The world’s population is projected to increase to 8.5 billion by the year 2030, and exceed 11 billion within the next century, a United Nations report released Wednesday said.

The report also said rapidly growing Nigeria is expected to eclipse the United States to become the third most populous country within the next 35 years.

The "World Population Prospects: 2015 Revision" also predicted that India is expected to surpass China as the most populous country within the next decade. China and India, currently the countries with the largest populations, are home to more than 1 billion people apiece. Together, they represent 37 percent of the world’s population.

The report places the current world population at 7.3 billion, and projects it will increase to 9.7 billion by 2050 and exceed 11 billion by the year 2100.

The U.S. Census Bureau currently pegs the American population at over 321 million.

The African nation of Nigeria, which is currently the seventh-largest country in the world, “is growing the most rapidly,” according to the UN, and its population is projected to surpass that of the United States by 2050 to become the world’s third-largest.

Africa has the highest current rate of population growth of any continent and is expected to account for more than half of the world’s population growth between 2015 and 2050.

“Most of the projected increase in the world’s population can be attributed to a short list of high-fertility countries—mainly in Africa—or countries with already large populations,” the UNsaid in a press release describing the report.

“Understanding the demographic changes that are likely to unfold over the coming years, as well as the challenges and opportunities that they present for achieving sustainable development, is key to the design and implementation of the new development agenda,” Wu Hongbo, UN Undersecretary-General for Economic and Social Affairs, said in a press release.

Global aging is also examined in the report. The number of people aged 60 and over should more than double by 2050, it said. The report projects Europe will lead the way in that category, with more than 34 percent of people there expected to be over 60 years old by 2050.

“The concentration of population growth in the poorest countries presents its own set of challenges, making it more difficult to eradicate poverty and inequality, to combat hunger and malnutrition, and to expand educational enrollment and health systems, all of which are crucial to the success of the new sustainable development agenda,” said John Wilmoth, Director of the UN’s Population Division.

Fox News’ Jonathan Wachtel and the Associated Press contributed to this report.