IPAT

Last weekend my family spent a lovely weekend with some longtime friends of ours. As is typical, we started “solving the problems of the world.” In the process we talked about our reading of ecological issues, and IPAT, or a way to measure the impact of population growth and the roles that affluence and technology play in that impact.

The following formula is used by those studying such issues:

I=P x A x T or I=PAT

I = Impact
P = Population
A = Affluence (both in terms of consumption (electricity, resources, soap & water, etc.) and in terms of “capital stocks” (bikes, cars, books, house(s), etc.)
T = Technology (remember to multiply by the environmental impact of the process used to create the technology).

IPAT is often used as a way to compare various parts of the world economic systems with one another. For instance, I remember growing up to hearing arguments for voluntary population slowdown (as opposed to growth). These arguments were aimed towards people living in the two/thirds world countries. While visiting Tanzania in college I was informed that the native populations had good birth control practices until the Europeans came in and told them they were not to use them.

When comparing countries the GNP (Gross National Product) is often used for the Affluence piece, but you can use what you, yourself, are making to find your own Impact. When comparing countries with one another in terms of individual family groups (using the IPAT formula), some of the arguments I heard as a child no longer make sense.

Jim Merkel relates such a case in Radical Simplicity: Small Footprints on the Finite Earth (New Society Publishers, 2003). Merkel uses the following example, in this case skipping the Technology piece, so keeps the formula to I = P x A. He chooses two families, one from India and one from the United States. The Indian family consists of a husband, wife, and three kids. The USA family consists of a husband, wife and two kids.

According to the World Bank’s 1998 statistics, the people of India had an annual per capita GNP of US$440, while in the US it was $29,240.” (See World Bank. 2000 World Development Indications CD-ROM.)

The family in India:
I = 5 people x $440 = $2,200
The family in the US:
I = 4 people x $29,240 = $116,960

The American family has an impact 53 times higher than the Indian family, even with fewer children. Let’s say each family decided to have one less child. The Indian family would decrease their impact by $440, while the American family would decrease their impact by $29,240. Each average American has an impact equal to 66.5 people in India. This doesn’t mean that India doesn’t need to work toward smaller families; however the contribution of affluence far overshadows population when we compare these two families.
If technology is the silver bullet, then shouldn’t the American family, with its superior information and developments, have a smaller impact than the Indian family? Although technology could drastically reduce human impact, its applications in warfare, consumer goods and services, and for-profit medicine result in serious side effects. While its benefits are celebrated, its performance record is one of accelerated environmental impacts (p. 14-16).

Clearly, there is an assumption here. Each family has spent the GNP that they earned, and each family has brought into the family economy the average GNP per capita. While I cannot speak for your family, I can assure you that having a family of five, my wife and I have never brought anywhere close to $116,900 in one year. I am a pastor, who has served on minimum salary, after all. However, can we assume that a similar sized family in India has brought in $2,200 in one year? Not likely, as these figures are about averages. And they allow you to figure out quickly what your impact is likely to be. However, just by participating in the United States’ economic system, my family’s impact will be higher than the family’s in India. When I walk into a grocery store, bank, post office, etc. I am partly responsible for things I cannot control: air conditioning, automatic doors, lights on all hours, etc.

In addition, it is important to recognize that we Americans tend to spend what we make. As much, if not more, money is going out as is coming in. If you are not in this category, you can make an adjustment, but remember that figures state that close to 40% of Baby Boomers have less than $10,000 saved for retirement.*

Footprints As They Correlate to Income
Income (GNP/capita) Footprint
$100,000 and up 40 to 60 acres
$50,000 to $100,000 30 to 50 acres
$30,000 to $50,000 25 to 40 acres
$30,000 and up (Europe & Japan) 15 acres and up
$25,000 to $30,000 20 to 30 acres
$20,000 to $25,000 18 to 22 acres
$15,000 to $20,000 14 to 20 acres
$10,000 to $15,000 12 to 18 acres
$5,000 to $10,000 5 to 15 acres
$2,500 to $5,000 3 to 13 acres
$1,000 to 2,5000 2.5 to 6 acres
$500 to $1,000 2 to 5 acres
$100 to $500 1.5 to 4 acres**

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*Merkel. 83. Merkel’s figures come from Juliet Schor. The Overspent American: Downshifting and the New Consumer. New York: Basic Books, 1998.

**Ibid. 84 – Source: World Bank. World Development Indicators CD-ROM, World Bank, 2000. – and – Chambers, Nicky, Craig Simmons, and Mathis Wackernagel, Sharing Nature’s Interest: Ecological Footprints as an Indicator of Sustainability, Earthscan Publications, 2000.