The Earth will be quite a bit more crowded in 2050—with nearly 2.5 billion more people than now.
A report released Wednesday by the United Nations projects the global population rising to more than 9.7 billion by 2050, up from just over 7.3 billion today.
In terms of growth, that's actually a slowdown, given that the world added 1 billion people since 2003 and 2 billion since 1990, according to the report. In almost every part of the world—even in the fastest-growing regions—fertility is on the decline. That trend is mostly expected to continue—families are expected to have fewer and fewer babies per household.
But momentum will still cause the planet's population to climb for several decades, especially in less developed countries where birthrates are highest.
More than half of the gains by 2050 will come from Africa, according to the report. The continent will add 1.3 billion people over the next few decades—roughly equivalent to the current population of China.
By 2050, 1 in 4 people on Earth will be African, and the report expects Africa to be the only region that will continue to grow after 2050.
But Africa will not be the only one growing. Asia will contribute 900 million new people in that timeframe as well, and South and Central America will contribute a smaller share.
Nine countries are expected to account for half of the world's population growth, and they're almost all in Africa or Asia: India, Nigeria, Pakistan, Democratic Republic of the Congo, Ethiopia, Tanzania, Indonesia and Uganda are expected to grow the most, roughly in that order.
The only country in the top nine located outside Africa or Asia is the United States, which in terms of gains is predicted to sit between Tanzania and Indonesia.
In contrast, Europe's population will shrink, even though the average fertility there will rise from 1.6 children per woman in 2015 to 1.8 by 2050. Europe is the only part of the world where fertility has actually risen in recent years.
Currently, the three largest countries in the world by population are China, India and the United States. By 2050, India will surpass China to become the largest country and Nigeria will surpass the United States to become No. 3.
As with any projection, the U.N. numbers are not certainties. Other factors could dramatically affect how fast countries grow, including access to contraception, or political and economic instability. But the report notes that "[c]ontinued population growth until 2050 is almost inevitable, even if the decline of fertility accelerates."