Bishop Hill More from the empty set
May 6, 2014 Climate: Models Readers may remember the fun we had with a couple of papers at the start of the year. Cai et al found that climate models that simulated extreme rainfall well predicted more frequent El Ninos. Meanwhile Sherwood et al found that climate models that simulated clouds well had high climate sensitivity, a position that I characterised as "the best cloud simulators are the worst temperature simulators". Much amusement ensued when it emerged that the intersection of "best cloud simulators" with "best rainfall simulators" was in fact the empty set.
Leo Hickman now points us to a new paper by Su et al, which examines some climate models and concludes:
New model performance metrics proposed in this work, which emphasize how models reproduce satellite observed spatial variations of zonal-mean cloud fraction and relative humidity associated with the Hadley Circulation, indicate that the models closer to the satellite observations tend to have equilibrium climate sensitivity higher than the multi-model-mean.
This is an admirable confirmation of Sherwood's findings. Like I said: the best cloud simulators are the worst temperature simulators.
Reader Comments (10)
I welcome Mr Hickman's apparent discovery of the merits of satellite measurements (aka real-world experimental data).
Is there any evidence that Leo...erm...understands that the solution isn't to pick the best temp simulator in order to predict the future of temps and the best cloud simulator in order to predict the future of clouds?
Sorry if I'm being thick here but do I understand correctly that this suggests:
- if "better" models = higher sensitivity then modelled temperature projections should be at the higher end of the range
- so other factors (e.g. aerosols?) would need to be increased in order to correctly hindcast historical data and that the recent, so-called "pause" becomes even harder to explain i.e. if the models run even hotter then the counter-balancing factors must be increased to cool them down still further
- that there is little evidence / theoretical justification for ramping up these counter-balancing factors up so they effectively become arbitrary fudge-factors
- which suggests the models are missing some important physical processes and/or impacts of natural variation
Hope I got that right! (assuming climate actually simplifies to this kind of "two-lever" system in the first place!)
Perhaps worth reminding readers for a while that Leo Hickman has given up pretending to be a journalist and is now a paid mouthpiece for WWF.
'I've looked at clouds from both sides now
From up and down but still somehow
Its clouds illusions I recall
I really don't know clouds at all..'
(With acknowledgements to Joni Mitchell)
LOL Sherlock 1
Positive cloud feedback is the central delusion that sustains the warming illusions in the models. In spite of the fact that clouds and temperatures wont behave well with this link in models so -
"They pay Pachauri,
To put the science in a parking lot."
[Snip - response to snipped comment]
So even more warming must have been pulled by Poseidon into the deep briny blue than was previously thought? Imagine these guys as engineers for a moment...all their structures would be upside-down or back-to-front.
I've not studied the paper yet, but an immediate reaction is that it won't please the Met Office. Although their flagship HadGEM2-ES model has a very high climate sensitivity, it sits right down with all the low sensitivity models in the dunces' corner of the paper's model performance metrics (Fig. 10).
@ sherlock1
Joni Mitchell was a better singer than most climate scientists. Perhaps she would also have made a better scientist than most of them if she had chosen a different career.