Status Updates From Predicting Our Climate Futu...

The problem is that emissions don’t tell us concentrations.

…small differences in the representation of a dynamical system like a climate model could potentially lead to it giving very different probabilistic predictions: different probabilities for future behavior. She [Dr Thompson] argued that even the smallest error in the formulation of the model could lead to different predictions for some point in the future. She gave the effect a name: the Hawkmoth effect.

These considerations of Lorenz-Stommel show us that a useful definition of the climate of the future is the probability distribution of future climatic behaviors in the light of our knowledge of the state of the climate system today: a more specific version of ‘climate is what we expect’.

We need to be careful — particularly with climate predictions, because the extrapolation and one-shot bet characteristics mean we have no chance of repeating the experiment and seeing how the results might actually vary. We have no chance of testing our conclusions. There’s only one twenty-first century and we don’t have the results from that yet.

“Climate change is taking us into a never-before experienced situation. Forget about repeatability — we don’t even have one observation of the behavior we are trying to predict in the future.”