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When Did Quantitative Risk Assessment Become “Key Evidence”?

Jaime Jessop, Climate Scepticism

I noticed this tweet by Tamsin Edwards this morning, advertising for applicants for a PhD to study the possible collapse of the West Antarctic Ice Sheet.

Quite a few people took exception to the seemingly inherent alarmist message attached to the study, in particular the use of the word ‘collapse’.

If you read through the blurb, it’s hard not to get the impression that those people who would be most likely to apply to study for this PhD under the supervision of Tamsin and her colleagues would already be fairly convinced that a collapse of the WAIS at some point in the future was more probable than not due to man-made climate change. This in itself is rather worrying. Indeed, I wonder in fact whether somebody who applied to study for this PhD and who openly made it obvious that they questioned ‘catastrophic’ AGW and in particular the likelihood of a future WAIS collapse would be offered a position on the team. But maybe I’m not being very generous to Tamsin and her colleagues there, though perhaps my cynicism might be more justified with regard to the OU and the project funding board. Who knows.

But anyway, what really caught my eye was this paragraph:

“The project will run during the same period as the Ice Sheet Modelling Intercomparison Project (ISMIP6) which will inform the Intergovernmental Panel on Climate Change Sixth Assessment Report for policy makers. Results on how BISICLES behaves under climate change and modelling uncertainties will be fed into ISMIP6 and the IPCC report, providing key evidence [my emphasis] for predicting future sea level rise.”

So basically, model simulations of WAIS collapse (or not) will provide ‘key evidence’ for the IPCC’s 6th Assessment Report. I questioned Tamsin on this and she seemed to think that it was quite normal that a quantitative risk assessment generated via computer models was the equivalent of evidence. Call me old fashioned, call me out of touch, but I’m just not very comfortable with this; most especially I am not comfortable with computer model outputs generated under various hypothetical climate change scenarios being elevated to the status of key evidence in AR6.

The dictionary definition of ‘evidence’:

“the available body of facts or information indicating whether a belief or proposition is true or valid.”

We can dismiss ‘body of facts’ out of hand, because there is none, barring perhaps the initial conditions applied to the model runs. So we are left with ‘information’ which, in IPCC climate science at least, can now consist exclusively of computer generated quantitative risk assessments, whereupon plain old ‘evidence’ becomes “key evidence”.

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