"As scientists, we can study these things, but you're right, it takes a whole society to change them. The best we can do is learn as much about these changes as we can, and vote. Because it's our legislators who can actually
change things, and everybody can contribute to that solution."
Dr. Don Blankenship
Research Scientist and Director of the University of Texas Institute for Geophysics
Executive Summary
Executive Summary:
Dr. Don Blakenship along with his colleague, David Morris, joined Cyberways and Waterways to talk about their experiences studying ice sheets in Antarctica.
Here are some highlights:
Geophysicist Techniques
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A geophysicist needs to know a little bit of everything. But because we work
on things that you can't see that are underneath the surface, you need to understand how
waves propagate, and how all the different physical laws help us understand how the earth
works. So the courses that you need to take are physics, chemistry, and lots of mathematics.
But it is also important to take some geology or climatology or oceanography, so you can appreciate how the earth works as a system.
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Most often, geophysicists use seismic techniques that need an artificial source, like an
explosion or a big shaking truck. These generate sound waves that penetrate the earth,
bounce off of the interior structures, and come back to the surface, where we can observe them.
Believe it or not, it's just like a sonogram of a baby, except the earth is the mother.
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Geophysicists make hypotheses; in other words, we take a guess about how the earth
works, whether it is an ice sheet or a volcano or even an oil field, and we design
an experiment to see if our hypothesis is correct. These experiments will either
use sound waves, like the seismic experiments, or radio waves, like our radar sounding
experiments for ice sheets.
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The instruments for studying ice sheets are ice penetrating radar, and a laser altimeter,
which measures the surface position of the ice to within a few inches, measured from the
center of the earth. The instruments for studying the rocks include a magnetometer, to
look for magnetic rocks like we expect from volcanoes, and the ability to measure
gravity, which is how hard the earth's pull is, based on how the mass is distributed in the earth.
Antarctica
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We have usually been using teams of about ten people--the scientists and our assistants, who perform the measurements. Since we have so many people, we will often have other people with us to help us run the camp,
to help us do our work, so we may have as many as fifteen or so people working on a project at one time.
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A project will typically involve one to say, three or four years of field trips to Antarctica.
And it tends to work out that one project
ends as another project is beginning. So some of us may only go a year or two, and then take
a year or two off. Others have gone every year for more than ten years.
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Typically a field project will last two to three months. Since it is in the southern hemisphere, we like to do it when they have summer, which is November, December, January; a time which makes it difficult for those of
us who have families who miss being with us at that time of year.
Global Warming
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You can't just talk about the ice sheet and then its effect on the earth; the rest of the earth also
affects the ice sheet. It would take a large change in the earth's climate to cause the ice sheet to
disintegrate, and the changing of the ice sheets would contribute to how the earth's climate is changing.
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We know that the inter-glacial periods now repeat about every hundred and twenty thousand years.
This gives us the opportunity to look at previous warm periods to see how the climate changed as a
model for how the climate will change in the current warm period. Since all of the ice sheets from
this last ice age that had bottoms below sea level had disappeared in our current warm period (with
the exception of West Antarctica), the question we are interested in is whether West Antarctica
disappeared in previous inter-glacials. If so, that means we could expect it to disappear this time.
Remember that sea level will go up twenty feet if it does.
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I think these warm cold cycles ARE global warming, but what we have learned from the fact that
the climate goes through these cycles is that the climate can change very quickly and very dramatically.
From what we understand of the climate record, we are in a time of unprecedented warmth that has likely
been contributed to by human activity. It is difficult to predict with any certainty what these contributions might lead to.
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