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Comment by btilly | Hacker News Reader

I can only partially agree.

Look at https://twitter.com/CAL_FIRE/status/1298383464094265344/phot... and see how big a chunk 2020 is of all megafires in California history. And 2021 is on track to be even worse.

Past forestry management is why we have the the problem in the first place.

Climate change is why the problem just got so much worse, so quickly. And is why we can't attempt to fix it as gradually as we created it in the first place.

Both are actually important for understanding this subject. And climate change doesn't just come up because it is demanded by pop culture.

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How does that data support the case that climate change is the main culprit? It shows no record fires from ‘77-‘03, and a lot of record fires since ‘03. Why wasn’t there a steady progression, if the cause is slow-and-steady climate change?

It is because natural variation (including a variety of multi-year cycles) far exceeds the long-term warming trend. So global warming shows up as an increased frequency of extreme events when natural variation and warming coincide. But variation is still dominant.

However extreme events become more extreme. We are now seeing extreme events that simply would not have been possible without global warming. For example the 2011–2017 California drought was the most extreme drought in at least 1200 years. And yet, here we are again in what's shaping to be an even more extreme one. And going forward, droughts like this one are going to become common.

> extreme events become more extreme

This is the beef* I had with Cliff Mass when he said the June heat wave in the Pacific Northwest had nothing to do with climate change, it wasn't an extreme event, it was just natural variation. The temperatures may not have been more extreme than known outliers, but what he didn't say is much more important: How often would natural variations lead us to expect events like it and how long would they last?

You can't just say "oh, this is just a typical thing that happens once in a hundred years" when it's happening every year.

* I have lots of other beefs with Cliff, but they aren't relevant to this discussion.

According to a preliminary analysis you can find reported on at https://www.climate.gov/news-features/event-tracker/prelimin..., current models say that the event was a 1/1000 year heatwave with global warming, and a 1/150,000 year event without.

Those numbers are extreme enough to make me question whether the model's tails are heavy enough, but yeah. It basically wouldn't have been possible without global warming.

What happened 1200 years ago that caused a more severe drought? Clearly it wasn’t man-made Climate Change so what was it?

Our reliable reconstruction of the climate record from tree rings ends so we can't say whether there were more severe droughts.

> How does that data support the case that climate change is the main culprit?

Most likely because people don't know what they're talking about. There are a lot of potential causes, probably some more that never come up, but an awful lot of absolutely certain theories.

I can’t really take this seriously when it starts in 1932. Natural disasters didn’t just start happening because humans showed up. Show some data from 200-400 years ago and I’d be more inclined to believe we are living in an outlier.

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