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Re: fHuman vs. natural influences on the environment
jscanlon@linex.com (Jim Scanlon) wrote:
>In article <4ui4cq$k7n@igc.apc.org>, tomgray <tomgray@igc.apc.org> wrote
>
>responding to charliew@hal-pc.org (charliew) statement:
>>
>> >Admittedly, there are events which have altered the
>> >atmosphere's temperature. However, if the probability is
>> >almost nil over one lifetime, I do not consider these events
>> >to be particularly relevant.
Attribution seems unclear here, so let me clarify. Charlie is the
author of the quote, with which I sharply disagreed.
>My lifetime started in 1933 at roughly the same time as the first CFC.
>When I was a child the first humans entered the stratosphere. During my
>boyhood huge fleets of airplanes entered the upper atmosphere for the
>first time: a place previously affected only by natural disturbances, >like gases and particles from violently erupting volcanoes, perhaps
>unusual variations in solar energy output and perhaps comet and
>meteor showers etc. The time span is anywhere from 3,500 to 1,000 >million years.
>
>So, in 50 years, waste gases and particles from human activity have
>resulted in measurable change in the composition and structure of the
>upper and lower atmosphere.
>
>While the change in solar radiation on the surface of the earth has, so
>far, not been catastrophic, from a homocentric point of of view, I am
>not so sure that these change (see postings on Ultraviolet increases)
>should not be considered catastrophic on a geological timescale.
I understand. Charlie, though, is speaking of "catastrophe" in a
very specialized sense: an event in which millions of people die.
>I have spoken to a number of people in several countries in South >America who told me that their skin burns faster now than
>previously. Dermatologists from two universities in Chile
>reported increased numbers of serious sunburns among fair skinned
>people earlier in the Spring, and, unusual numbers of darker
>skinned people suffering sun burned skin.(El Mercurio, 4 November
>1995)
>
>This hardly seems unusual, if one keeps in mind the estimates of a 10%
>increase in short wave ultraviolet radiation over the last ten >years.(WMO, and now GRL August 1, 1996) I started visiting Tierra del
>Fuego six years ago and spent a month on the Straight of Magellan last
>year. The weather is usually pretty bad (cold and cloudy), but I think
>it is fair to say, the people who live there are not so philosophical.
>A lot can happen in a lifetime.
True enough. I remember, for example, when the earth's population was
only 3 billion.
I think your point about the upper atmosphere is well taken, Jim.
We know that the composition and vertical temperature gradient
are changing, most likely as a result of human activity. We don't
know what the consequences of those changes will be. We assume
they will not be harmful, but given that we still can't account
for some basic things like the cause of ice ages or the cause of
the Younger Dryas, that assumption may be in error.
Tom Gray
Director of Communications
American Wind Energy Association
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Tom Gray <tomgray@econet.org>
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