The world's population currently stands at 5,234,000,000, an increase of nearly a quarter of a billion people since it passed the 5 billion mark just two years ago, the Population Reference Bureau said.
"It appears quite possible that the sixth billion will be attained in rec-ord time - just 10 years," said bureau demographers Carl Haub and Mary Kent in a statement released with PRB's new "World Population Data Sheet."The Population Reference Bureau is a private non-profit research organization specializing in information on population.
The demographers Tuesday said world population growth slowed in the 1970s but accelerated again during the 1980s and as the decade draws to an end is growing 1.8 percent annually, the highest rate of the decade.
Haub and Kent said speculation on world population requires assumptions to be made on future birth and death rates, and for some countries the assumptions may not be true.
In addition, they said, as life expectancy improves, death rates go down and without a decrease in the birth rate, the population grows faster.
"Birth rates have dropped in some developing countries, such as Thailand, China and Indonesia," they said, "but there is little evidence of change in others.
"Even to reach a stable world population size of 10 billion, double the current total, birth rates will have to begin a steady descent soon," they said. "Unless we see declines in high fertility rates in many African and Asian countries during the 1990s, the prospect for world population to level out at less than 10 billion seems very dim.
"As far as ultimate world population size is concerned, the 1990s will truly be a decade of decision," they added.
-Most populous in 1989: China, 1,103,923,000. It is projected to reach 1,523,233,000 in 2020.
-Second: India, 835,035,000; will grow to 1,374,470,000 in 2020.
-Third: Soviet Union, 288,742,000; will reach 355,093,000 in 2020.
-Fourth: United States, 248,806,000; in 2020, 294,364,000.