Did Climate Change Cause Hurricane Beryl?

2024 07 08

Schrödinger's Climate Cat

Roger Pielke has a (typically) informative post “Schrödinger's Climate Cat” about the media narrative of attributing weather-related stories to “climate change.”  A bit of this is problematic for semantic reasons in that “climate” is just averaged weather, so the average cannot literally affect the data that make it up.  But more substantially, in the last year or so (and in marked contrast to earlier times) media HAS been saying with more frequently that “climate change” caused (even in the proper sense of the term that increased concentrations of CO2 in the atmosphere caused) this or that fire, drought or hurricane. 

Sometimes this may be qualified with a percentage probability; the event has a certain probability of having been caused by the increase in CO2 concentration in the atmosphere.  This may seem to be a virtuous display of epistemic modesty, but it cannot really be correct.  Actual events and the chain of antecedent causes either happen or they don’t. 

There _is_ a way of talking about probabilities, however, that does make sense. The mistaken ways we see may be a problem of the way the journalist has reported an expert opinion.  The sensible way of discussing probabilities is to start with a model of how CO2 concentrations affect planetary physical variables, run it with small perturbations multiple times for the case in which CO2 has increased since pre-industrial times and note the distribution of events of the sort under examination.  Then run the model multiple times for the case in which CO2 concentrations have not increased and again note the distribution of events of the sort under examination.  One can now report that the event under examination is more or less likely to have occurred in the with CO2 increase case than in the without CO2 increase case.   

But even when the event under examination is “extreme weather” (and that is well defined) something still seems off.  “Is extreme draught [or hurricanes or wildfires or crop failures] increasing?” as a stand-in for the causal question does not seem like the right question.[1] 

The question, rather, ought to be, “How does the accumulatio of CO2 in the atmosphere affect, inter alia, extreme rainfall patterns?”  And that question is only a part of the questions:

a)   “What are the net costs and benefits of different trajectories of CO2 emissions (costs such as those arising from extreme weather events) that would be the result of different policies to affect those trajectories?”  And that in turn would be embedded in the follow-up question, “Which of those policies, taking account of their cost, is best according to established criteria?”

b)   “What are the expected future effects of CO2 already emitted,” as part of the larger question, “How can we adapt to these expected effects at least cost?”   

Granted the media ask the “Does climate change cause …” question, but as we learn in media management school, when asked an improperly formulated question in good faith, we re-interpret the question as a proper one and answer THAT one.  Presumably the proper answer to “Did climate change cause/make worse this drought/hurricane/flood?” is something like, “It is hard to attribute this event to past accumulation of CO2 in the atmosphere, but its occurrence is consistent with our best models of how CO2 accumulation affects weather and adds weight to our conclusion that continued accumulatio of CO2 will cause harm that can be reduced if future emissions are reduced.”

Image prompt: create an image with multiple panels showing wildfires, floods, drought with question marks sprinkled in the individual panels.

[Standard bleg:  Although my style is know-it-all-ism, I do sometime entertain the thought that, here and there, I might be mistaken on some minor detail.  I would welcome comments on these views.]

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[1] And the difficulty of answering it yes or no has nothing to do with Schrodinger’s poor cat.