Fast-falling birth rates and rising AIDS deaths are stifling the population explosion – and could lead to a decline in global population in the second half of the 21st century.



In new forecasts released on Wednesday evening, UN demographers cut 400 million from their best estimate of the world’s population in 2050. Joseph Chamie, the head of the UN population division in New York, said he now expected 8.9 billion people on Earth in 2050, rather than the 9.3 billion that he forecast in 2002. The current figure is 6.3 billion.



The 400-million reduction equates to the current populations of the US, Canada and Mexico combined. Chamie said half arose from birth rates falling faster than expected and the other half was due to rising forecasts of the death toll from AIDS. “HIV/AIDS is a disease of mass destruction,” he said.



The new population projections stretch to the year 2050, but not beyond. However, he warned that “fertility rates will be below replacement levels in three-quarters of the world by 2050”. The great majority of women worldwide will be having fewer than two children.