John Woods: the Plankton Multiplier Effect

John Woods describes the Plankton Multiplier Effect, including Margaret Thatcher's enthusiastic response to the idea.

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The reason that we have a greenhouse effect is that the gases in the air change, the infrared balance, including the balance at the top of the ocean, by a few watts per square metre. And that radiation affects the turbulence just the same way the sun affects the turbulence, so just as you change the sun you get a diurnal variation in the turbulence, you turn up the infrared radiation and the turbulence gets weaker. And noticeably in the winter. And so I made models of it, and I was astonished how sensitive the turbulence is to the infrared. So the greenhouse effect is changing the depth to which the convection, the mixing, gets in winter. And that controls how much nutrients are brought up to the surface for next year’s seasonal growth, and if the mixing doesn’t get so deep there’s less nutrients for the plankton next year, so there’s fewer plankton. That’s biology. Fewer plankton means they’re using up less carbon dioxide, so the draw in of carbon dioxide from the atmosphere gets less. So if there’s more carbon dioxide in the atmosphere due to man’s pollution, it affects the turbulence which affects the nutrients which affects the plankton, so the plankton consume less carbon dioxide and so more remains in the atmosphere. That’s positive feedback, that’s the plankton multiplier and I made the model and published it and it created a – it got the front page of The Times so that’s fun. In fact the plankton multiplier was a term invented by the headline writer in The Times who was an economist; he was thinking of the economic multiplier and so I grabbed it immediately, that’s too good to miss [laughs], it was a lovely – lovely way of talking about positive feedback to the – because you can talk to politicians about a multiplier, they all think they understand economics, you can talk to them about positive feedback and ‘urgh, what’s that?’ So The Times did me an enormous service [laughs].

By making it kind of more convincing for a particular audience?

Making it a term which was familiar; it said exactly the same thing but it was a familiar term, it was in the comfort zone of the average politician, the leading ministers, they’re dealing all the time with economics, especially the treasury ones, especially the First Lord of the Treasury, Prime Minister, Margaret Thatcher loved it; she almost giggled with surprise and delight. About the plankton multiplier? Oh yeah, she loved that; I told her about it. She was just tickled pink with it. Jim Loveloc had educated her about climate plankton and so on but the plankton multiplier really got her.


  • Interviewee John Woods
  • Duration 00:03:07
  • Copyright British Library Board
  • Interviewer Paul Merchant
  • Date of interview 2/16/2012
  • Shelfmark C1379/64

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