Xref: utzoo talk.politics.misc:8391 sci.misc:1032
Path: utzoo!mnetor!uunet!husc6!m2c!ulowell!bbn!bbn.com!eli
From: eli@bbn.com (Steve Elias)
Newsgroups: talk.politics.misc,sci.misc
Subject: Re: the "greenhouse effect" theory
Message-ID: <22332@bbn.COM>
Date: 19 Mar 88 16:01:45 GMT
References: <22138@bbn.COM> <114@aplcomm.UUCP> <22230@bbn.COM> <122@aplcomm.UUCP> <22276@bbn.COM> <127@aplcomm.UUCP>
Sender: news@bbn.COM
Reply-To: eli@BBN.COM (Steve Elias)
Organization: BBN Communications Corp., Cambridge, MA
Lines: 46

In <127@aplcomm.UUCP> jwm@stdc.jhuapl.edu.UUCP (James W. Meritt) writes:

>The greenhouse effect is a valid model.  It has a well-defined,justifiable
>structure, measurable inputs, produces a descriptive output cabable of being
>used to make verifiable predictions. To me this makes it valid.
>
>just for fun: valid - well grounded or justifiable, correctly derived
>from premisis.  How do YOU determine if a model is valid?
>Note: "valid", not "appropriate" nor "exhaustive"

	i consider the greenhouse model to be just a theory -- and not
	proven, workable model -- because we have yet to predict and watch
	and atmosphere go through the greenhouse effect.  we weren't around
	millions of years ago, when Venus MAY have gone through a thermal
	runaway (greenhouse effect) as we currently model it.  we don't 
	really know what happened to Venus.  we also don't know whether
	the model for the Earth is valid, because we've yet to see any
	real atmospheric changes which agree with the model.  

	my point is that a 'valid' model needs empirical results which
	agree with its predictions -- we don't have them yet.

>(As another aside, my masters is in operations research/systems analysis
>specializing in advanced modelling.  I know the problems involved in
>validating a model.)

	is empiricism involved with validating a model?  (i think so).
	as a non-expert in advanced modelling, i'd like to know.

>:	"valid model" -- meaning a model that can 
>:	actually be used to predict what the atmosphere will do: on both
>:	macro scales and local ones.
>
>:	we're nowhere near developing a model like this -- neither 
>:	our computation methods nor our sensing methods are up to the job.
>:	do you concur?  

>I do not concur on the macro scales.  The meso scale models are all right,
>but nothing to write home about.  Most of the microscale models are
>awful, and live in the heads of meterologist.  That is why the
>"local forcasts" are a running joke.

	oh well -- 2 out of 3 ain't bad...  you obviously have more
	experience with real models, but i still think that our macro
	scale models will be improved a bunch over time.  i wouldn't
	write home to Venus about any of the current models...