Today at the ICTP workshop on e-infrastructure for climate science, George Philander gave a really thought provoking talk on global warming and aspects of policy consequences - particularly in an African context.

His basic meme followed the following line of argument:

  • We know that in pliocene times the earth appeared to be in a permanent state of El Nino (no evidence for cold water intrusions in equatorial regions).
  • No current climate model can replicate that state, so
  • We can only trust models for small perturbations from the current state
    • He alluded to a paper by Carl Wunsch pointing out that models can’t be tested in paleo times … and to a paper by Paul Valdes. I’m going to chase up both.
  • So, he worries about global warming, not because we know what is going to happen, but because we don’t, which implies that
  • this is a time for circumspection. He likens us (the planet) to a ship in fog. It’s time to slow down and sound our way!

He also had a lot to say about the policy paralysis which amongst most serious analysists comes down to an argument about the discount rate based on our current predictions for the future. Should we act now or later? But this is a rich persons argument! From those in poverty there is no argument, the only choice is later! However, the argument over discount rate is predicated on (relatively) small perturbations from the current state, but if our models don’t do serious perturbations, that’s a matter of concern. As he puts it, we will know these things, but we don’t yet, so, let’s put the argument in terms of the planet being a special place (habitable) at a special time (warm interglacial). Let’s treat that planet with some circumspection until the future is clearer!

What exactly to do, if your perspective is that of trying to lift millions from poverty, even as you want to do it without burning coal, is a moot question. I don’t think any of us know the answer - Philander certainly didn’t claim an answer - but it’s a question that I hadn’t really given any thought to before today.

Most of these ideas appear in a paper called “Where are you from? Why are you here? An African perspective on global warming.” which appears in the Annual Review of Earth and Planetary Sciences, pdf. It’s well worth a read, since amongst other reasons, you wont often see a reproduction of a Titian in the same article as a figures showing milllenial temperature changes etc. There is also a call to arms for an African centre to study earth sciences. I hope it succeeds!