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Do climate models predict extreme weather?

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Re: Do climate models predict extreme weather?

#41

Post by vkou »

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…

This year, the pacific north west got hit with the four Fs. Fires, floods, and fucking freezing weather.

In the summer, we had an unprecedented heat wave which killed thousands of people. Seattle hit 108°F/42°C. The town of Lytton, BC, hit 118°F/48°C[0], and then completely burnt down in a 30 minute firestorm. More rain would have been great.

We didn't get it.

We got it in the winter, and it was absolutely devastating. [1] To cap the year off, we ended with a record-setting freeze (With, thankfully, comparatively moderate snowfalls).

So, yes, more rain, less rain, more heat, less heat, we got all that. Unfortunately, weather is not a bank account, and having your town burn down to the ground in the summer, followed by a flood in the winter doesn't tend to cancel things out.

[0] An all-time heat record for Canada.

[1] https://en.wikipedia.org/wiki/November_2021_Pacific_Northwes...

Re: Do climate models predict extreme weather?

#42

Post by SV_BubbleTime »

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…

> No one is going to bother doing an attribution study to say, "Climate change is 20% responsible for the fact that we didn't have a fire this year."

Well, I mean you would hope so since that would be honest science.

Re: Do climate models predict extreme weather?

#43

Post by godelski »

divbzero wrote: post #8
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 can occur in both directions. A year with more rain may be less prone to fire but more prone to flooding. It also does not take natural disaster to notice extremes. People who have lived in the same area awhile will know if there is an unusually wet, dry, hot, or cold year.

Actually it even gets more complicated. California is a good example. Dry weather makes more fires yes. More fires means less vegetation with deep roots. Not only do these shrubs burn more easily, but they neither hold back water. This makes heavy rainfall more dangerous as flash floods become more common. It's crazy how interconnected these things are and frustrating because it becomes difficult to talk about. The whole picture is so complicated but focusing on a small aspect over simplifies the problem too much.

Re: Do climate models predict extreme weather?

#44

Post by dragonwriter »

chiefalchemist wrote: post #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 -…

> For example, the recent fires in the Denver / Boulder. Have you been there? It's effectively a desert. Dry, very dry.

Not normally, so much, but yes, when the entire state ranges between “abnormally dry” and “extreme drought” [0], it probably seems desert-like.

But...how are those unusual and extreme conditions an argument against the events being a product of anthropogenic climate change?

[0] https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonito...

Re: Do climate models predict extreme weather?

#45

Post by dpierce9 »

contravariant wrote: post #25
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…

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…

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

Re: Do climate models predict extreme weather?

#46

Post by hpcjoe »

fasteddie31003 wrote: post #28
avianlyric wrote: post #26

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?

Planetary orbits. Stability is important there. But 3 and greater body problem in Newtonian mechanics is inherently chaotic. Add in spin-orbit coupling, relativity and other effects, and its a real mess, with no exact closed form solutions.

That said, we can predict, with some level of accuracy the stability of of orbits in a number of cases. Approximate solutions can be managed with various levels of theory, perturbations, and numerical simulation.

Re: Do climate models predict extreme weather?

#47

Post by Breazy »

godelski wrote: post #43
divbzero wrote: post #8

Earlier quoted context omitted.

Extreme weather can occur in both directions. A year with more rain may be less prone to fire but more prone to flooding. It also does not take natural disaster to notice extremes. People who have lived in the same area awhile will know if there is an unusually wet, dry, hot, or cold year.

Actually it even gets more complicated. California is a good example. Dry weather makes more fires yes. More fires means less vegetation with deep roots. Not only do these shrubs burn more easily, but they neither hold back water. This makes heavy rainfall more dangerous as flash floods become more common. It's crazy how interconnected these things are and frustrating because it becomes difficult to talk about. The w…

The wetter weather enjoyed by the past few generations of Californians was an aberration. California is usually even dryer than it is presently.

> Paleoclimatological studies indicate that the last 150 years of California's history have been unusually wet compared to the previous 2000 years. Tree stumps found at the bottom of lakes and rivers in California indicate that many water features dried up during historical dry periods, allowing trees to grow there while the water was absent. These dry periods were associated with warm periods in Earth's history. During the Medieval Warm Period, there were at least two century-long megadroughts with only 60-70% of modern precipitation levels. Paleoclimatologists believe that higher temperatures due to global warming may cause California to enter another dry period, with significantly lower precipitation and snowpack levels than observed over the last 150 years.[7]

https://en.wikipedia.org/wiki/Climate_change_in_California#P...

Re: Do climate models predict extreme weather?

#48

Post by ruined »

timmg wrote: post #15
divbzero wrote: post #8

Earlier quoted context omitted.

Extreme weather can occur in both directions. A year with more rain may be less prone to fire but more prone to flooding. It also does not take natural disaster to notice extremes. People who have lived in the same area awhile will know if there is an unusually wet, dry, hot, or cold year.

> Extreme weather can occur in both directions. Of course that's true. What I guess I was trying to say is that a change in climate doesn't necessarily mean more extreme weather (in every instance, I mean). A change in climate could cause something to happen more or happen less . But no one is going to study a given year and a given place that doesn't have an extreme weather event.

one thing to note is that, generally, any comparatively calmer system with fewer extreme events is in a lower energy state. and that is exactly what we are moving away from.

Re: Do climate models predict extreme weather?

#49

Post by fubarr »

Climate is a ~30yr moving average of weather. Climate models cannot attempt to model weather events. Such events can rarely be predicted more than a week or two out. The above should tell you that using a climate model to predict anything about weather events is a pointless exercise. Particularly trying to derive the statistics of weather events. The stats are built in to the models!

Re: Do climate models predict extreme weather?

#50

Post by dnautics »

It bothers me that the A/B in these models is between "pre-industrial" and now, seems like a better comparison over the timescales people are expecting to match up with their "perceived experiences of increased climate disasters" should be "20 years ago vs now" e.g.
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