Hello Steven,

It seems to me that your comments are not well-grounded, perhaps I am wrong.
Let me offer my experience in an effort to clarify for us both.  I'm
obviously biased! :-)

All  models that I have been involved with - on agriculture water & land use
issues - have begun with many trial runs to test validity of the data and
assumptions used in model construction.  These analyses were then analyzed
by professionals in the several fields involved:  agr production and yield
assumptions, current and over time, technology, water available, costs &
prices, land available and productivity, environmental factors,  etc.  For
example, I remember particularly one model 35 years ago.  When I presented
it for review by the several specialists one old agricultural specialist
sorta drawled: "Well, I see you have projected a move of the dairy industry
from Wisconsin to Iowa!"  For various institutional reasons that was not a
valid outcome in the time-frame involved.  So go back to the drawing board
to see where the data and/or assumptions were not acceptable.

Once the model was judged "reasonable" in data and basic assumptions the
analysis could begin.  First we would evaluate the situation based on the
assumption that there would be no change in poliicy/program.  This is
extremely important because it establishes a baseline that suggests the
magnitude of, for example, the potential water supply problems, if any.
Then it offers a baseline against which the several proposals to alleviate
any water supply problems that might be proposed.  These programs offer us
an opportunity to evaluate, relatively easily, many policy/program options
to enable us to better select those that are most helpful and least
damaging.

None of these analyses were "predictions" - implying factual accuracy.  They
were *projections*, implying best estimates of the relative consequences
that could be expected under the assumptions and the data available at the
time of study.

Those models were extremely important because they enabled us to incorporate
interrelationships among many activities in a way that the old hand
calculators could not provide.  And, in today's modelling world, they were
very primitive.  The model outlined above was a matrix of about 200+/-
columns and about 100+/- rows with a large percentage of empty cells.  Yet
it still took over 12 hours to run on an IBM computer complex taking up most
of a building at U. Illinois Champaign-Urbana - and that was just to see if
we had a potential feasible solution.  And we ran the problem on the
weekends to save money - it would take a weekend to get to a feasible
solution.  Today, I could run that problem on my little old desktop in
minutes.

Now the analytical capabilities are far in advance of the little work we
did.  But for me, the significance of the great expansion in computer power
is, first, the savings in time & money; second, the opportunity to
incorporate more of the complexity of the environmental problems in the
analysis.

The important ethical issues for me are whether the data and assumptions are
valid in the eyes of the professionals reviewing the work and whether the
problem is appropriate to the particular computer complex used.  In today's
world, I think that the organization and review of data and assumptions in
such large problems must be horrendous.  We should expect errors; the test -
whether there is adequate review by competent professionals of the base
program and the analyses.

And these are only projections to help society visualize the potential
problems and to get some understanding of the *relative* worthwhileness of
proposed policies/programs.

I think it would be unethical not to use the newest computer technology as
it becomes tested and available.

Steven, and all, I would appreciate any comments.

Ray
-------------

----- Original Message -----
From: "Steven Bissell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, July 25, 2001 10:16 AM
Subject: more on global warming models


> Here is another article (I haven't seen the cited article in _Science_)
that
> seems to me to be based on the use of models. This is not new evidence, it
> is just more modeling of old data and, worse, it is based on assumption
> about policy. I'm not sure this serves anyone very well.
>
> Steven
>
http://www.enn.com/news/enn-stories/2001/07/07242001/warming_44399.asp?site=
> email