Hey guys, Joe here. I’ve been thinking… if you sang happy birthday to every person who will be born today, you’d be singing for nearly six and a half weeks without stopping. That’s adding 386,000 more birthday cakes and humans, every day. It’s estimated that 1 in 15 humans ever born is alive right now. When I was growing up there were only 5 billion of us, but now Earth is home to 7.6 billion people. And some folks are worried what will happen if things continue at this rate. Space isn’t the problem. If we all lived as densely as people in Manhattan, every human could fit inside Norway, with a fjord or two to spare. But our species’ true footprint is much, MUCH larger. For many, today’s climate and ecological imbalances are proof there’s simply too many people on this planet. But are there really? What IS overpopulation? And how did it get this way? No one really asked these questions until recently, because for tens of thousands of years, our species’ numbers only hovered in the millions. But by the year 1800 or so, there were finally one billion of us, and then things really started to change.
While it took tens of thousands of years for the human population to hit 1 billion, it only took 123 years to double that, and just 47 to double again. Since the 1970s the 5th, 6th, and 7th billion have arrived every 12 years. So when does population growth become overpopulation? The answer? It depends. Way back in 1798, Thomas Malthus warned that unchecked population growth would, as a rule, outpace food supply, leading to global mass starvation and violent conflict. Many environmentalists in the 20th century predicted the incoming population bomb would send shockwaves of disease, poverty, and environmental destruction rippling around the globe, basically ruining everything. This hasn’t proven to be the case. Malthus underestimated humanity’s ability to increase Earth’s capacity using good ol’ science. But one thing is true: The way we feed 7 billion people today won’t scale to feed 10 billion tomorrow. I don’t know if you’ve noticed, but many parts of the world have too much food. Maybe we aren’t getting it where it’s needed, because we let imaginary lines on maps make too many rules. A lot of what we grow doesn’t go into our own stomachs
. A third of crops go to feeding livestock. Animals raised for food occupy 80% of Earth’s agricultural land, yet provide only 20% of our calories. Beef alone requires ten times as much land per unit of protein as produce, grains, even eggs. We’ve been able to scale up food production so far, but there is SOME upper limit to how many people Earth can feed, no matter how we grow it, and we can’t exactly eat the moon. But what makes populations grow–or not grow? The reality for most of history was that many children would die before adulthood, so you’d better have plenty. Lots of births balanced by lots of deaths kept populations low, but steady, for a long time. But beginning in the 1700s, advances in agriculture and transportation meant fewer people starved. Later, during the Industrial Revolution, public health and economic advancements translated into less disease and higher living standards. Death rates went down, but old habits die hard, so people continued to have lots of babies, which led to rapid population growth.
Eventually people caught on that more of their kids were going to survive, and as education and opportunities for women improved, families started having fewer children, and population growth slowed. Eventually, when birth and death rates remain low, populations level off, and become stable, or even start shrinking. Things had gotten a lot better for a lot of people… if they lived in Europe or North America. Not every country moves through these demographic transitions at the same time, so while population growth was slowing or coming to an end in many developed countries, it was just picking up in other places. But developing nations are moving more rapidly through these transitions. It took the United Kingdom 95 years to halve birth rates, while Brazil did it in 26, and Iran just 10. Today birth rates are falling almost everywhere.
The less time a country spends in stages of rapid growth, the quicker Earth’s population stops increasing. It’s unlikely that the 12 billionth human will ever be born. And by 2100 our population will most likely peak between 9 and 12 billion. Instead of one big population bomb, the challenge today is defusing a few population “cluster bombs” in pockets of the developing world. There are two big ways to accomplish this. Increasing women’s access to education is the most effective way to lower birth rates.
It improves children’s health and leads to better family planning. Empowering women leads to slower population growth. This alone could reduce greenhouse gas emissions as much as all wind energy by 2050. Today, the richest 10% of humans are responsible for almost half of climate emissions, while the poorest half of people are only responsible for a tenth. Developed nations will have to reduce their impact and meet developing nations in a cleaner middle. Populations can’t grow forever without consequences, but under the right circumstances populations control themselves. But 10 billion people is still a lot of mouths to feed, and doing it without ruining nature or anything like that won’t be easy.