Saturday, April 18, 2009

Consumption, Not Population Is Our Main Environmental Threat

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Another great photo by Peter Menzel. Check out his galleries.

Fred Pearce writes that

"It's overconsumption, not population growth, that is the fundamental problem: By almost any measure, a small portion of the world's people — those in the affluent, developed world — use up most of the Earth's resources and produce most of its greenhouse gas emissions."


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13 Apr 2009: Yale Environment 360

Consumption Dwarfs Population
As Main Environmental Threat


by Fred Pearce

It’s the great taboo, I hear many environmentalists say. Population growth is the driving force behind our wrecking of the planet, but we are afraid to discuss it.

It sounds like a no-brainer. More people must inevitably be bad for the environment, taking more resources and causing more pollution, driving the planet ever farther beyond its carrying capacity. But hold on. This is a terribly convenient argument — “over-consumers” in rich countries can blame “over-breeders” in distant lands for the state of the planet. But what are the facts?

The world’s population quadrupled to six billion people during the 20th century. It is still rising and may reach 9 billion by 2050. Yet for at least the past century, rising per-capita incomes have outstripped the rising head count several times over. And while incomes don’t translate precisely into increased resource use and pollution, the correlation is distressingly strong.

Moreover, most of the extra consumption has been in rich countries that have long since given up adding substantial numbers to their population.

By almost any measure, a small proportion of the world’s people take the majority of the world’s resources and produce the majority of its pollution. Take carbon dioxide emissions — a measure of our impact on climate but also a surrogate for fossil fuel consumption. Stephen Pacala, director of the Princeton Environment Institute, calculates that the world’s richest half-billion people — that’s about 7 percent of the global population — are responsible for 50 percent of the world’s carbon dioxide emissions. Meanwhile the poorest 50 percent are responsible for just 7 percent of emissions.

Although overconsumption has a profound effect on greenhouse gas emissions, the impacts of our high standard of living extend beyond turning up the temperature of the planet. For a wider perspective of humanity’s effects on the planet's life support systems, the best available measure is the “ecological footprint,” which estimates the area of land required to provide each of us with food, clothing, and other resources, as well as to soak up our pollution. This analysis has its methodological problems, but its comparisons between nations are firm enough to be useful.

They show that sustaining the lifestyle of the average American takes 9.5 hectares, while Australians and Canadians require 7.8 and 7.1 hectares respectively; Britons, 5.3 hectares; Germans, 4.2; and the Japanese, 4.9. The world average is 2.7 hectares. China is still below that figure at 2.1, while India and most of Africa (where the majority of future world population growth will take place) are at or below 1.0.

The United States always gets singled out. But for good reason: It is the world’s largest consumer. Americans take the greatest share of most of the world’s major commodities: corn, coffee, copper, lead, zinc, aluminum, rubber, oil seeds, oil, and natural gas. For many others, Americans are the largest per-capita consumers. In “super-size-me” land, Americans gobble up more than 120 kilograms of meat a year per person, compared to just 6 kilos in India, for instance.

I do not deny that fast-rising populations can create serious local environmental crises through overgrazing, destructive farming and fishing, and deforestation. My argument here is that viewed at the global scale, it is overconsumption that has been driving humanity’s impacts on the planet’s vital life-support systems during at least the past century. But what of the future?

We cannot be sure how the global economic downturn will play out. But let us assume that Jeffrey Sachs, in his book Common Wealth, is right to predict a 600 percent increase in global economic output by 2050. Most projections put world population then at no more than 40 percent above today’s level, so its contribution to future growth in economic activity will be small.

Of course, economic activity is not the same as ecological impact. So let’s go back to carbon dioxide emissions. Virtually all of the extra 2 billion or so people expected on this planet in the coming 40 years will be in the poor half of the world. They will raise the population of the poor world from approaching 3.5 billion to about 5.5 billion, making them the poor two-thirds.

Sounds nasty, but based on Pacala’s calculations — and if we assume for the purposes of the argument that per-capita emissions in every country stay roughly the same as today — those extra two billion people would raise the share of emissions contributed by the poor world from 7 percent to 11 percent.

Look at it another way. Just five countries are likely to produce most of the world’s population growth in the coming decades: India, China, Pakistan, Nigeria, and Ethiopia. The carbon emissions of one American today are equivalent to those of around four Chinese, 20 Indians, 30 Pakistanis, 40 Nigerians, or 250 Ethiopians.

Even if we could today achieve zero population growth, that would barely touch the climate problem — where we need to cut emissions by 50 to 80 percent by mid-century. Given existing income inequalities, it is inescapable that overconsumption by the rich few is the key problem, rather than overpopulation of the poor many.

But, you ask, what about future generations? All those big families in Africa begetting yet-bigger families. They may not consume much today, but they soon will.

Well, first let’s be clear about the scale of the difference involved. A woman in rural Ethiopia can have ten children and her family will still do less damage, and consume fewer resources, than the family of the average soccer mom in Minnesota or Munich. In the unlikely event that her ten children live to adulthood and have ten children of their own, the entire clan of more than a hundred will still be emitting less carbon dioxide than you or I.

And second, it won’t happen. Wherever most kids survive to adulthood, women stop having so many. That is the main reason why the number of children born to an average woman around the world has been in decline for half a century now. After peaking at between 5 and 6 per woman, it is now down to 2.6.

This is getting close to the “replacement fertility level” which, after allowing for a natural excess of boys born and women who don’t reach adulthood, is about 2.3. The UN expects global fertility to fall to 1.85 children per woman by mid-century. While a demographic “bulge” of women of child-bearing age keeps the world’s population rising for now, continuing declines in fertility will cause the world’s population to stabilize by mid-century and then probably to begin falling.

