Thursday, August 25, 2011

Lisa Hymas of Grist expounds on the A in I=P*A*T

I Am the Population Problem
Both local and broad scale environmental problems often are linked to population growth, which in turn tends to get blamed on other people: folks in Africa and Asia who have "more kids than they can feed," immigrants in our own country with their "excessively large families," even single mothers in the "inner city."

But actually the population problem is all about me: white, middle-class, American me.

Steer that blame right over here.

Population isn't just about counting heads, although by this October we will be counting 7 billion of them worldwide. The impact of humanity on the environment is not determined solely by how many of us are around, but by how much stuff we use and how much room we take up. And as a financially comfortable American, I use a lot of stuff and take up a lot of room. My carbon footprint is more than 200 times bigger than that of an average Ethiopian, more than 12 times bigger than an average Indian's, and twice as big as an average Brit's.

Well-meaning people have told me that I'm "just the sort of person who should have kids." Au contraire. I'm just the sort of person who should not have kids.
I teach my environmental science students the following equation to describe environmental impact: I=P*A*T, where I is impact, P is population, A is affluence, and T is technology. It's the A and inefficient T that is multiplying the impact of the effect of the relatively small P in the developed world, especially in North America. Read the rest of the article, as the excerpt above is just the start of Lisa Hymas's explanation complete with supporting details of how this happens. It also explains why her environmental views have shaped her decision to be child-free.

If people in the developed world, but especially in North America, want to maintain anywhere near the current levels of affluence, they'd better hope that more efficient technologies can reduce the T to less than one (there is some evidence this is possible) before the resources run out, or everyone will be TSOL. Unfortunately, technology inadequate to the task is one of the barriers to sustainability, along with change resistance--but that's another lesson.

Hat/tip to unusualmusic on Dreamwidth.


  1. Oh, Math! Narb likes Math.

    Shouldn't it be I=(P*A)/T, where P, A & T are all greater than 0?

    Increases in P and A increase I, but as T increases, I should decrease. Ummm, linearly.

    Narb thinks T is a happier variable when he get to be a denominator, but no one cares about his feelings, do they? T is sad, but at least T knows he can't be zero. T stands for trash. T stands for Thumbelina. T stands for Tholian.

    1. No, Narb, nice try, but no. The equation does not give a number to technology by level of advancement, but by its efficiency. Highly advanced technologies can also increase impact, as I just pointed out when discussing fracking.