine the notion of a unified camp of Bric countries, or a wider grouping of emerging markets. Given the population size of some of the big emerging market countries, and how much they have to catch up with the rich world, it is not surprising their contribution to the world economy is growing.

But to talk of the rising powers forming a coherent bloc of economic power than can run the world is, at best, premature.