The global population is projected to balloon to between 9 and 13.2 billion people by 2100, driven by a population explosion in Africa.

Few people in the developed world consider the sheer number of human beings inhabiting our planet, unless of course they’re stuck in traffic or waiting in line at their favorite restaurant.

But United Nations experts say stabilizing the world’s population in the 21st century is unlikely, and the rate at which humans are reproducing will present serious problems that could tax resources and compromise human health.

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There are currently 7.2 billion people on Earth, but new projections using data from the UN show there’s a 95 percent chance that the population will expand to between 9 and 13.2 billion by the year 2100.

Africa is expected to see the greatest rate of growth. Experts estimate with 95 percent confidence that Africa’s population will rise from one billion to between 3.1 and 5.7 billion by 2100, bringing the population density in Africa to the level of China today. The findings were published today in the journal Science.

Experts attribute three-quarters of the increase in population growth to people having more children that live longer. Other areas of the globe, such as Asia and Latin America, have been experiencing birth rate drops since 1950, researchers said.

Asia is expected to peak at 5 billion people in 2050, and North America, Europe, and Latin America and the Caribbean are expected to remain below 1 billion people each.

“In a given year and country the fertility rate might be half a child higher, but the probability that it would be half a child higher in all countries in all years in the future is very low,” corresponding author Adrian Raftery, a professor of statistics and of sociology at the University of Washington, said in a statement.

In Africa, where contraceptives are often scarce and expensive, the median number of children per woman is 4.6. Population growth in Africa — with limited available resources to provide for more people — contributes to poor living conditions, famine, and the spread of diseases like malaria and Ebola. West Africa is currently in the midst of the worst Ebola virus outbreak in history.

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“We don’t live on Planet Africa. We live on Planet Earth. This is everyone’s problem,” Camilo Mora, a population expert and assistant professor of geography at the University of Hawaii at Manoa, told Healthline. “We don’t really need to make any prediction because we can see it right now. We don’t really need to look that far into the future to see the consequences of overpopulation.”

The new report concludes that the growing global population will require new environmental, economic, health, governmental, and social policies.

“We need to get serious about this. This isn’t a joke anymore,” Mora, who wasn’t involved in the new research, said. “We need a broader sense of responsibility when having children. When you bring that into a conversation, people are going to be offended, but we need to have this conversation.”

A growing concern is the number of working-age individuals who are able to support elderly members of society, especially as humans continue to live longer with new medical advances. Developed countries, such as Germany and the United States, are expected see the ratio of workers to retirees cut in half over time.

The key isn’t merely having more working-age people, but having people with the education and ability to work high-quality jobs that can support strained economies, Mora said. This involves government investment in education, family planning services, and more.

“At the end of the day, it comes down to you and I taking responsibility. We’re not saying don’t have children. We’re saying think about the consequences of having that many children,” Mora said. “We have to ask, do we want a crowded planet or a better planet?”

The ballooning global population boils down to two issues, Mora said. One is the need to consider what it means to have more children than will simply replace you. In the past, the average family included 2.1 children, with two children to replace the parents and 0.1 to account for the infant mortality rate. Now, with more medical advances, experts recommend one child for every two parents.

The second issue is ensuring that people have access to contraceptives. This means making them available, affordable — or free in impoverished areas — and socially acceptable to use regularly.

“We need to provide those resources and allow them to use it, which will need change in religion or social barriers,” Mora said.

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