Validating Climate Models

SE has an excellent post about Validating Climate Models. It is all good, but I particularly liked

when we ask climate scientists for future projections, we're asking the question of the scientists, not of their models. The scientists will apply their judgement to select appropriate versions/configurations of the models to use, they will set up the runs, and they will interpret the results in the light of what is known about the models' strengths and weaknesses and about any gaps between the comptuational models and the current theoretical understanding. And they will add all sorts of caveats to the conclusions they draw from the model runs when they present their results.

More like this

Steve is getting better and better. The thing that Curry and Co. are missing is that he is probably THE expert in Verification and Validation from his time at IV&V

[It is very silly that Curry is writing all this stuff without having a clue, or without even knowing that she doesn't have a clue, and without knowing that the person who does is blogging just next door. Still, she seems happy to attempt to re-write Climate from the ground up on her blog. It won't work, and it isn't interesting to watch, but it keeps her followers happy. Perhaps in part because if you do it like that, you can never leave the basic level, so it all remains very easy to understand -W]…

---- brief excerpt follows -----

... Nathan Urban has been telling us about a paper where he estimated the probability that global warming will shut down a major current in the Atlantic Ocean:
⢠Nathan M. Urban and Klaus Keller, Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model, Tellus A, July 16, 2010.
... itâs also very interesting how he and Klaus Keller got their answer. As youâll see, thereâs some beautiful math involved.....

---- end excerpt ----

[Very sweet but a complete waste of time. We already know that the AMOC collapse behaviour is totally different between simple ocean models and full ocean GCMs; wrapping it all up in advanced probabililty doesn't make it any more meaningful, alas -W]

Hm. Did we also know their conclusion? I didn't. Watching a blog of physicists talk this stuff over is ... different. I'm not clear on what's new to them but old and boring here.

"Although we calculate a negligible probability that the AMOC will collapse by the end of this century, the probability that, in this century, we will commit later generations to a collapse (by 2300) is almost 5%. The probabilities of "triggering" rise rapidly, to almost 20% by 2150 and about 33% by 2200, even though the probability of experiencing a collapse by those dates is about 1% and 10%, respectively...."

They're arguing for running scenarios to 2300 or later?

Curry is attempting to use an infinite number of monkeys at typewriters to redo climate science. It will be interesting to see how long it takes, only I won't live that long.

Still it could be an interesting learning experience for her. Each thread follows the route of a swift descent into chaose, along with Oliver Manuel touting his iron sun theory. When the chaos is complete, Judith starts another thread. Rinse repeat.

Don't write off monkeys. This is reminiscent of Bob Newhart's classic classic:

"In âAn Infinite Number of Monkeys,â he imagines that although an infinite number of monkeys given enough time would type out âall the Great Books,â someone must check their work to see if they are âturning out good stuff;

in the sketch, after reading through much gibberish, one of the monitors exclaims: "Hey Harry, I think this one has got something â To be or not to be, that is the gazorninplat.â"

By John Mashey (not verified) on 05 Dec 2010 #permalink