Michael Mann, a man who never saw a fray he didn't want to enter, has decided to enter the climate sensitivity fray, with an article published simultaneously in the Huffington Post and Scientific American. Some of it is a bit odd to tell the truth.
For example, take this bit about the IPCC's decision to reduce the lower bound on its estimate of climate sensitivity down to 1.5°C.
The IPCC had lowered the bottom end of the range, down from the two degrees C it had set in its Fourth Assessment Report, issued in 2007. The IPCC based the lowered bound on one narrow line of evidence: the slowing of surface warming during the past decade—yes, the faux pause.
However, those who have read the relevant parts of the Fifth Assessment and indeed those who are familiar with the recent Lewis/Crok report on climate sensitivity will be aware that the IPCC actually gave a completely different explanation for their decision to reduce the lower bound.
The lower temperature limit of the assessed likely range is thus less than the 2°C in the AR4, but the upper limit is the same. This assessment reflects improved understanding, the extended temperature record in the atmosphere and ocean, and new estimates of radiative forcing.
I don't know about you, but I count that as three lines of evidence not one.