Of course total population growth is part of the problem: all you need to do is see those hockey-stick-like graphs on page xv to know that one of the big reasons that exponentially more of everything (trees, minerals, fresh water, fisheries, etc.) has been used up in the last fifty years is because there are exponentially more of us. It took us two hundred thousand years (until the early 1800s) to reach 1 billion people; then a little over a century (1960) to reach 3 billion; and we've more than doubled since then, with our current 6.7 billion and counting.14
Yet historically, interventions aimed at stabilizing global population have usually been driven by those in the overconsuming regions of the world and have often ignored the fact of vastly unequal consumption patterns. Often places with the most rapidly expanding populations are using very few (too few) resources. Meanwhile the very small slice of the global population that owns most of the world's wealth (the top 1 to 5 percent) is producing the lion's share of greenhouse gases and other environmental destruction. It's important that whatever strategies we democratically decide to employ in order to stabilize population must be grounded in an unshakable commitment to human rights, especially women's rights, and equity.
We don't know what the actual carrying capacity of the planet is, but we know it isn't one inflexible number; it depends on our levels and patterns of production and consumption. That raises huge issues about equity in until the economic crash of 2008—there was more absolute growth overall: more people extracting, using, and disposing of more Stuff. (Even the decline in production from 2008 to 2009 was relatively small, and if past trends are any guide, we will revert to growth soon enough.) So the overall resource distribution and value judgments about how much is enough.
Should we be asking how many people the planet can sustain at the U.S. level of consumption or at the Bangladesh level of consumption? And, importantly, who decides the answer?
The questions are complicated, but we need to have the conversation and decide on our answers together. We need to do this because there is no doubt we will reach the planet's carrying capacity; we're heading in that direction now. And once we cross that line, it's game over: We depend on this planet to eat, drink, breathe, and live. Figuring out how to keep our lifesupport system running needs to be our number-one priority. Nothing is more important than finding a way to live together—justly, respectfully, sustainably, joyfully—on the only planet we can call home.
If what's getting in the way of that is this human invention gone haywire—the take-make-waste economic growth machine—then it's only logical to consider dismantling and rebuilding that machine, improved upon by all that we've learned over the previous decades.