(MENAFN- AFP) The number of people globally aged 65 and over is expected to more than double by 2050 as the world's senior population continues to rocket, a US study says.

The global population is aging at an unprecedented rate with 8.5 percent of people worldwide -- or more than 600 million -- now aged 65 and over, said the US Census Bureau report.

If the trend continues nearly 17 percent of the global population, or 1.6 billion people, will be in the 65-and-over age bracket by 2050.

"People are living longer, but that does not necessarily mean that they are living healthier," said Richard Hodes, director of the National Institute on Aging (NIA), which commissioned the study, "An Aging World: 2015."

"The increase in our aging population presents many opportunities and also several public health challenges that we need to prepare for."

"NIA has partnered with census to provide the best possible data so that we can better understand the course and implications of population aging."

By 2050, global life expectancy at birth is projected to increase by almost eight years, from 68.6 years in 2015 to 76.2 years, the study said.

The global population of the "oldest old" -- people aged 80 and older -- is expected to more than triple between 2015 and 2050, from 126.5 million to 446.6 million.