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Re: Human vs. natural influences on the environment
Leonard Evens <len@math.nwu.edu> wrote for all to see:
>Harold Brashears wrote:
[edited]
>> I think I would place less plausibility on the higher end, based on my
>> own observations of the global warming reports. Every time a new or
>> revised model is generated, I have observed a downward trend in the
>> forcast. This will probably not continue forever, but I am not yet
>> convincewd we are through, either.
>>
>> I will place much more confidence in our ability to forcast the
>> climate in one hundred years when I observe that we can take data from
>> 1920 to 1960 and predict correctly the climate in 1990. This is a
>> mere 30 years.
>>
>
>I am a bit mystefied by this comment. Why use only the data from
>1920 to 1960 and then try for 1990?
The dates were picked at random to have two characteristics:
1. The data is reliable, ie., obtained with relatively modern
instrumentation in a fairly consistent fashion.
2. That the date to be forecast be less than that of the report (100
years).
Frankly, I wanted to leave as long a baseline and as short a forecast
period as seemed reasonable. If you want a shorter baseline or a
longer forecast period, please have at it.
> As Michael Tobis and others have
>pointed out, you can prove anything you want by carefully selecting
>which dates in the record you start and finish at.
No kidding. You mean like using from 1900 to 1990 to prove that
temperatures are rising due to CO2 increase from human sources, when
the temperature increase occurred prior to 1940 - 1950, and the CO2
increase after?
>A more reasonable
>thing to do is to look at the entire observational record from some
>early base point and see how accurately the models can track it. The
>more data you try to match, the harder it is to get agreement by
>tweaking parameters. The point made by Santer and his colleagues in the
>detection chapter (8) of Climate Change, 1995 is that this is now at the
>level where we can say with confidence that human activities have
>affected climate but the uncertainties are still too large to quantify
>the human contribution.
With this part I agree.
>They also add that this does not mean that the
>human contribution is likely to be small. It could be small but it
>could just as well be large.
This was the point of my earlier post. The historical record of these
predictions shows a strong trend downward. Betting my own money, I
would bet the next such "authoritative" report will continue this
trend. Betting the public money, I am more flexible. To date, I have
seen no evidence that this trend will not continue. My bet is with
Nuremberg (that spelling does not look right?) at Scripps. Maybe 1/2
a degree over 100 hundred years.
Actually, I think he is pessimistic. I believe technology will leave
this problem behind us, unless the neoLuddites continue to have a
disproportionate voice in modern technology decisions by the
government (ie., nuclear power generation).
>It should also be added that Santer and
>his co-athors look not only at the record of average global temperatures
>but also at things like regional effects, vertical profiles of important
>variables, etc.
>
>Mr. Brashears certainly has the right to use whatever criteria he wants
>to judge the significance of the problem, but the rest of us have no
>reason to share his beliefs.
Certainly not! Did you think I claiming to be Earth First! or
Greenpeace, that I would force others to accept my beliefs?
>If we have to choose between him and
>Benjamin Santer, I think there is little doubt whom to pay more
>attention to.
And, were I alone, you would be correct. However, I must admit to a
certain disappointment in your line of argument here. This is the
first time I have seen you argue by appeal to authority. I am sorry
that you felt that was necessary to make your point, as I had thought
you more inclined to argue by evidence and logic.
My mistake. I won't repeat it. You have my apologies for bothering
you.
[deleted]
Regards, Harold
----
"We were the first to assert that the more complicated
the forms assumed by civilization, the more restricted
the freedom of the individual must become."
---Benito Mussolini
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