Date: Wed, 18 Feb 1998 19:32:02 +0000
From: "M.A.&N.G. Jones" <Jones_M-AT-netcomuk.co.uk>
Subject: Re: M-TH: Marine biodiversity and soil fertility


                            MARIO MOLINA

Dr. Mario Molina, Massachusetts Institute of Technology.
Dr. Molina was awarded the Nobel Prize along with Dr.
Rowland for their research on the thinning of the ozone
layer. Molina and his colleagues demonstrated experimentally
how ozone-destroying chlorine functioned in the atmosphere.
He is currently the Lee and Geraldine Martin Professor of
Environmental Science at MIT. Dr. Molina serves on the
President's Committee of Advisors on Science and
Technology and has also served as an advisor to NASA, the National Science
Foundation and the National Institutes of Health.



DR. MOLINA:

…The greenhouse effect is a name of a process, a process which affects the heat
patterns of our planet.

Our earth receives energy from the sun which passes relatively freely through the
atmosphere. But the energy that the earth emits to outer space is actually trapped.
It's emitted mostly in the form of infrared radiation, and there are certain gases in
the earth's atmosphere that trap some of this radiation affecting these heat patterns.

One of these gases is carbon dioxide [CO2]. It's a very important so-called
greenhouse gas. … [G]oing back in time … 160,000 years, …we have levels of
CO2 that range between about 190 and 280 parts per million [in the atmosphere].
How do we know this? Well, it turns out that one can measure the composition of
air bubbles that are trapped in ice … cores, particularly in Antarctica … but also
Greenland. From that we can really get information about the amount of carbon
dioxide, not just locally but the amount that exists globally at that time …

…[We can also examine] a similar record of temperature, temperature going from
the present back 160,000 years. And what is very remarkable … , of course, [is] a
very large correlation between these two trends]…. [T]he pre-industrial amounts [of
CO2 were] below 300 parts per million … [compared to] where we are now, which
is roughly 365 parts per million of CO2. And what is striking is this is a level that we
haven't seen before, certainly not in … 160,000 years. And what is also very
striking is how fast we [have reached that level]….

Let me point out also that besides the very striking correlations between these two
[records], … there is an important physical mechanism that ties in now, and that's
precisely the greenhouse effect.

…The way we understand climate often is by doing computer simulations, to
…synthesize knowledge that we have -- because climate is a very complicated
system. These computer simulations are by no means perfect. But we understand,
for example, that ice ages come … from changes in the way the energy from the
sun reaches the earth, changes between the way it reaches the poles versus the
equator, [and from] changes between summer and winter. And that explains to
some extent the appearance of ice ages.

But it's not enough to look at those changes. … It's important to also consider other
effects such as the greenhouse effect from CO2: low [CO2] levels when the
temperatures are low, high [CO2] levels when the temperatures are much [higher]
…

The next question is: where are … we
heading? ... What happens in the future,
… of course, is a prediction [and]…
depends on what we do. But if we just
continue with the so-called
business-as-usual scenario, we can
predict that we are going to reach levels
way up there, about 700 parts per
million.

And what is pretty remarkable is … how fast this would occur on a geological time
scale or an evolutionary time scale. It's really like the blink of an eye. I should point
out that the earth has actually seen such high levels of CO2 in the past, but that was
some 50 million years ago. And believe me: the earth was a very different place
from what it is now….

So, [because of] … this sort of evidence, … the scientific community really
considers this to be a serious problem. …The magnitude and the pace of change …
makes us really worry and take this problem very seriously.




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