> you can't just say "complex interaction" and still call this a consequence of climate change when the causation is absolutely unclear beyond "less water = warm = bad".

I went out of my way - several times - to mention I was not presenting an opinion on the actual cause here. I don't know if global warming caused this. Hopefully the third time will be the charm.

I was arguing that the dismissal of global warming being a possible cause on the basis of it changing too fast was unreasonable.

> The grandparent explicitly asked whether climate change is the reason in this specific instance

No, they very specifically said they found it hard to believe climate change could be a cause because just a year or two ago it wasn't a problem. They did not ask if climate change could be a reason, but said that due to the timing they thought it made climate change significantly unlikely to be a possible cause.

> It might possibly be, yes, but the fact that 2019 had a lot of water (when climate change was arguably worse since there was no dent in emissions by lockdowns) needs some explanation.

In fact, you continued with the same mistake they made, so I apparently did not make a clear argument the first time. Hopefully I can rectify that.

Let's start with a much simpler example. A bowl of ice sitting out at room temperature. Now graph the temperature over time. You'll see it rise for a bit, then stop at 0 C for a fair while, and then start to rise again.

You can't look at just the temperature to determine the total energy the bowl is gaining. Just because the temperature rise stopped at 0 C doesn't mean the temperature won't continue to rise in the future. The fact the temperature stopped at 0 C is just a result of the physical nature of the system. Similarly, the nature of the ice changes suddenly. It's solid until it's not.

These effects aren't nice and linear, or even particularly smooth. You can't just take two arbitrary points in time and come to any great conclusions about the system.

It's also important to realize that this is a single very simple hypothetical. In reality there are many changes that weren't relevant due to the simplicity. Take the change from solid to liquid. In a bowl, not a big deal. But what if it's a permanent glacier on a mountain? As ice it'll basically sit there. As water, it leaves. Now the mountain is in a very different state, and won't behave the same as it did in the past. The area around the mountain also gained a bunch of water, which will change the systems there too, and then that just spirals outward. Classic butterfly situation, except instead of a butterfly flapping it's wings we just melted and moved however many millions or billions of metric tons of water.

And water can get involved in all sorts of fun stuff. Ice looks positively boring in comparison.

There's a reason I can't find a better way to sum this up than "complex interaction." I agree that's not a reason to blame climate change for anything in particular, but it's absolutely a good reason not to dismiss it as a possible cause out of hand just because some simple correlation didn't happen the way you thought.

It's not simple, so you can't expect it to behave simply. Coming up with a simple correlation and demanding it be true is just not reasonable.

> (when climate change was arguably worse since there was no dent in emissions by lockdowns)

This is just not true. Emissions are not directly causing heating, but causing more heat from the sun to be trapped. Think of it like putting on blankets. If you've thrown on three blankets already and then take a few minutes to decide to grab a fourth, you aren't suddenly colder. You're still just as warm as before, and warming up just as fast. You're just slightly cooler than you'd be if you'd grabbed the fourth blanket faster.

So even if there was a simple and direct relationship between temperature and river level, you really would not expect any kind of year-to-year response to emissions levels. No explanations are required.

> And if your observation doesn't match your thesis, simply saying "complex interaction" is not sufficient

I hope by now what I was trying to say is clear. You can't assume your thesis is correct, even if it seems nice and simple. It's not a safe assumption when you're dealing with such a complex and chaotic system.

We don't know what kind of variable the water level is, or how to expect it to behave. Does it have jumps and halts in it, like the temperature of water/ice? Is there some threshold effect and it'll appear to just suddenly change nature like ice turning to water?

And something like the water level of a river is not going to be as simple as an ice cube melting. It's going to be a combination of other systems that also influence each other. But the root causes - if you trace them back far enough - will be things like how ice melts. So you expect to - and do - see effects like you see there. Sometimes things don't change much until they change suddenly. Sometimes something seems to stop changing, even though the cause of the change is still happening.

But without knowing those details, what kind of thesis can you come up with that even has a shot of being halfway decent?

You can't. That's my point. The thesis is no good, and shouldn't be used. The thesis is assuming the ice changes temperature smoothly, and is doing so a hundred or thousand times over. It's so oversimplified that it has no power. When the observation doesn't match expectations, it tells you nothing. There was never a good reason to expect the observation to match in the first place.