In popular press, I frequently read claims according to which climate change not only leads to increased average temperatures but also claims that it leads to more extreme temperatures. Those claims are however usually not made in a formal mathematical way.
Have people made those claims in a formal way that holds up to scrutiny? I could imagine measures such as entropy to measure how extreme weather happens to be. Is the entropy of our weather going up as a result of climate change or are there other metrics that point to increased extreme temperatures?
It doesn’t make sense to ask for a “formal argument” about something like that. You can’t write a closed form equation for a system that big, with that many things going on. Any “pure logic” argument you use can’t be validated; you have no way to know you’ve taken everything into account. Trying to do that sort of thing is what got Aristotle into trouble.
There are large simulation models that act a lot like the climate. They are of course validated against the actual climate, and have been improving. If you introduce more heat into those models, you get more extreme weather. Actually the real climate seems to be more sensitive to change than the models, probably because people were “conservatively” tuning the models to always act like the observed climate regardless of “minor” perturbations.
I don’t think simulation is “formal”. I do think it’s pretty convincing.
I am not sure that’s a well-formed question. Chaos and extreme excursions aren’t really entropy. But throwing in a lot of heat definitely increases the number of accessible states...
Aren’t the actual measured extreme temperatures a “metric of extreme temperatures”? What more do you want, exactly?
Also, why are you asking about this on Less Wrong rather than someplace where there are actual experts?
Do you have a recommendation for a venue where to ask the question?
That said, I do expect LessWrong to be a place where there are people who thought critically about claims and while climate change isn’t widely seen as an existential risk in this community we do have enough people who think it matters enough to have a clear view of the state of the evidence.
I don’t see why rigorous simulations shouldn’t be seen as leading to formal knowledge.
There are various metrics for entropy and how those changes for temperature is a well formed question. Whether or not it’s what people mean when they say that the weather is getting more chaotic is a separate question.
If it’s not what they mean the question is whether there’s another metric for chaotic that gives the answer that the weather is getting more chaotic.
I don’t know, because I’ve never wanted to ask that kind of question. To be honest, I’d try Reddit. But you have to be able to assess the signs of clue factor in the particular forum you use.
Actually, it occurs to me that if I personally were going to look into this in more depth, I’d go back to the latest IPCC report, refresh myself on what’s in there, and then start following references from that. That avoids having to evaluate expertise in random forums, and is probably a faster way to get more comprehensive answers anyway.
It has been a while since I read the IPCC report but from what I remember it did not make an attempt to use a metric such as entropy to quantify that the weather gets more irregular. That however does not mean that there’s nobody who calculates such metrics.
I think the analysis basically derives from modeling weather as something like a normal distribution around a mean (climate). If the mean of the distribution increases, the probability mass on a fixed region above the mean increases, often dramatically. See this post for a deeper dive on this phenomenon: https://putanumonit.com/2015/11/10/003-soccer1/
I don’t think anyone is arguing that the variance of temperatures is increasing, or at least that’s not what people usually mean. There are second order effects with things like shifting El Niño, but no one I’ve heard thinks they’re going to make rare cold weather events more likely to a dangerous extent.