Saturday, July 17, 2021

Hawkmoth Emergence

You've heard of the Butterfly Effect, in which a small change in initial conditions causes big changes further down the line. Now we are witnessing the emergence of its lesser known and much darker cousin, the Hawkmoth Effect. The recent extreme weather events around the world, particularly the western Americas 'heat dome' and floods in Germany and Belgium, have prompted many people to comment that this weather was more extreme than expected from their interpretation of the climate models' outputs.

"We need to better model nonlinear events.” said Dieter Gerten, professor of global change climatology and hydrology at the Potsdam Institute for Climate Impact Research, looking at the German flooding.

Former Met Office chief scientist Prof Dame Julia Slingo told BBC News: "We should be alarmed because the IPCC models are just not good enough. We need an international centre to deliver the quantum leap to climate models that capture the fundamental physics that drive extremes. Unless we do that we will continue to underestimate the intensity/frequency of extremes and the increasingly unprecedented nature of them."

Julia Slingo calls, very properly, for vastly greater spending on climate modelling. But shear computing power is not enough by itself. Wisdom is required too.

The Hawkmoth Effect is a phenomenon described by Erica Thompson thus:

The Butterfly Effect is well-known as the sensitivity to initial conditions displayed by some dynamical systems, meaning that a small perturbation to initial conditions can result in a large change to the state of the system after some length of time (dynamical instability).

The Hawkmoth Effect, by analogy, is the sensitivity to structural model formulation, meaning that a small perturbation to the system itself can result in a large change to the state of the system after some length of time (structural instability).

Essential further reading for all who use computer models, whether they be climate models or in other fields, is the paper by Erica Thompson and Leonard Smith 'Escape from Model Land'.

A couple of weeks ago a seminar was held, now available to view on YouTube. Hosted by The Institute and Faculty of Actuaries (IFoA), it comprised a presentation by Dr Anthony Hodgson, entitled 'Systems Thinking and Tragedy of Consciousness', and discussion with Erica Thompson and Nico Aspinall of B&CE, with introduction by Tan Suee Chieh of IFoA.

Perhaps only watched by a few hundred people, this seminar occupies a small niche in the vastness of human discourse, but it is the sort of thinking presented here that may prove invaluable as we try to mitigate against and adapt to the unfolding climate crisis.

It is worth watching.




And if you came here looking to read about the other sort of Hawkmoth, well, sorry, but this is a good moment to join the very excellent Butterfly Conservation. It's all connected.


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