The world's population is expected to increase to 9.7 billion in 2050

The world's population is getting older and growing at a slower pace but is still expected to increase from 7.7 billion currently to 9.7 billion in 2050, the United Nations said Monday.

The U.N. Department of Economic and Social Affairs' Population Division said in a new report that world population could reach its peak of nearly 11 billion around the end of the century.

But Population Division Director John Wilmoth cautioned that because 2100 is many decades away this outcome "is not certain, and in the end the peak could come earlier or later, at a lower or higher level of total population."

The new population projections indicate that nine countries will be responsible for more than half the projected population growth between now and 2050. In descending order of the expected increase, they are: India, Nigeria, Pakistan, Congo, Ethiopia, Tanzania, Indonesia, Egypt and the United States.

In sub-Saharan Africa, population is projected to nearly double by 2050, the report said.

Undersecretary-General for Economic and Social Affairs Lu Zhenmin said in a statement: "Many of the fastest growing populations are in the poorest countries, where population growth brings additional challenges in the effort to eradicate poverty, promote gender equality and improve health care and education."

The report confirmed that the world's population is growing older due to increasing life expectancy and falling fertility levels.