[LINK] the weather makers

[Kim Holburn]

On 2007/Apr/09, at 7:44 AM, Alan L Tyree wrote:
> On Mon, 9 Apr 2007 06:48:22 +0200
> Kim Holburn <kim.holburn at gmail.com> wrote:
>> On 2007/Apr/08, at 11:52 PM, Alan L Tyree wrote:
>>> I would like to pick up on Stewart's point of computer modelling. I
>>> don't know the state of "verification" of these models. Most
>>> predictions are for 50 or more years into the future. I would be far
>>> more convinced if the models could be verified in one simple way:
>>> plug in the data from 1900. Does the model predict the 1940-1970
>>> cooling? Does it predict the remainder of the century?
>>
>> I watched an Attenborough show which showed the Hadley Centre which
>> Flannery also talks about.  I don't think you can talk about it like
>> that.  It's nowhere as accurate as that.  They can get a very, very
>> rough model of the last century or two.  They were showing the
>> results of modelling to demonstrate that unless they factor in man-
>> made CO2 their models are wildly out from 1970 on.
>
> That is my impression as well. They should, of course, factor in CO2,
> man made and natural. And whatever else it takes.
>
> But big political decisions are being taken on 50 year predictions. If
> it isn't "as acurate as that", then why do we think it is accurate for
> the next 50 years.

I think people seem to think that climate models should accurately  
model climate in the future.  It'd be nice but it's not necessarily  
what modelling is about.  They probably are getting more accurate,  
they are also getting more granular and able to model climate in  
different regions.

As for 50 years, I don't know if they can do anything like that.   
Where did 50 years come from anyway?  I thought political decisions  
were based on 5 year predictions.

> It's not enough to say that the trend is right. If the models are out
> by 30 or 40 or more years, then that is important to know. It makes a
> difference to our rational response.

Isn't that the whole point of models, to determine their accuracy?

--
Kim Holburn
IT Network & Security Consultant
Ph: +39 06 855 4294  M: +39 3494957443
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Democracy imposed from without is the severest form of tyranny.
                           -- Lloyd Biggle, Jr. Analog, Apr 1961