Today’s a holiday, of a sort of we might best observe by trying to do exactly nothing.

Earth Overshoot Day represents the point in the year in which current consumption of water, food, energy and other resources exceeds the earth’s annual carrying capacity.

In a world where people consumed to the max but within their collective means, overshoot would arrive each year on Dec. 31. This year it comes on Aug. 19 — or Day 231, with 134 remaining on the calendar.

Earth Overshoot Day is the clever brainchild of the Global Footprint Network, whose mission is “advancing the science of sustainability.” As metric or metaphor, it’s simplicity itself, instantly intelligible to anyone who has ever had to live within budget.

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Sustainability is typically discussed in terms of current generations’ obligation to abstain from consuming resources needed by future generations. That’s a murky appeal to altruism that projects no clear point of reckoning and seems to suggest, no doubt, to some that the debt will never actually need to be repaid.

Overshoot, by contrast, makes the extent of our overconsumption perfectly plain, by placing on the calendar the approximate point at which we go into a sort of deficit spending.

It reflects the accelerating pace of consumption, too: Just five years ago, Earth Overshoot Day fell on Sept. 25. At the start of the millennium it was Nov. 1.

If the concept is simple, the calculations behind it are as complex as the problem it quantifies.

Global Footprint claims to draw upon United Nations data providing “about 6,000 data points per country per year,” as well as “some complementary data points from the most recent scientific literature,” for 230 countries, territories and regions. Available resources are aggregated into a measure of “biocapacity,” which is laid alongside aggregated consumption.

Tough trend lines

The authors do not claim to be spot on, however — asserting only that this overall calculus of resource consumption versus production is within maybe 15 percent of precisely right. Which is more than close enough to spot the trends. Which are not encouraging:

Today, 86 percent of the world population lives in countries that demand more from nature than their own ecosystems can renew. Moderate population, energy and food projections suggest that humanity would require the biocapacity of three planets well before mid-century. This may be physically unfeasible.



The costs of our ecological overspending are becoming more evident by the day. The interest we are paying on that mounting ecological debt in the form of deforestation, fresh-water scarcity, soil erosion, biodiversity loss and the build-up of CO 2 in our atmosphere also comes with mounting human and economic costs.

But this is not only a rich-country problem. While 15 percent of the world’s population lives in countries whose high income allows them to offset overconsumption with imports and other means,

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Today’s most vulnerable countries are struggling with both low income (as defined by the World Bank) and biocapacity deficits. They are home to 72 percent of the global population, including two billion people who are not able to meet their most basic needs.

Up through the 1960s, the data suggest, the world’s resources were being replenished more quickly than they were being consumed; worldwide, in 1961, the world’s population was consuming only about three-fourths of its available resources.

Different countries reached the point of overconsumption at different times, of course; according to Global Footprint’s interactive map tool, which allows a country-by-country look at the situation, the U.S. crossed the line in about 1967.

But by the 1970s, enough countries had moved from “ecological creditor” to “ecological debtor” status that the earth as a whole was overshooting its sustainable supply of critical resources.

American standards

Next time somebody lauds the current pattern of rising living standards around the world, consider this: If everyone on earth lived the lifestyle of the average American, we would need five Earths to meet the demand. (And, by my own calculation, Earth Overshoot Day would arrive around the ides of March.)

However, Americans earn better marks than many other countries in terms of living within their national means, according to Global Footprint’s calculations. We use about 1.9 times our available resources annually ( or, put another way, it would take 1.9 USAs to support current U.S. resource consumption).

Other countries with comparable lifestyles but smaller land areas and national resource bases look even more imprudent by this measure. It would take 3.3 United Kingdoms to meet current UK, consumption, for example; the UK was among a handful of countries already in deficit by 1961.

We’re also doing better than Germany (2.5), Greece (3.1), Switzerland (4.1), Italy (4.4) and Japan (7.0); not quite as well as France (1.6), Morocco (1.8), the Philippines (1.8) Turkey (1.7) and Vietnam (1.5).

Despite its huge land area, China comes in at 2.2; the United Arab Emirates is off the charts, almost, for consuming 12.3 times its own available resources every year.

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Motivating change

And some countries haven’t yet reached the point of deficit spending. Australia, Brazil, Canada, Sweden, Madagascar and Indonesia are still operating in the black in sustainability terms, although the margin in every case has shrunk since the 1960s and is shrinking still.

Global Footprint claims that its work has inspired sustainability efforts in several countries, including national land-use planning for smart growth in the Philippines, investments in sustainable agriculture systems in Morocco — even a major investment in high-efficiency electric lighting throughout the United Arab Emirates.

At the personal level, it offers an engaging interactive calculator that lets you measure your own ecological footprint in overshoot terms — that is, how many Earths we’d need if everybody ate, traveled and bought stuff the way you do — and how you could shrink it.

(I’m too embarrassed to report my own score here. I’ll just say, I’m sure glad I’m not flying anywhere for business anymore.)