Where it all begins – the IPAT equation


A way-out visual depiction of ‘our environmental responsibility’

So why am I such an advocate for technology solutions?… this post provides a ‘first principles’ type explanation.

The Jeffrey Sachs book from which I’ve taken the quote in my first post makes reference to a simple equation first published in the 1970s that sets out mankind’s impact upon the global ecosystem as a product of the number of people, their individual consumption, and the resource intensiveness of the technology they use:

I = P x A x T   (a.k.a. the ‘IPAT’ equation)


  • I = Impact upon the environment
  • P = Population
  • A = Affluence (which can be thought of as per capita GDP)
  • T = Technology (measured in terms of resource intensiveness)

Sachs suggests a modification to this equation that recognises the role of ‘clean technology’ in reducing mankind’s impact upon the environment:

I = (P x A) / S

where S = Sustainable (clean) technology (or technology with lower resource intensiveness than the incumbent)

Put simply, by increasing the use of clean technology, our impact on the environment can be maintained/reduced even as population and our standard of living increase – this idea underpins not only this blog but my entire working life.

Notably, the theory is not without its detractors.  One of the original authors of the IPAT equation contests the ability of clean technology to combat concurrent increases in population and standard of living.

While Sachs sets out a compelling vision for stabilisation of the world’s population, many examples exist of where economic development (or improved standard of living) is driving potentially catastrophic impacts upon the environment.

A recent example from China related to Beijing’s abominable air quality.  While there is an interesting back-story relating to air quality reports from the U.S. embassy contravening the official line being presented by the Chinese government, I can say from having visited Beijing in 2005 that the air quality was appalling by Australian standards – black lines of soot formed underneath my nostrils from simply breathing the air, even during summer when it was supposed to be better (they burn coal for residential heating during winter).

At the heart of Beijing’s air quality problems is the economic development that is resulting in pollution from industrial and transport activity along with dust-storms arising from deforestation of the surrounding countryside.  The government have basically said that economic development is the overriding priority, even if the improved living standards this delivers are being offset by the reduced living standards that accompany poor air quality.  In other words, they’ll get rich or die tryin’…. (cheers Fiddy).

If Sachs (and my adopted) theory is correct, the Chinese will be able to address their air quality issues without sacrificing economic development through increased use of clean technologies such as:

  • Cleaner vehicles (primarily through emissions standards but also through electric vehicle uptake)
  • Cleaner factories
  • Improved agricultural practices (such as GM crops)

Given the proven ability of the Chinese to implement change quickly as an outcome from their central decision-making, this is a case study worth watching (so long as their clean technology includes coming clean about the actual air quality…).


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