Anthony Watts has a "guest essay" by Pat'n Chip (archived here, latest update here), the duo from the CATO Institute. (Part of their job seems to be to spread disinformation about climate science. It's a good lark. Money for jam. They don't have to do much except spend a few minutes every now and then writing stuff and nonsense.)
Today's serving has a woody flavour. They are claiming that a new paper in GRL, by Martin Tingley and colleagues, contradicts a paper by Michael Mann. Michael Mann says, no. That's wrong.
To summarise
As suggested by Steve Bloom in the comments, here are the main points as I see them:
- Tree ring growth reconstructions do not register the sudden (short-lived) drop in temperature following very large volcanic eruptions of the past millennia. This has implications for estimates of climate sensitivity based on paleoclimatology. (Mann12)
- Latewood density measures exaggerate the drop in temperature following large-ish recent volcanic eruptions, Krakatau and Novarupta. (Tingley14)
- The new paper by Martin Tingley et al complements, rather than contradicts, the 2012 paper by Mann et al.
- In dendrochronology, density is not the same as tree ring growth and one does not necessarily follow the same pattern as the other.
Initial impressions
Before I discovered Michael Mann's Huff Post article, I looked at the Mann paper and the abstract of the Tingley paper and at first glance it looked to me as if the papers were about different things. Or at least about different volcanic eruptions. I had some questions, though, because both papers were looking at how the sign of a temperature drop after large volcanic eruptions are manifested in tree rings.
So I went to the Tingley paper itself. It's not open access, so unless you can get hold of a copy, you'll have to take what I write at face value. Or you can read what Michael Mann has written about this at Huffington Post.
