Within the next ten years – and for the first time ever – there will be more pensioners on the planet than children under the age of five. So says the US Census Bureau, which reports that, every month around the world, 870,000 people turn 65.

Richard Suzman, from the National Institute of Ageing in Maryland, which commissioned the study, said: “Global ageing is changing the social and economic nature of the planet.

“The fact that, within ten years, for the first time in human history, there will be more people 65 and older than children under five in the world, underlines the extent of this change.”

European and North American populations have been steadily ‘going grey’ for decades, but the trend is now affecting developing regions, especially Asia. Rising life expectancy, better health care and lower fertility rates mean some Asian nations can expect rises in pensioner populations. The study shows that, in China, the number of over-65s will more than triple from 106 million today to 329 million by 2040 – affecting the country’s economy as the working population depletes. The number of pensioner South Koreans will also increase three-fold, from ten to 29 per cent, while Singapore ‘greys’ will rocket from nine per cent now to 33 per cent in 2040.

Life expectancy is rising strongly almost everywhere, says the report – with the exception of Zimbabwe, where Aids and starvation mean most people die before they turn 40.

The report says 62 per cent – 313 million – of the world’s over-65s live in developing nations. By 2040, this figure is projected to top one billion. The numbers of people over the age of 80 are multiplying faster than any other age group, and this elderly set is predicted to grow by 233 per cent.