The world's population is now odds-on to swell ever-higher for the rest of the century, posing grave challenges for food supplies, healthcare and social cohesion. A ground-breaking analysis released on Thursday shows there is a 70% chance that the number of people on the planet will rise continuously from 7bn today to 11bn in 2100.

The work overturns 20 years of consensus that global population, and the stresses it brings, will peak by 2050 at about 9bn people. "The previous projections said this problem was going to go away so it took the focus off the population issue," said Prof Adrian Raftery, at the University of Washington, who led the international research team. "There is now a strong argument that population should return to the top of the international agenda. Population is the driver of just about everything else and rapid population growth can exacerbate all kinds of challenges." Lack of healthcare, poverty, pollution and rising unrest and crime are all problems linked to booming populations, he said.

...Sub-saharan Africa is set to be by far the fastest growing region, with population rocketing from 1bn today to between 3.5bn and 5bn in 2100. Previously, the fall in fertility rates that began in the 1980s in many African countries was expected to continue but the most recent data shows this has not happened. In countries like Nigeria, the continent's most populous nation, the decline has stalled completely with the average woman bearing six children. Nigeria's population is expected to soar from 200m today to 900m by 2100.