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Do climate models predict extreme weather?

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31–40 of 223 posts

Re: Do climate models predict extreme weather?

#31
post #14
post #10

Models say only what the modeler tells them to say.

That's not true. Climate models model and simulate physical and chemical condition on Earth. Modellers don't know what they say beforehand. Offhandedly portraying scientists and researchers as dishonest and conspirators in every opportunity possible seems the default here.

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?

Re: Do climate models predict extreme weather?

#32
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…

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Re: Do climate models predict extreme weather?

#33

I believe in climate change, but if you look into how the climate change computer models are written, it really makes me feel like it is contrived. Here's the problem with climate change modeling, you are modeling a complex chaotic system, you just cannot do it accurately. You have to be honest about it.

>Here's the problem with climate change modeling, you are modeling a complex chaotic system, you just cannot do it accurately Its more than that. Large models have hundreds of adjustable parameters, which each may be tweaked within reasonable ranges to simultaneously backfit historic data and potentially get any kind of future result. It's very easy to get biased outputs which look totally reasonable, which is especi…

The orthodoxy's stance has been to make the most mild predictions possible for decades. And now, we're seeing worse-than-predicted extreme weather events. Go figure.

Re: Do climate models predict extreme weather?

#34

I believe in climate change, but if you look into how the climate change computer models are written, it really makes me feel like it is contrived. Here's the problem with climate change modeling, you are modeling a complex chaotic system, you just cannot do it accurately. You have to be honest about it.

> you are modeling a complex chaotic system, you just cannot do it accurately

You can't really model anything "accurately", but you can assign a subjective (probability is subjective) probability to certain outcomes based off an analysis of your model, and what in your best judgement are the correct parameters.

This is why the papers containing uncertainty analysis of varying quality, the press releases will have some handwaving, and the articles in the newspapers will contain nothing of the sort.

Re: Do climate models predict extreme weather?

#35

I believe in climate change, but if you look into how the climate change computer models are written, it really makes me feel like it is contrived. Here's the problem with climate change modeling, you are modeling a complex chaotic system, you just cannot do it accurately. You have to be honest about it.

[deleted]

Re: Do climate models predict extreme weather?

#36
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…

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…

Absolutely agree with all this. I'd also want to add that another thing to think about is not just how unlikely any particular event is, but the probability of multiple unlikely events occurring across the globe in a relatively short time. After all, Earth is big enough that rare events will happen somewhere. Unusual weather patterns in multiple locations start to point to a systematic cause.

Re: Do climate models predict extreme weather?

#37

I believe in climate change, but if you look into how the climate change computer models are written, it really makes me feel like it is contrived. Here's the problem with climate change modeling, you are modeling a complex chaotic system, you just cannot do it accurately. You have to be honest about it.

It’s complex and chaotic, sure. But as you increase time horizons, and area of simulation larger and larger, that complexity and chaos starts to average out. So you can’t take a singular datapoint from a climate model, and make any concrete statements, but you can take thousands to millions of them and start making probabilistic statements. Additionally it’s not like these models are untested. Their predictions are c…

Generally the defining feature of non linear mechanisms is that the long term behaviour is non-intuitive. I'd expect that to include not having a predictable mean

Re: Do climate models predict extreme weather?

#38

I don't really understand the conflict that seems to exist between the title of the article ("Do Climate Models predict Extreme Weather? ") and the body of the article, which argues that event attribution can't be done with much accuracy. So ... "Do Climate Models predict Extreme Weather? ": yes, yes they do. But .... "how much impact does climate change have on extreme weather?": hard to say with much accuracy, but…

Sabine plays a mean game when it comes to marketing her work, i.e. slightly reductive titles and a vaguely countercultural spin in her prose.

Re: Do climate models predict extreme weather?

#39

Earlier quoted context omitted.

It’s complex and chaotic, sure. But as you increase time horizons, and area of simulation larger and larger, that complexity and chaos starts to average out. So you can’t take a singular datapoint from a climate model, and make any concrete statements, but you can take thousands to millions of them and start making probabilistic statements. Additionally it’s not like these models are untested. Their predictions are c…

Can you give me another example of a chaotic system that can be correctly forecasted years out?

Sure. Pick a spot offshore and measure the water depth, to the centimeter. Moment to moment, the precise value varies chaotically due to countless transient phenomena, from the direction and strength of the wind to the heading of the last boat to come anywhere near it. However the tides can be forecast years out.

Just because weather is chaotic and unpredictable doesn't mean that climate is.

Re: Do climate models predict extreme weather?

#40
I believe the climate it changing. I believe human activity has contributed to these changes. However, I do not believe _every_ "extreme event" belongs in that category.

For example, the recent fires in the Denver / Boulder. Have you been there? It's effectively a desert. Dry, very dry. Open. There are few natural barriers once a fire starts. Based on what I know of the area, those homes - God bless those families - were built in harm's way. That disaster - regardless of climate change - was inevitable. To suggest otherwise is simply irresponsible.

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