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Do climate models predict extreme weather?

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Re: Do climate models predict extreme weather?

#91

Post by d--b »

The point is that warning about extreme weather events is the only narrative that got people to consider global warming a problem at all.

A 2 degree change in average temperature doesn’t change how people live. A heat wave does.

Now I don’t know if it’s actually true or not but it feels like the frequency of extreme weather event has increased. It’s difficult to say because that’s something our grandparents already said 50 years ago.

But then there are 2 possibilities:

1. Either the frequency of extreme events has actually increased and it would be hard not to pin it down on climate change (despite our inability to do it scientifically).

2. Or it hasn’t changed significantly (statistically speaking), and it’s all a bit of mass hysteria.

Either way doesn’t actually matter. I personally don’t care if people are scared about the acidification of oceans or about rain for their next barbecue. As long as they vote for people who want to do something about it.

I personally have been criticized by friends for saying that we don’t know what the impact of climate change is on the weather. I don’t care anymore. It’s all about narrative. That one works, let’s not poke holes in it. It only benefits people running polluting industries.

Re: Do climate models predict extreme weather?

#92

Post by mbfg »

My understanding from the video is:

the climate models stink, and everyone in the science understands this but has difficulty communicating this.

The real world is more extreme than the models. But we have no way to extend the models to cover the seen extremes, nor do we know how to cap the possible extremities in any model.

Do i have that right?

Re: Do climate models predict extreme weather?

#93

Post by sanxiyn »

magicalhippo wrote: post #67
refurb wrote: post #31

Earlier quoted context omitted.

Models are constantly tweaked to make them more accurate. How do you do that without looking at output and then going back to tweak it?

One way is to verify them. Run multiple variations on data from the 1950's and see how they compare to measured values up to today. Throw away the models that don't fit the measured values. Then you have some confidence that the remaining variations may be representative when run into the future. This is also done in weather forecasting, though maybe they run the model in reverse, I can't recall. Same idea though, ve…

Yes this happens, but it is very controversial. To quote from the article I linked above:

> The question of whether the twentieth-century warming should be considered a target of model development or an emergent property is polarizing the climate modeling community, with 35% of modelers stating that twentieth-century warming was rated very important to decisive, whereas 30% would not consider it at all during development. Some view the temperature record as an independent evaluation dataset not to be used, while others view it as a valuable observational constraint on the model development. Likewise, opinions diverge as to which measures, either forcing or ECS, are legitimate means for improving the model match to observed warming. The question of developing toward the twentieth-century warming therefore is an area of vigorous debate within the community.

Re: Do climate models predict extreme weather?

#94

Post by pmjones »

WoahNoun wrote: post #21
pmjones wrote: post #10

Models say only what the modeler tells them to say.

Do you have any evidence for this? Are you implying that climate change isn't happening?

> Do you have any evidence for this?

It's the very definition of how computer models work. The modeler writes the program, determines all the inputs, determines how the logic of the program will respond to the inputs, etc. The modeler is in complete control of the model, tells it how to behave, and thus the model says only what the modeler tells it to.

> Are you implying that climate change isn't happening?

Non sequitur.

Re: Do climate models predict extreme weather?

#95

Post by throwawaylinux »

labster wrote: post #61
contravariant wrote: post #25

Earlier quoted context omitted.

That's why in these discussions it's usually better to talk about specific statistics like 'the chance of a wildfire has gone up by 20%', or perhaps more clearly 'the average time between extreme floods has gone down from once every 100 years to once every 60' (which I find communicates the point a bit more clearly). That said personally I think that should be as far as the discussion goes, talking about a specific e…

As a climatologist by education and a dabbler in politics, I think you are radically misjudging the ability of most people to have rational discussions about unwelcome statistics. If you say severe weather will increase by 20% due to climate change, people will hear that there’s an 80% chance weather will stay the same. And they say I’m just being alarmist. When I say that this storm may have been enhanced by climate…

> Most of the world is not HN, where nuanced discussions work. Most of the world does not give a shit about climate change unless they will personally suffer in some way. So I lie. So that even if this storm or that hurricane didn’t hurt them, they will have empathy for those who did suffer from a climate-enhanced storm. Because if we wait for everyone to feel the impact in earnest, it will be far too late.

This is fascinating. I would normally have written this off as a troll like a climate denier trying to discredit one side, but you seem to be well established here and quite possibly identifiable from your about page (not that I tried or am interested in trying to troll through it, just had a quick glance).

Don't get me wrong I absolutely accept that some scientists may take a bit of license with the truth when they say a particular weather event was caused or made more likely by climate change without having gone through a full analysis of that particular event and situation. And I even accept there is corruption and dishonesty all the way from a bit of unconscious bias to much worse.

It's quite amazing to see a scientist out and admit they lie about the science in order to try to influence public opinion in the hope of effecting the social or political change they want. I really admire and appreciate your honesty here, if nothing else. Can I ask whether you act in any professional or academic capacity as a climatologist? And what are the nature of the lies? Who are they to, how are they communicated?

Re: Do climate models predict extreme weather?

#96

Post by dpierce9 »

contravariant wrote: post #82
dpierce9 wrote: post #45

Earlier quoted context omitted.

