[LINK] the weather makers

[Alan L Tyree]

On Mon, 9 Apr 2007 08:19:47 +0200
Kim Holburn <kim.holburn at gmail.com> wrote:

> 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.

I tend to agree with all of the above, but the problem is that drastic
decisions are being made on the basis of the model predictions. So it
does matter. For example, clearly we do want to phase out coal. But how
fast? Even if we don't care about the 30,000 Australian miners, the
Chinese and Japanese might be a bit upset if they are suddenly deprived
of Australian coal.

So the question is: how quickly do we need to move? Are there technical
solutions? The difference between 10 years, 20 years and 50 years is
substantial. If we are going to cause substantial disruption, I would
like to know that it is necessary.

The 50 years probably came from me. Somewhat arbitrary, but the point
is that most climate change predictions are fairly long range.

> 
> > 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
> mailto:kim at holburn.net  aim://kimholburn
> skype://kholburn - PGP Public Key on request
> 
> Democracy imposed from without is the severest form of tyranny.
>                            -- Lloyd Biggle, Jr. Analog, Apr 1961
> 
> 
> 
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-- 
Alan L Tyree                    http://www2.austlii.edu.au/~alan
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