The United Nations will warn this week that the world's population could more than double to 15 billion by the end of this century, putting a catastrophic strain on the planet's resources unless urgent action is taken to curb growth rates, the Observer can reveal.
That figure is far higher than many estimates - the UN had expected the world to have more than 10 billion people by 2100. There are currently nearly seven billion.
The new figure is contained in a landmark study by the United Nations Population Fund (Unfpa) to be released this week.
The report, called The State of World Population 2011, will mark the expected moment this month when somewhere on Earth birth will take the current world population over the seven billion mark, and it will be released simultaneously in cities across the globe.
Some experts reacted with shock to the figure. Roger Martin, chairman of Population Matters, which campaigns on population control, said that the Earth was entering a dangerous new phase. "Our planet is approaching a perfect storm of population growth, climate change and peak oil," he said.