Re: Global Warming

[Rick Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: "brian whatcott" <inet@INTELLISYS.NET>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, March 30, 2001 8:10 AM
Subject: Re: Global Warming


> At 19:40 3/29/01 -0700, Jim Green  wrote:
> > ...
> > 1) Is there conclusive data which supports global warming?
>
> Yes, at 1 to 20 thousand year intervals.

However, how do we know we aren't 'supposed' to be headed towards a cooling
period at this point?  The timing is about right for that too!  Data DOES
suggest that current temperature changes are upwards and quicker than
anything in the last 1000 years.

> > 2) What are/is the major gasses which contribute to global warming?
>
> CO2, Methane.
Add nitrous oxides and CFCs both of which are _only_ due to human activity.
The CO2 concentration will have doubled from pre-industrial levels by the
middle of the current century.  Data on atmospheric concentrations goes back
much farther than temperature data due to the use of trapped air in ice
cores taken from the artic.

> > 3) If there is such a thing called global warming, what percentage of the
> > effect is caused by human activity?
>
> Possibly 10%

Much more uncertain than this.  This problem is in the complex 'feedback
loops' both positive and negative that changing atmospheric concentrations
of greenhouse gasses might produce.  It is generally the severity and
direction of such feedbacks that cause the various models to widely differ
on the amount of 'man-made' temperature rise (1-10 degrees F).

> > 4) If there is such an effect, is it universally a bad thing?
>
> It is a very good thing for thermophyles

Can be great for Canada and Russia, not so good for Florida and Bangladesh
(both disappear under 3-6 foot higher oceans).
> > 5) Is it clear that such an effect could be stopped?
>
> Yes, it is clear such an effect cannot be stopped.
> And yes, it is becoming clear that such a cycle can be triggered.
Put it this way--eliminating the human changes to the atmosphere, leaving
the eco-system in a more 'natural state' [we can't exist in 6 billion plus
numbers without effecting it some] shouldn't hurt.  Trying to lower the
greenhouse emmisions seems prudent in light current trends.  Remember that
ALL the models predict man-made increases in global temperature due to
increasing concentrations of these gasses, they just don't agree on the
magnitude.

Rick

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Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

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