The human race is expected to swell from the current 6.5 billion to 9.1 billion people by 2050, with populations exploding in hungry developing countries and stagnating in rich nations, the United Nations predicted Thursday.

The increase of 2.6 billion people is equivalent to the combined populations of China and India today, according to the U.N. Population Division’s “2004 Revision” report. The growth is projected to be fastest in poor countries already struggling to feed their people.

But the overall trend shows a lower rate of growth than during the past 20 to 50 years, confirming previous estimates that the global population is rising but slowly stabilizing.

“The population continues to grow but at a lower pace, said Thomas Buettner, author of the report. “Family planning and lower fertility make the difference.”

In rich nations, declining birth rates means little or no population growth. An exception is the United States, which benefits from a relatively high number of immigrants, who have more children in the first generation.

Industrial countries as a whole are expected to see little change in their total population of 1.2 billion. In fact, a decline is forecast by 2050 in Germany, Italy, Japan, Russia and other states of the former Soviet Union.

“They have gone into territory that is unknown in human history,” Haina Zlotnik, director of the Population Division, told a news conference. “Mortality is low and fertility is extremely low.”

Populations in Europe would fall even further were it not for immigrants, estimated at 2.2 million each year, the report said.

In contrast, the population of poor nations is expected to climb from 5.3 billion today to 7.8 billion by 2050. Very rapid growth is forecast in the least-developed nations, where birth control is rare and five children per family is the norm.

INADEQUATE FOOD

Between 2005 and 2050, the population is projected to triple in Afghanistan, Burkina Faso, Burundi, Chad, Congo, the Democratic Republic of Congo, East Timor, Guinea-Bissau, Liberia, Mali, Niger and Uganda.

“They are the ones not being able to provide adequate shelter, adequate food for all their people,” Zlotnik said. “If fertility dropped downwards, they would be buying time to face the problems they are facing.”

In each of these countries surveys showed that women would like less children, if they had the choice, she said.

By 2050 India will have surpassed China in population and the two will account for about 50 percent of the world’s inhabitants. Women in India have an average of 3 children compared to 1.7 children in China, the report said.

The AIDS pandemic and other diseases like malaria and tuberculosis are slowing population increases in about 60 developing countries, the report said.

In southern Africa, especially in South Africa, where AIDS is prevalent, life expectancy has fallen from an average of 62 years in 1990-1995 to 48 years in 2000-2005.

U.N. forecasts say the average life span would fall to 43 years in the next decade before a slow recovery begins, because “in the long term we hope humanity is going to have success in combating this disease,” Zlotnik said.

AIDS and poor health care also means a fall in life expectancy in Eastern Europe, particularly in Russia and Ukraine.

Most of the world’s population lives in a very few countries. Four out of 10 people live in China or India and 8 of 10 inhabitants live in the United States, Indonesia, Brazil, Pakistan Russia, Bangladesh, Nigeria and Japan, the report said.