New Scientist's Michael le Page is spinning so furiously on the subject of climate sensitivity he looks more like a whirling dervish than a responsible journalist.
Le Page asks whether there is any truth to sceptics' claim that climate scientists now believe that climate sensitivity is lower. He first cites Reto Knutti, as a co-author of the Otto et al paper, saying that climate sensitivity is 1–5°C and most likely 2°C. This is interesting. Let me quote directly from the Otto et al paper:
The most likely value of equilibrium climate sensitivity based on the energy budget of the most recent decade is 2.0 °C, with a 5–95% confidence interval of 1.2–3.9 °C ... compared with the 1970–2009 estimate of 1.9 °C (0.9–5.0 °C...).
So as far as I can see, le Page has taken the the 1970-2009 estimate (rounding up to whole numbers) despite Otto et al arguing this was not their preferred estimate. As Nic Lewis put it in an email to me:
Otto et al argued that the more recent estimate is more reliable, as the average forcing was much higher and the period was unaffected by any major volcanic eruptions. The higher internal variability pertaining to a one rather than four decade period was fully allowed for.
Le Page then goes on to suggest that you can get broader ranges from paleoestimates and climate models. Well yes, I suppose you can, but this is unscientific drivel. Paleoestimates are barely able to constrain the climate sensitivity at all because almost every dataset included in such studies is so shot full of uncertainties. They therefore reflect their priors more than they do the data.
Similarly, we know the climate models are running far too hot. They are on the threshold of falsification already. Why would one possibly want to believe the models?
Le Page is essentially arguing that we should give as much weight to hypotheses and rubbish methods as we should good methods. This is spin, not science.