Science writer Fred Pearce has been taking up a worthy cause over the last year: persuading the environmental community away from a focus on population growth and toward a focus on managing consumption. There is his book on a stabilizing global population (which I haven't read) and then a column in Grist, for yesterday's World Population Day, another in the Guardian, Prospect Magazine, and so forth. Then there's the Daily Show appearance. In other words, the message is being heard.

The basic point he's making is a rebuttal to the Malthusian line of reasoning that has popped up here and there throughout modernity. These are the guys with charts purporting to show all hell breaking exponentially loose as a result of people giving too much birth and not dying enough. Pearce thinks this threat is not only overstated - in fact, global population is likely to stabilize at around 9.2 billion due mostly to economic conditions - but, more importantly, it can divert needed attention from how we in the West are living to the mere fact that people in growing developing nations are living at all. And there are the unethical situations, the draconian sterilization regimes and such, that 'population control' advocates consistently find themselves tangled up in, whether justified or by perception alone, that do the environmental movement no good.

Pearce's detractors think he is creating an either/or dichotomy out of strategies that should be held together. It's the old I=PAT equation from the 70's. To get environmental impact (I), you multiply population (P) by affluence (A) by technology (T). Averting the environmental crisis involves a combination of all three strategies to mitigate the effects (presumably all negative) of humans living on earth. This equation may work in the abstract, but messing with the P variable becomes less than useful in practice for a variety of reasons.

Most importantly, it doesn't scale well. Population control really only makes sense at a global scale, but most sustainability solutions must be forged at much smaller scales. As a case in point, the Smart Growth Manual by Andres Duany et. al. states the very first principle as: "Inevitable Growth." This is because,

"No-growth campaigns, even when successful, tend to last one or two political terms at most, and often serve as an excuse to avoid planning altogether. When such policies are eventually reversed due to housing shortages, growth quickly resumes in its worst form."

Localized or nationalized no-growth groups may frame their message in terms of population stabilization when functionally their platform is anti-immigration. As it plays out, it becomes more about the distribution of the population - just not here - more so than the overall number of people on the planet. Far too often, the no-growth "environmentalists" lock horns with the pro-growth "capitalists" and what you get is a compromised mash-up that pays little attention to the most efficient distribution of land use and resources. Per capita consumption gets lost in the brawl.

Secondly, managing consumption is more within our realm of control as individuals and as communities than population growth is. To be effective, environmental rhetoric has to find that balance between actionable concern and despair. Like a blackjack player who's played the hand too far, once you've reached assured doom the rational response is to "eat, drink, and be merry for tomorrow we die." Why should I remember to turn the lights out when I leave the room if the world will be crushed under the weight of billions of people I will never meet? At least in the West, this approach merely externalizes the problem removing it from the realm of potential actions I may take.

And although population is expected to stabilize, there's no end in sight for consumption. As another Brit George Monbliot writes,

"People breed less as they become richer, but they don’t consume less; they consume more. As the habits of the super-rich show, there are no limits to human extravagance. Consumption can be expected to rise with economic growth until the biosphere hits the buffers."

This trend helps explain why studies have shown a correlation between the countries with the fastest growing populations and the slowest rates of carbon emission growth. Shifting blame to population growth in the global south is not only counterproductive, it's not true at all.

As I see it, urbanists are environmentalists who are unashamedly pro-human.  Cities are machines for energy, land, and water efficiency and people are their lifeblood. The fact that the global population is rapidly urbanizing, having just passed the 50% threshold, is cause for optimism about our potential to live within the earth's means at some point. An urbanist's ideal vision is not wilderness everywhere, but cities throbbing with human vitality here, productive rural areas over there, and pristine wilderness yet again over there. Humans are neither the parasites of the earth nor the paragons of the ecosystem.  Every human life is good (population) but humans do not always perform good actions (behavior) - that is where the focus needs to be.