Replace ‘extreme weather’ with ‘lung cancer’ and ‘climate change’ with ‘smoking’ to see the soundness of this reasoning.

No I stand by it, talking about cause when the effect is probabilistic is an endless quagmire that people should avoid. Trying to attribute an individual case of cancer to smoking is nigh impossible, which is part of the reason tobacco companies got away with it for so long. Plenty of companies have gotten away with bad practices by simply demanding proof for each individual case, the earlier we recognize this as a m…

Smoking causes cancer is true. But not everyone who smokes will get cancer and some people who don’t smoke will get cancer. Causation is hard. But we also know that particular cancers are caused by particular acts of smoking. The causal generalization is built on the observation of particulars. It might be hard but I don’t see why we wouldn’t, a priori, be able to say ‘this event was made worse by climate change because it likely affected input x’.

I generally agree with you that this isn’t easy to do, the value isn’t clear, and whether we can say such things with the evidence we have for any particular event isn’t obvious.

Re: Do climate models predict extreme weather?

#97

Post by Breazy »

enkid wrote: post #89
whiddershins wrote: post #86

Earlier quoted context omitted.

In my view, the problem with the noble lie, which you are engaging in, is that it has been an unmitigated disaster with regards to Covid messaging. As it became obvious some officials were willing to lie, this opened the door to many people having no idea who to trust. I believe public trust in leaders and institutions is at an incredible low, and I’m not sure how it can be repaired. Regardless of whether you think p…

Can you give a specific example of what you are talking about? What noble lies were being told about COVID? I heard a lot of "we don't knows, but here is the best bet" which were not lies, but all of the lies I heard absolutely were not noble in that they were not for the public's best interest, but rather for the best interest of the individual saying them.

"Stop wearing masks, they don't work."

Re: Do climate models predict extreme weather?

#98

Post by photochemsyn »

timmg wrote: post #5

One of the things about "extreme weather attribution" that makes me uncomfortable is the asymmetry of it. To be clear: I'm in no way an expert (or even educated) in the area. To give an example. Let's say there's a 1% chance every year that there will be a catastrophic wildfire in some particular area. Now let's say climate change increases a chance of drought in that area. Then we get a wildfire one year and the att…

Extreme weather generally involves intersecting weather systems. For example, 'The Perfect Storm' of movie fame was the intersection of the remnants of a hurricane coming up from Gulf of Mexico with a polar cold front coming across Canada and as I recall a low pressure system out around Nova Scotia. The timing of these events was basically random; if the events had been staggered a few days apart instead of hitting at the same time, it wouldn't have been a perfect storm.

So, where models predict an increase in such events comes down to increasing probabilities of the individual events, kind of like throwing the dice twice as often as before, then you're going to get double sixes (i.e. extreme events) more frequently.

As far as the attribution of specific events, well, you can look back in history and say, historically we've had these events every 100 years or so, so we shouldn't expect three such events over a twenty-year period. This is similar to how a casino might suspect a player is using a loaded die.

However, for one specific event, is it possible? Plausibly you can examine the details of a single event and ask, okay, are there physical characteristics here directly related to climate change, in the same way one could examine a die to see if it was really symmetrical or not? One could perhaps use expectation results, i.e. "we expected this kind of extreme weather event to occur with greater frequency outside the regions where they normally take place, according to frequency results in models forced with extra CO2" etc.

Really though, it's when you get 500-year floods every 5-10 years in Europe, then you know you're 'testing the historical limits'.

Re: Do climate models predict extreme weather?

#99

Post by godelski »

avianlyric wrote: post #68
godelski wrote: post #58

Earlier quoted context omitted.

Non intuitive doesn't mean not predictable. Nor does chaos. Chaos just means that a small perturbation in input parameters can result in a large change in the output. So to have good predictive power you need to pick good inputs with good accuracy. But chaos is also a spectrum so not all chaotic systems are as sensitive as others.

Chaos is also different at different scales. At certain point chaos can be simulated as noise with a known distribution. You can’t make predictions within the noise, but you can describe the shape of the noise and it’s impact on macro scale systems. Perfect example of this is quantum effects. Zoom in far enough and quantum effects make the world entirely unpredictable, and yet I can still accurately predict where I t…

But different noises do different things and have different predictive powers. I think your statements about these systems being impossible to calculate are too strong. We use gaussian noise all the time. In fact there's plenty of machine learning models that use noise and change of variables (we learn the transforms) to represent different distributions. Ones that do actually have good clustering. We can be predictive in these domains. Chaos and randomness don't make inference impossible. This is the 21st century, we're not beholden to Newton nor to deterministic processes.

Re: Do climate models predict extreme weather?

#100

Post by LudwigNagasena »

d--b wrote: post #91

The point is that warning about extreme weather events is the only narrative that got people to consider global warming a problem at all. A 2 degree change in average temperature doesn’t change how people live. A heat wave does. Now I don’t know if it’s actually true or not but it feels like the frequency of extreme weather event has increased. It’s difficult to say because that’s something our grandparents already s…

This attitude exemplifies the problem with the public discourse. The public discourse isn’t about finding out truth and forming actionable democratic consensus, it is about duping “stupid people” into supporting “good things”™.
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