Nature | Editorial



People power

Climate models must consider how humans are responding to a warming world.

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Physics and mathematics can tell us how the Universe began, but as the cosmologist Stephen Hawking noted: “They are not much use in predicting human behaviour because there are far too many equations to solve.”

The motives, needs and desires that drive human action have long resisted rational analysis. From the volatility of the stock market to fads and fashions that flare brightly and then vanish, the ability of individuals to act unpredictably has undermined attempts to model their behaviour with any level of precision.

The science-fiction writer Isaac Asimov had the right idea. If one considers a sufficiently large population of people, he wrote, then just as the mass movement of a gas can be inferred through simple calculations — whatever the individual molecules might do — so too can the future actions of a large population.

Asimov called his fictional science of predicting people’s behaviour psycho­history. He used it as a central plank of his classic Foundation series of books. The predictions of psychohistory were more than a model, they were a set of instructions for how future societies must respond to a predictable crisis they helped to create.

In a Comment on page 365, Paul I. Palmer and Matthew J. Smith call for human adaptation to climate change to be modelled to help avert a real-life predictable crisis. Existing models of the planet’s changing climate are insufficient, they argue, because they leave out the people. Omitting human behaviour from these mathematical studies, they write, is like “designing a bridge without accounting for traffic”.

Societies will be different in a warmer world, they point out, and we should understand how this will unfold. It is, in essence, another feedback in the climate system, and one that should be quantified and accounted for. Perhaps another seven billion equations will need to be added to the mix.

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2 comments Subscribe to comments

  1. Avatar for Keith Alverson
    Keith Alverson
    The author of this intro does not seem to have gotten the message from Azimov's book. The main point was that psychohistory did not work, because an unexpected scenario not in the algorithm (the mule) caused everything to go haywire. With regard to the original comment, sure, model the traffic on the bridge, but did you remember to model, say, the terrorist that blows it up one day? The authors have certainly identified a good point - that there is a big feedback on climate due to human adaptive actions. However the idea we can bung these into a numerical model algorithm with only 'three main things' being needed (interdisciplinary research, computational and conceptual frameworks and more data) sounds like academic hubris to me.
  2. Avatar for Michael Lardelli
    Michael Lardelli
    Climate models should also incorporate rational (rather than economics-based) estimates of accessible fossil fuels. For example: Ward, J.D., S.H. Mohr, B.R. Myers and W.P. Nel (2012) High estimates of supply constrained emissions scenarios for long-term climate risk assessment, Energy Policy 51, 598-604.
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