“After years of strong growth, many Brazilians grew optimistic, but for many people who improved their lot, there is now a sense that their potential to rise further is limited,” said Samuel Pessoa, a researcher with the Brazilian Institute of Economics at the Fundação Getúlio Vargas, an elite university in Rio de Janeiro. “People are worried.”

There is little prospect that the BRIC economies will ever return to the roaring growth that had come to seem normal.

“Many superficial observers just assumed that the BRIC countries would keep growing at the rate they did in the first decade, which was very unlikely,” said Mr. O’Neill, who recently retired from Goldman.

Mr. O’Neill said that as China moved to a more consumer-based economy, “the winners and losers of the new China are probably going to be quite different than the winners and losers of the old China.”

Even the most optimistic forecasts do not see the United States or Europe reaching the double-digit levels of growth that China and India have enjoyed over the last decade. Analysts are expecting that growth in the United States will rise from less than 2 percent this year to nearly 3 percent next year. Because the developed economies still account for nearly 60 percent of the global economy, even a slower pace of growth can provide more economic activity than faster growth in the developing world. There are fears that even the lackluster recovery in United States, Japan and Europe could be derailed if China’s problems grow significantly worse. Some economists in China are warning that Communist Party leaders may not be able to smoothly wean the country off years of government-fueled development.

For emerging economies, analysts say that the current cooling of growth is taking some of the countries to a more sustainable pace of expansion after years of acceleration that some considered unhealthy. In China, the 14.2 percent expansion seen before the peak in 2007 is not likely to be reached again, though the expected growth of 7.5 percent next year is still impressive.

“Even though it’s slowed down some, there is still a big opportunity,” said Barry P. Bosworth, a China expert at the Brookings Institution.