EGU: Thursday

A view of the cathedral, which looms up over the streets on my way to the U-bahn.

Start off with a pile of global radiation / global dimming / global brightening, and indeed moisture trends (the best dataset for soil moisture comes from the FSU cos they cared about their wheat fields). A model works better to simulate soil moisture trends (increasing) if dimming taken into account.

Put up my wildly exciting sea-ice and AR4 models poster and browse amongst the others. Bit of a misc morning.

Crucifix: looking at climate sensitivity. LGM climate sens in models do not seem to be related to their CS for 2xCO2. Or for mid-holocene, or for the seasonal cycle. Because the forcing has a different pattern. What wasn’t clear was whether this affects the idea of constraining future CS by LGM bounds. Much ask Julia (or James, if you’re out there).

Krinner: why was Asia ice free in the LGM? 10/15 of PMIP models build up permament snow cover there. Suggestion: because of dust deposition there affecting the albedo. It was much dustier during the LGM, and there is a nice Gobi desert for a source, so this fits, and in his GCM it works.

Quirky poster of the day: “Do geomagnetic variations affect the foliar spiral direction of coconut palms?”. Coconut palms, apparently, grow either left or right hand spirals and this is not genetically determined; it is related to latitude, but better to geomagnetic latitude; and may well relate to earth currents. Curious. Nice to see some science-with-no-obvious-consequences still being done.

Bunk off to the Natural History museum for the afternoon, soon. First…

To Julia Hargreaves talk in the PMIP session. Its intersting stuff, or at least I think it is, because in 12 mins there was not enough time to understand it all. Or evem I fear, the main point; though it still connects to the estimating climate sensitivity, this time using proxies for LGM tropical ocean T and the MIROC gcm. I ask a “rude” question :-) (is your model good enough to be saying anything useful?) to which an ambiguous answer is returned.


  1. #1 Julia Hargreaves

    the main point is that …
    … you ought to use out of sample data that says something meaningful about the thing you are trying to predict in order to validate your estimate.

    [OK, I can go with that - W]

    In answer to your rude question – yes we showed that our prediction for the model isn’t very good, but at least we know that – most other people trying to predict climate don’t do any quantitative validation at all, so they don’t know their predictions are bunk!!!!!



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