Thread by @AndrewDessler

I see a lot of people with Twitter climate Ph.D.’s saying that “there’s no evidence that extreme weather is getting more severe.” This is wrong.

THREAD. 1/

Summary:
1. Extreme temperatures are getting more severe
2. Extreme rain events are getting more severe
3. Sea level is rising, leading to bigger extreme sea level events
4. Oceans are acidifying
These are 100% certain and virtually certain to be connected to human activities. 2/

First, realize that, if climate is changing, then *by definition* the weather must be changing. 3/

https://twitter.com/AndrewDessler/status/1109187916734103553?s=20

There is a huge amount of data showing that temperature extremes are getting more worse. This is one of the first articles I saw on this and it’s still one of my favorites (by @SISeneviratne) 4/

nature.com/articles/nclim…

There have been lots of attribution studies that show that these events are linked to human-induced climate change. This is just one study, but there are tons more if you know how to use google scholar: pnas.org/content/114/19… 5/

There is also a huge amount of data that rainfall extremes are getting more extreme. See this tweet thread for data & for explanation of why it’s us that’s doin’ it. 6/

https://twitter.com/Knutti_ETH/status/1128559261288738816?s=20

Sea level is going up as a direct consequence of warming temperatures (which are due to humans). Increases in sea level make extreme sea level events (e.g., storm surge) more extreme. 7/

sealevel.colorado.edu

We also are 100% sure the pH of the oceans is going down (“acidifying”). We have 100% confidence that this is due to human CO2 emissions. 8/

Then there are the things that we’re not quite 100% sure about — e.g., droughts and floods. Droughts and floods are much more complex than simple trends in temperature. Floods, for example, depend on infrastructure as much as they do on intensity and duration of rainfall. 9/

The same change in rainfall can cause floods in one location, but not in another, depending on how rich the region is and how much they’ve spent to avoid floods. So the existence or lack of a trend is more difficult to interpret than a trend in temperature.
10/

Let’s talk about hurricanes. We don’t have very good measurements of hurricanes, so it’s hard to confidently estimate trends from data (e.g., the Atlantic is the only basin where we routinely fly planes into the storms and they’re only about 12% of global TCs). 11/

There is some evidence that they’re getting more intense (e.g., myweb.fsu.edu/jelsner/strong…). However, the reason scientists are so confident that hurricanes are getting more intense is because of a little thing called physics. 12/

We can make a strong argument about the controlling factors on hurricane intensity and those suggest stronger hurricanes as the climate warms. This leads us to a reasonable level of confidence that hurricanes will indeed get stronger. 13/

https://twitter.com/AndrewDessler/status/1177062650448162817?s=20

Ditto for hurricane rainfall. 14/

https://twitter.com/AndrewDessler/status/1177062655078608896?s=20

For more about hurricanes, read @profadamsobel's great congressional testimony. 15/

https://twitter.com/profadamsobel/status/1177289856768270338?s=20

So, yeah, the science is clear: extreme weather is getting more extreme — and it’s us doing it. 16/