Earth now has 8 billion people—and counting. Where do we go from here? (nationalgeographic.com)
It took humans more than 300,000 years to reach the first billion - in 1804. The most recent billion took only 12 years.
The growth in population is uneven, with some countries seeing stagnant or negative growth, while others are growing at a more rapid pace. Japan could see declines in population, and even China may see declines. Meanwhile, global warming could make some areas uninhabitable (such as the Middle East). The wealthier countries have supplemented population losses by welcoming immigrants, although that's become a political hot button issue. Other countries, such as Japan, tend to be xenophobic and unwelcoming towards immigration.
What is the ideal population for the planet? How many people is enough? How many is too much?
It took humans more than 300,000 years to reach the first billion - in 1804. The most recent billion took only 12 years.
From the emergence of Homo sapiens, it took roughly 300,000 years before one billion of us populated the Earth. That was around 1804, the year morphine was discovered, when Haiti declared independence from France, and when Beethoven first performed his Third Symphony in Vienna.
We’ve added our most recent one billion more just since the first term of U.S. President Barack Obama. A mere dozen years after reaching seven billion, the planet most likely will surpass eight billion people sometime around mid-November, the United Nations estimates based on its best demographic projections.
The actual timing, however, is uncertain. In parts of the world, census data is decades old. During COVID-19 it was virtually impossible for some countries to record every death. Even sophisticated computer models may be off by a year or more. It’s not as if anyone has done a global person-by-person head count.
But the UN is declaring November 15 as the “Day of Eight Billion” because there is no mistaking the import of this moment. Humans everywhere are living longer, thanks to better health care, cleaner water, and improvements in sanitation, all of which have reduced the prevalence of disease. Fertilizers and irrigation have boosted crop yields and improved nutrition. In many countries, more children are being born, and far fewer are dying.
Of course, the challenges we face as the world’s population continues to rise also are significant. Pollution and overfishing are degrading many areas of the oceans. Wildlife is disappearing at an alarming clip, as humans wipe out forests and other wildlands for development, agriculture, and commercial products made from trees. A changing climate driven by a global energy system that is still overwhelmingly powered by fossil fuels is fast becoming the greatest threat in history to biodiversity, food security, and access to water for drinking and farming. And that’s with the number of people we already have.
The risks and opportunities of our population boom and parallel resource crisis depend largely on decisions we’ve not yet made. Which will control our future more—the billions of mouths we’ll have to feed, or the billions more brains we could employ to do so?
“The exact impacts on future human life, I think, are still somewhat yet to be determined,” says Patrick Gerland, who oversees population estimates for the United Nations' Department of Economic and Social Affairs.
“So far, the overall experience is that the world has been successful in adapting and finding solutions to our problems,” Gerland says. “I think we need to be somewhat optimistic.”
But he quickly concedes that climate change is a powerful threat. “Simply maintaining the status quo and doing nothing is not an option,” he says. “Whether we like it or not changes will be happening, and the situation will not improve by itself. There is a need for current and future interventions.”
In the meantime, our overall population explosion belies vastly different types of demographic change taking shape around the globe. And the world’s top demographers don’t agree on just where our population is headed from here.
Meanwhile Seattle’s Institute for Health Metrics sees population peaking at roughly 9.7 billion in 2064, but dropping down to 8.8 billion, possibly less, by century’s end. Populations could fall by half across nearly two dozen countries, including Bulgaria and Spain. A lot of the difference is based on a complex method the researchers use to estimate future birth rates.
In addition to the differences between models, all of the researchers agree that efforts so far to incorporate climate change into future population projections have been inadequate. In part that’s because the potential effect largely depends on how quickly the world reduces greenhouse gas emissions. But part of the difficulty also lies in assessing climate impacts. Extreme heat could make parts of the Middle East, sub-Saharan Africa, and India uninhabitable. Storms could worsen food security. How will people respond to sea-level rise in heavily populated coastal regions?
“No one is doing this in the right way at the moment,” says Stein Emil Vollset, who oversees IHME’s population estimates.
And aside from global population estimates, climate change and politics also will likely greatly influence migration between countries. Population in the U.S. and Western Europe has been largely sustained by immigration, but it has become a political hot button. Other countries with declining populations, such as Japan, have been even more reluctant to welcome immigrants.
Yet the lopsided trends, between booming and declining populations, exacerbated by climate change, will almost certainly increase migration pressure almost everywhere.
“The only way we can get out of this demographic imbalance,” Vollset says, “is well-managed international collaboration.”
The growth in population is uneven, with some countries seeing stagnant or negative growth, while others are growing at a more rapid pace. Japan could see declines in population, and even China may see declines. Meanwhile, global warming could make some areas uninhabitable (such as the Middle East). The wealthier countries have supplemented population losses by welcoming immigrants, although that's become a political hot button issue. Other countries, such as Japan, tend to be xenophobic and unwelcoming towards immigration.
What is the ideal population for the planet? How many people is enough? How many is too much?