The Guardian has a quote from Professor Stephen Sherwood of the University of New South Wales, in which he takes a pot shot at the Lewis Crok report.
The report is standard cherry-picking. It offers no new evidence not already considered by the IPCC, relying very heavily on a few strands of evidence that seem to point toward lower sensitivity while ignoring all the evidence pointing to higher sensitivity.
It relies heavily on the estimate by Forster and Gregory, which was an interesting effort but whose methodology has been shown not to work; this study did not cause the IPCC to conclude that sensitivity had to be low, even though both Forster and Gregory were IPCC lead authors and were obviously aware of their own paper.
This demonstrates conclusively that Sherwood hasn't read the Lewis/Crok report, the whole point of which is that, once you have discarded all the lines of evidence that AR5 itself says are unreliable you are left with only the GCMs and the energy budget studies. Here's Lewis and Crok in their own words:
...we will accept the conclusion in AR5 that estimates of ECS based on:
- past climate states very different from today
- timescales different than those relevant for climate stabilization (e.g. climate response to volcanic eruptions)
- forcings other than greenhouses gases (e.g. volcanic eruptions or solar forcing)
may differ from the climate sensitivity based on the climate feedbacks of the Earth system today. Accordingly, so far as observational estimates of ECS are concerned, we concur with the AR5 authors that reliance should primarily be placed on instrumental estimates based on warming during a substantial part or all of the period since 1850.
The Forster and Gregory study is based on satellite observations at the top of the atmosphere, and is therefore not "based on warming during a substantial part...of the period since 1850". Lewis and Crok discuss it in their section on the Fourth Assessment and in particular the way the IPCC fiddled the figures in AR4, but is only mentioned in passing thereafter.
Far from relying heavily on it, as Sherwood falsely states, Lewis and Crok explicitly agree with the IPCC that it should not be relied upon.