To everyone’s great relief (Paul’s and Anne’s included), Ehrlich’s Hell didn’t happen, at least not globally, and at least not yet, for reasons we’ll talk about towards the end of this chapter. It hasn’t even happened in India – cities like Bangalore are vibrant, thriving places; crowded yes, but exciting and full of opportunity too. The basic point made in The Population Bomb, though, and which Paul and Anne continue to make, remains a fact. There are biological limits for the human species, just as there are for every other species, our incredible technological achievements notwithstanding. And the world is moving towards those limits all too fast.
Here are the sobering realities. After we had colonised all the continents except Antarctica, the prehistoric human population averaged somewhere around ten million. It took thousands of years, until the early twentieth century, to grow to two billion, which is the number of people the Earth is thought capable of supporting without further major technological interventions. With those interventions, our population has almost quadrupled just since our great-grandparents’ time, to more than seven billion of us today. If we humans, averaged worldwide, continue to grow our population at the rate we’ve done over the last decade, our numbers will rise to over twenty-seven billion by the year 2100.
Few, if any, people who make their living studying biology think that can actually happen, as we’ll elaborate upon in later chapters. For one thing, there is not enough land to grow food, or enough fish in the sea, to feed that many people. For another, wars, disease and other catastrophes would almost certainly knock the human population back to significantly smaller numbers long before we hit twenty-seven billion – that is, sometime in the next few decades – as past history is all too clear in showing us. The infamous Black Death of the fourteenth century killed an estimated 30 to 60 per cent of Europe’s population; the one–two punch of the First World War and the 1918 flu pandemic may have wiped out as much as 9 per cent of all the people in the world; and the Second World War felled as much as 4 per cent. Basically, as we tried to keep growing to twenty-seven billion, we’d be packed so tight that we would be like too many rats in too small a cage, and nature’s version of population control would kick in. Ehrlich’s Hell would almost certainly spread far and wide.
What does look inevitable, though, based on just about any reasonable population-growth model out there, is that we’re destined to see a world with somewhere between nine and ten billion people by the year 2050, as we’ll explain in a little more detail below. That virtual certainty means the world you’ll be living in by mid-century is going to be very different from the one you are used to now. The big picture is that we have to pack a couple of billion more people into the relatively small proportion of Earth’s land that is available for occupation. That’s actually only about 20 per cent of the planet’s land surface, which is what’s left over after you subtract the 40 per cent we need to grow food and the 40 per cent that is such inhospitable terrain – rugged mountains, barren deserts, glaciers – that it can’t be heavily populated. The upshot is that if you like rural living, kiss it goodbye; those wide-open spaces peppered by just a few houses will be no more. City life will even more resemble living in a sardine can. As Paul Ehrlich put it: ‘People, people, people, people’.
To set what is going to happen in perspective, just think about current population densities. In 2013 India packed in (on average) about four hundred people per square kilometre, compared to the United Kingdom’s 260, and the United States’s thirty-two. By 2050, on average we’ll see India’s population density everywhere we can easily live. Of course, most people are crammed into cities, where population densities are off the charts compared to averages for a whole country. Greater Los Angeles has 1,400 people per square kilometre, greater Beijing 3,200, greater London 5,600, the New York metropolitan area 10,600, and Delhi twelve thousand. All you have to do is walk down a main street in any one of those cities – or worse yet, try to drive down one of them – to get a sense of what such population densities really mean for a way of life. Yet children growing up now are likely to look back when they are adults, and remember the cities of today as being sparsely populated. The United Nations estimates that by the year 2050, 70 per cent of humans, up from today’s 50 per cent, will be urban dwellers – that is, 6.4 billion city folk versus the present 3.3 billion. Almost double the number of shoulders to jostle you as you try to walk down the pavement.
If you’re from a developed country, as most of you reading this book probably are, and especially if you already live in a city and are pretty happy there, most things you’ve heard about population growth may well make it sound like somebody else’s problem. After all, in developed countries, we like to think we’ve got fertility rates pretty much under control (although that’s actually not the case in the United States, as we’ll see). You probably already know that it’s in poor countries that the population is growing fastest, and sad as it is to hear about deteriorating conditions on the other side of the world, you may think that things aren’t apt to change all that much where you live. But if you reflect a little more deeply on that assumption, you’ll realise you are already experiencing the impacts of population growth.
Here is one example from our own lives. It is a first-world problem, for sure, but it is illustrative in showing how growing numbers of people influence nearly everything. Emma and Clara have grown up a lot since they travelled to India with us. They’ve both finished high school and have gone off to college, but the angst of their college application process is recent enough that it still lingers in our minds. We are not alone there: college application angst infects millions of American households each year. But the elevated stress of that whole process is a new thing, because competition for college slots is just so fierce these days. Back when we were of high-school age, you threw in one or two applications, maybe three if you were really motivated, and you didn’t worry too much, because, assuming you had decent grades and hadn’t done anything too egregious, your chances of getting into where you applied were pretty good, even in top-tier universities. We’ll use Stanford University as an example, simply because we live next door to it and Liz works there. About 22 per cent of 9,800 applicants were admitted in 1970.
Back then, we (and certainly not our parents) never thought to track those percentages (or of applying to Stanford, for that matter). But today, things have changed. High-school students and their parents are well aware that in 2013, only 5.7 per cent of nearly thirty-nine thousand applicants were admitted to Stanford, and in 2014 it was even worse: 5.1 per cent of 42,167 applicants. That’s not confined to top-tier universities; it’s a global trend. In fact, what’s going on with Stanford applications is mild compared to what’s happening at top-level universities in highly populous places like India, which are routinely turning away 98 per cent of their applicants. The Indian Institute of Technology usually receives up to five hundred thousand applications, and accepts only 2 per cent of them; Shri Ram College of Commerce, part of the University of Delhi, has just four hundred slots for twenty-eight thousand applicants – only 1.4 per cent.
Those kinds of numbers are what cause stress levels in American households with high-school-age children to go through the roof each college-application season. Families (at least, the relatively few who can afford it) spend thousands of dollars to increase their children’s SAT and ACT scores by a few points, and then hundreds more dollars for them to apply to a dozen or more colleges, all carefully vetted and sorted into the categories of ‘reach’, ‘target’ and ‘safety’ schools. The reality is that the chances of getting into your top choice are slim at best, and random chance often dictates acceptance even into the safety schools. The net effect is that among high-school students (and their parents not infrequently get in on the act as well), competition can be fierce for grades, recommendations, internships, sporting teams and those other coveted achievements that make a college application stand out.
All this stress goes right back to the fact that there are so many more people in the world nowadays. Despite universities increasing their class sizes to provide places for more students, there just isn’t enough money, available classroom and lab space or land to make it possible for universities to accept much higher percentages of the applicant pool. More people apply each year in part because there are simply more students of college age each year. Over the same time that applications to places