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Friday, May 18, 2007

I=PAT is rubbish I=PA/T

Wikipedia says

I = P × A × T

Human Impact (I) on the natural environment equals the product of population (P), affluence (A; consumption per capita) and technology (T: environmental impact per unit of consumption).

This describes how our growing population, affluence, and technology contribute toward our environmental impact.

The equation was developed in the 1970's during the course of a debate between Barry Commoner, Paul R. Ehrlich and John Holdren


This is one of the staple equations of the "environmental movement", perhaps the satple, despite the fact that Impact & Technology are virtually impossble to measure numerically & Affluence little moreso.

However the main point has to be that technology, because it is how we manipulate the world to produce ever greater effects with the same inputs is not a multiplier of impact but a divider. High technology produces more efficiently per unit (it may thus allow to produce more units which means wealth but that is an increase in affluence & doesn't change the basic effect). If higher technology requires less inputs it is, by definition, an impact divider rather than multiplier.

As Doctor Emmit Brown said in Back to the Future II when it was suggested they deliberatley fly into the baddies car "that is a 1950s Chevrolet, this is a state of the art DeLorean - they'd go through us like paper". 1950s cars did use so much more steel because they were lower technology.

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