Far from ballooning, each generation will be smaller than the last. So the ecological footprint of future generations could diminish. That means we can have a shot at estimating the long-term impact of children from different countries down the generations.

The best analysis of this phenomenon I have seen is by Paul Murtaugh, a statistician at Oregon State University. He recently calculated the climatic "intergenerational legacy" of today’s children. He assumed current per-capita emissions and UN fertility projections. He found that an extra child in the United States today will, down the generations, produce an eventual carbon footprint seven times that of an extra Chinese child, 46 times that of a Pakistan child, 55 times that of an Indian child, and 86 times that of a Nigerian child.

Of course those assumptions may not pan out. I have some confidence in the population projections, but per-capita emissions of carbon dioxide will likely rise in poor countries for some time yet, even in optimistic scenarios. But that is an issue of consumption, not population.

In any event, it strikes me as the height of hubris to downgrade the culpability of the rich world’s environmental footprint because generations of poor people not yet born might one day get to be as rich and destructive as us. Overpopulation is not driving environmental destruction at the global level; overconsumption is. Every time we talk about too many babies in Africa or India, we are denying that simple fact.

At root this is an ethical issue. Back in 1974, the famous environmental scientist Garret Hardin proposed something he called “lifeboat ethics”. In the modern, resource-constrained world, he said, “each rich nation can be seen as a lifeboat full of comparatively rich people. In the ocean outside each lifeboat swim the poor of the world, who would like to get in.” But there were, he said, not enough places to go around. If any were let on board, there would be chaos and all would drown. The people in the lifeboat had a duty to their species to be selfish – to keep the poor out.

Hardin’s metaphor had a certain ruthless logic. What he omitted to mention was that each of the people in the lifeboat was occupying ten places, whereas the people in the water only wanted one each. I think that changes the argument somewhat.

* * * * *

Gary Peters strongly objects, "Nothing in human nature bodes well for cutting consumption levels in the short run — people want more, whether they need it or not, and billions on Earth really do need more."


Fred Pearce has done us no favors by downplaying population numbers and growth then pretending that only overconsumption by a small minority is the real force behind the growth in greenhouse gases and climate change.

As Paul Ehrlich and others have noted for decades, human impact on the environment is multiplicative. In his I = PAT equation he gave weightings to population, affluence, and technology as they impact the environment. From a climate change perspective we could rewrite this in different ways, but it would be moronic to leave population out of the equation.

Let's start with this rewrite. GGE = PCF That is greenhouse gas emissions (GGE) = population (P), per capita consumption (C), and energy produced from fossil fuels (F). We could diddle with this, but it contains the basics. Now let's consider Fred's notion that population doesn't matter, a view held by many economists among others, but a view held by no ecologist that I can name.

Greenhouse gas emissions are going to continue to grow so long as any one of these three variables continue to grow, P, C, or F. P continues to grow at about 80 million per year and has increased from 1.6 billion in 1900 to 6.8 billion today. C continues to grow virtually everywhere where that is possible because few if any people anywhere are "satisfied" with their current levels of consumption. Barring disaster, then, C will continue to grow as well. With both P and C growing, reductions in GGE will have to come from sharp reductions in F, fossil fuel usage.

That may happen, but not soon enough to keep the Earth's atmosphere from having a CO2 level in perhaps the 500-600 ppm range (or more), up from close to 390 ppm today and perhaps twice the 270 ppm that prevailed at the beginning of the industrial era.

Because their supplies are finite, fossil fuels sooner or later will face declining production, probably with concomitant rising prices, and GGE will finally level off, then drop.

Is that enough? Not if the vast majority of climatologists, including those at the IPCC, are right, or even close. Because much of the increase in productivity that has allowed rapid population and consumption growth to occur over the last century has come directly from our discovery and use of fossil fuels, we should expect productivity declines to set in as fossil fuels become scarcer unless we can truly replace them at a sufficient scale, which right now looks unlikely.

Nothing in human nature bodes well for cutting consumption levels in the short run — people want more, whether they need it or not, and billions on Earth really do need more. However, as the EROEI for fossil fuels, first for oil and natural gas, then for coal, falls, the likelihood of production decreases will rise. At that point, with ever more people, we will start to see declines in the standard of living. By then, cutting people may no longer be an option, so population declines will set in, mainly in poor countries.

Would it not be much easier to start now to curtail future population growth, so that if production declines do set in we could decrease consumption growth and not cut population numbers? As Kenneth Boulding observed several decades ago, "Anyone who believes that exponential growth can go on forever in a finite world is either a madman or an economist." We cannnot pretend that population growth is not part of the problem, though I would be happy to admit that the additional 3 million plus added to the U.S. population each year is more problematic for the environment than 3 million additional people in Bangladesh or Sub-Saharan Africa, but that is not the whole point, Fred. More people are going to provide more environmental stress, no matter where they are born or where they subsequently move to.
(Comment posted by Gary Peters on 17 Apr 2009)

Go to original article for more discussion

And Andrew Revkin's Dot.Earth exploration of The Endless Pursuit of Unnecessary Things is a must read.

My personal strongly-held non-scientific speculation is that, while it is absolutely true that both population and consumption are problematic, it is consumption that drives destruction. As development and improved quality of life delivers the impoverished from wretchedly oppressive conditions, it also increases the cumulative ecological footprint. The riddle of combining sustainability and social justice has yet to be solved. This is THE work of the 21st Century.

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