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Do climate models predict extreme weather?

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Re: Do climate models predict extreme weather?

#71

Post by viraptor »

fubarr wrote: post #49

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!

This can be easily shown to be false. I can't tell you if it's going to rain next week in most cases, but I can easily tell you about how many days in a year it's going to rain over a large area. Same applies to how many floods we're going to have and bushfires. We've been doing that for a very long time now.

Re: Do climate models predict extreme weather?

#72

Post by [deleted] »

vkou wrote: post #41
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 devastati…

[deleted]

Re: Do climate models predict extreme weather?

#73

Post by sanxiyn »

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…

I think you are the problem. Don't lie. Ever.

Re: Do climate models predict extreme weather?

#74

Post by geraneum »

fasteddie31003 wrote: post #7

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.

The tricky part of this argument is the use of the word "accurate". Since you are talking about a statistical model, it's worth keeping in mind that this word has a mathematical definition in that context. The output of the said models have an accuracy attribute presented for them. It's not a binary value of accurate/not-accurate, and what matters is how accurate and about what specific prediction. You can argue that the modeling process for designing the breaks of your car is also not 100% accurate, and it really doesn't need to be! It needs to be accurate enough about the break's relevant properties (stopping power, wear and tear, performance in wet wheather, etc.) This is not a scientific analogy to climate forecasting, I just used it to explain the core idea in more familiar terms.

The issue is that it's hard to get these across correctly to the general audience. It requires analytical thinking and patience and attention to details, which none are compatible with how today's media and social networks are incentivized and structured (short, catchy, flashy, clickbaity, infuriating, etc.)

Re: Do climate models predict extreme weather?

#75

Post by contravariant »

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…

That's fair but the problem with such a deliberate lie is that I must view everything with suspicion when people say something that supports climate change. Pretty much the only way I can know something is mostly accurate is when there's a shiny leaflet in front of it 'for educators' that I can ignore.

And it's not just this problem, it's all problems where people need to be convinced 'for the greater good'. I truly worry that the rightful distrust that those 'white lies' are causing is doing irreparable harm. It's also quite fragile since it opens room for people to point out the misleading or even false information, and in those cases people have a nasty tendency to assume the opposite must therefore be true.

Re: Do climate models predict extreme weather?

#76

Post by hammock »

dTal wrote: post #39
fasteddie31003 wrote: post #28

Earlier quoted context omitted.

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.

>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.

That's a good analogy of my skepticism for AGW. We are saying temps went up 1c over 100 years, taking daily measurements, and comparing them to ice cores which are our measurements of historic temps... Only those ice cores aren't daily- they're thousands of years apart. So the ice cores data is irreparably smoothed in a way the recent data is not.

Re: Do climate models predict extreme weather?

#77

Post by xyzzyz »

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…

Ah, scientists lying for the benefit of stupid masses. Worked great for public health experts over past 2 years, I'm sure it'll work great for climatologists too.

Re: Do climate models predict extreme weather?

#78

Post by prawn »

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.

Might be wrong, but I think unseasonably wet weather can also increase the fuel load for a fire. i.e., boisterous undergrowth due to wet weather during Spring, which then dries out and is available for fire season.

Re: Do climate models predict extreme weather?

#79

Post by dr_zoidberg »

contravariant wrote: post #75
labster wrote: post #61

Earlier quoted context omitted.

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…

That's fair but the problem with such a deliberate lie is that I must view everything with suspicion when people say something that supports climate change. Pretty much the only way I can know something is mostly accurate is when there's a shiny leaflet in front of it 'for educators' that I can ignore. And it's not just this problem, it's all problems where people need to be convinced 'for the greater good'. I truly…

I think part of the problem is that the discussion has already been rigged beforehand, and now you _must_ lie to be heard. Not because you want to, but because those that came efore you did. So if you now simply state the facts as they are, the other side will go "oh, things are actually better then, because the previous experts were pretty alarmist, and now this person is telling me something that sounds normal an reasonable".

You know where else I see this pattern? Digital forensics, my area of work. People have been selling snake oil all around for years, and know lawyers, attorneys and judges (in general, with some god particular exceptions) believe in whatever they've been seeing in CSI, or their "IT guy" convinced them as possible. Who cares that I'm one renowned expert in the field? _Their guy_ said this thing was possible, so I must be lying!

Re: Do climate models predict extreme weather?

#80

Post by lisper »

It's not just the frequency of extreme events that is going up, but the intensity of the most extreme events. That is a function of the shape of the tail of the distribution. A very small change in the mean or median, or even just the standard deviation, can result in a huge increase in the expected value of the extremes.

Combine this with human psychology and you have a recipe for catastrophe -- literally. You get an extreme event, and then everything reverts to the mean and things seem normal for a while, and people assume that the extreme event was a fluke. It wasn't. It's the new normal, and the next extreme event will be even worse.

You see this playing out in California right now. Everyone thinks the drought is over because it rained last month. It's not over. It's just getting started.

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