The world's population could be in excess of 11 billion people by the end of this century, with experts warning the number could have serious implications for global health.
With the current world population standing at around 7.3 billion and expected to reach 9.7 billion by 2050, a United Nations study says the year 2100 could see 11.2 billion people living on the Earth.
That's a conservative estimate, with some researchers suggesting the figure could end up higher than 13 billion.
Sub-Saharan Africa will be the main driver of that extreme population growth, researchers say, as it balloons from its current 1.2 billion to a potential high of 5.6 billion.
However, Asia will remain the globe's most populous continent, they explain, with its population peaking in 2050 before dropping slightly in the decades leading to 2100.
The United Nations findings were presented at a meeting of the American Statistical Association meeting in Seattle.
A rapid decline in child mortality and an overall global increase in life expectancy are the primary factors in the population growth, says John Wilmoth, director of the population division at the United Nations.
"That's what's driving most of this," he says, citing improved health and increased longevity as great human achievements. "Sometimes people forget to see this as a sign of our success."
Still, the huge increase in the world's population will present countries around the world, especially poorer ones, with many challenges, the report authors say.
"The concentration of population growth in the poorest countries will make it harder for those governments to eradicate poverty and inequality, combat hunger and malnutrition, expand education enrollment and health systems, improve the provision of basic services and implement other elements of a sustainable development agenda to ensure that no one is left behind," they wrote.
One of the greatest needs the population explosion will create is for trained medical personnel, experts say.
An estimate prepared by the World Health Organization in 2006 suggested that to care for every 1,000 people living would require 2.3 doctors, nurses and midwives.
If world population reaches its predicted level of 9.7 billion by 2050, it will require 22 million health care professionals to care for them.
WHO has already estimated a 12.9 million shortage of qualified health care workers as early as 2035.
World population is not only growing, it is growing at the fastest rate ever seen, much faster than in the past.
For example, to grow from the one billion people living on the planet in 1804 to two billion took 123 years.
However, to increase from the five billion recorded in 1987 to six billion took just 12 years, and a figure of seven billion was reached in 2012.
