Breaking the silence

Human overpopulation drives the environmental crisis

Rewind forty years and a few days to the very first Earth Day in 1970. One topic was on everybody’s mind: the growing human population. Scientists and environmentalists, eyeing exponentially increasing numbers, made dire predictions about mass famine and warfare as humanity outstripped the planet’s ability to provide space and resources.

At the time, the human population numbered 3.6 billion.

Today, though nearly twice that number walk our Earth, discussion of the “population problem” has fallen by the wayside. Instead, we talk about renewable energy, electric cars, and reusable shopping bags — politically much safer than the hot buttons of family planning and birth rates. And, since thus far we’ve eluded a major population crash, we’ve allowed that doomsday fear to slip off our collective radar as though our ignorance will make overpopulation disappear.

There’s only one problem with this logic of avoidance: Overpopulation is the problem.

Every environmental issue humanity faces is exacerbated by our numbers. Nearly seven billion people must find food, water, and shelter every day. To varying degrees, we each consume fossil fuels and emit carbon dioxide. And we each have a reproductive drive — which is why our numbers are expected to swell to nine billion by 2050 (another 40 years from that first Earth Day).

If you’re like me, you believe that current levels of global inequality are ethically wrong — why does he drive a Hummer in Boston while she hauls water up a Kenyan hillside three times a day? — but you also aren’t too keen on giving up the trappings of your resource-intensive lifestyle. Hey, I need my laptop powered up all day, and it’s hard to pass up those California-grown strawberries at the grocery store. But in the long term, our planet can only support about 1.5 to 2 billion people — roughly a quarter of our current population, or a fifth of where we’re going — living at our consumption levels.

Look around you. Think of your family. Imagine three out of every four people, gone.

No wonder we’d rather fret over deforestation and wind farms. Thinking of how far we’ve overshot carrying capacity (the number of people the planet can support in perpetuity) is scary. Thinking of how far we will yet go before that 2050 population peak? Even scarier.

But the good news is, it’s a lot less scary than what our parents heard a few decades ago. Industrializing countries go through a demographic transition as per capita wealth increases. Infant mortality drops with better health care, and parents have fewer children, shrinking family size and arresting population growth. Most of Europe and the United States took about a century to pass through the transition in the 1800s. Today, the switch to “replacement rate” reproductive levels (about 2.1 births per woman) seems to be happening faster (on the order of twenty years) in developing countries.

In some places, though, women still have five or six children in their lifetimes. Western medicine, often freely given to save innocent children born into unthinkable circumstances, saves more lives, but also leads to a population boom while social mores (the number of children families choose to have, for example) struggle to keep up. I’m not arguing that Bill Gates stop looking for a malaria cure, or that we halt food donations — only that we must consider the demographic consequences of our actions.

Educating women should be part of every aid effort. (Women who finish school are more likely to hold jobs and earn wages that make additional pregnancies and the attendant time out of the breadwinning workforce less attractive.) And we should strive to make birth control accessible to everyone. Yes, there are some religious qualms about this, but the arguably higher moral calling is the preservation of existing human life. That means considering the long-term wellbeing of all humanity, not agonizing over the possibilities of children not yet conceived.

Measures like educating women and providing access to family planning are all about empowering people with choice. We’ve seen, time and again, these simple actions halting population growth. And, if we can get those last few conservative bastions to stop trying to outbreed one another and instead take a global perspective (yes, I know that’s asking a lot) then we will be able to halt population growth.

Coming back down again is a much different matter. We’ve seen through China’s example (the infamous one-child policy that’s produced a glut of restless, unwed young men) that top-down legislation doesn’t work. But neither does staying the course, particularly in a society that emphasizes the importance of growth and relies on an increasing supply of workers to sustain it (and the elderly, who, with more medical advances, are leading longer, healthier lives).

We must transition the frenetic pace of our society into longer-term acceptance of the status quo. Perhaps we do need to turn more towards “values” — experiences, time with friends and family — than fortunes. Only after a change of viewpoint can we accept a diminishment in our overexploitation of Earth’s resources.

For surely those resources are overexploited. While I’m not going to wax Malthusian with predictions of imminent catastrophe, the warning signs are all there. Our climate is being driven dangerously far from the norm we evolved under. Fossil fuel resources are running out. The human population is farther above carrying capacity than ever before. The potential for human tragedy is greater than ever.

Here at MIT, we’re trained to believe in ourselves and our technology to win the day. Certainly, in the past, innovation has saved us. The Industrial Revolution amped up productivity and the Green Revolution doubled our food supply (both relying heavily on fossil fuels). Yet rather than exercising restraint and adapting to new limitations, we have used these advances as a springboard to create more demand.

On the shaky foundation of nonrenewable resources, we’ve built an edifice of humanity nearly seven billion strong. Even if there were an easy way down, it would be impossible for our present society to see it. We’ve buried our heads in the sand — looking for more oil, perhaps? — and attempted to ignore the root problem by pointing fingers at the details.

But today, the population trajectory does seem to be leveling off, and a peak is in sight. Let’s put the population problem back on our agenda, and honor our faith in innovation by letting the great minds think out loud.

Holly Moeller is a graduate student in the MIT/WHOI Joint Program in Biological Oceanography. She welcomes reader feedback at hollyvm@mit.edu. “Seeing Green” runs on alternate Tuesdays.