4 ms·

> I can find references in the latest IPCC report to increased frequency of droughts, heavy rain, and heat waves, but I can't find much mention of extreme cold

> I can find references in the latest IPCC report to increased frequency of droughts, heavy rain, and heat waves, but I can't find much mention of extreme cold events I believe my quoted text above states that the frequency and intensity of cold extremes has decreased, as a "virtually certain" fact. > I stand by my main point which was that you _could_ have an increase in both extreme cold events and extreme hot events while the average temperature is increasing, to correct an oversimplification I believe the GP was making. Yes, as a mathematical fact this is undoubtedly true.

theptip 5y ago
I think there is a subtlety in the report there - they seem to use “extremes” to refer to something like the 75th %ile bounds, as in “the edges of the normal range”. Whereas “extreme weather events” is a similar phrase for a different thing, they are more like the 99th %ile outliers. (Made up numbers for discussion, not claiming the actual%, just trying to illustrate a distinction). Note in your quote how they refer to both: > The frequency and intensity of hot extremes (warm days and nights) and the intensity and duration of heatwaves And for cold they say: > while the frequency and intensity of cold extremes have decreased But no mention of extreme weather events like storms. This might sound pedantic but I think it’s two different meanings of “extreme”, they discuss the differences a bit in https://www.ipcc.ch/srocc/chapter/chapter-6/ https://www.ipcc.ch/srocc/chapter/chapter-6/. Anyway, low epistemic confidence on this bit, just my read is a bit less certain on that last point than yours.
- csee 5y ago
  This is a very important point because it's very commonly believed that extreme cold weather (99 pct) will be worsened, and it's central to Scott Alexander's piece. Not storms per se, just the inverse to heat waves. Can anyone find any evidence for this from primary sources like the IPCC? My guess is the answer is that they're going to reduced. If they're virtually certain that 75th percentile events will be reduced that usually suggests that 99th percentile events will be reduced too.

theptip 5y ago

I think there is a subtlety in the report there - they seem to use “extremes” to refer to something like the 75th %ile bounds, as in “the edges of the normal range”. Whereas “extreme weather events” is a similar phrase for a different thing, they are more like the 99th %ile outliers. (Made up numbers for discussion, not claiming the actual%, just trying to illustrate a distinction). Note in your quote how they refer to both: > The frequency and intensity of hot extremes (warm days and nights) and the intensity and duration of heatwaves And for cold they say: > while the frequency and intensity of cold extremes have decreased But no mention of extreme weather events like storms. This might sound pedantic but I think it’s two different meanings of “extreme”, they discuss the differences a bit in https://www.ipcc.ch/srocc/chapter/chapter-6/ https://www.ipcc.ch/srocc/chapter/chapter-6/. Anyway, low epistemic confidence on this bit, just my read is a bit less certain on that last point than yours.

csee 5y ago
This is a very important point because it's very commonly believed that extreme cold weather (99 pct) will be worsened, and it's central to Scott Alexander's piece. Not storms per se, just the inverse to heat waves. Can anyone find any evidence for this from primary sources like the IPCC? My guess is the answer is that they're going to reduced. If they're virtually certain that 75th percentile events will be reduced that usually suggests that 99th percentile events will be reduced too.