Real-Life Communication
How do scientists learn about climate change over thousands of years?
There are no weather records, but the secrets can lie inside ice. By drilling
deep into northern ice sheets, you can extract a core, which has dust, ash
and particle samples from many years ago. These can give clues about the weather.
As
a glaciologist, you would like to drill deep into the ice sheets covering
Greenland. But first, you will need to get funding for the project. You are
giving a lecture explaining why ice core data is important to understanding
climate change.
"You have to be able to justify why your work is important
if you are writing up a proposal for a research grant," says glaciologist
Martin Jeffries. "We also go to conferences and give talks, and you need to
be able to communicate your ideas clearly to others."
This is part
of what you say at the lecture:
Ice cores, cylinders of
ice drilled from polar ice sheets and high-altitude glaciers around the world,
can provide a very detailed record of climate. The record is capable of annual
and even seasonal resolution, but it is also a continuous record hundreds
of thousands of years long.
Like a movie run backward, the cores uncover
the climate story in reverse. The top layers record the most recent episodes,
while those beneath hold increasingly older information. Unlike tree rings,
ice cores carry a relatively direct record of atmospheric conditions stored
in the ice itself.
In the annual variations within glacial ice, chemicals,
ions, dust, trace metals and radioactive materials and gases are preserved.
These are used in many ways to assess different parameters of past climate.
The
air samples are of particular interest because they allow scientists to determine
the amount of CO2 and CH4 in the atmosphere as well
as the relative amounts of oxygen isotopes present in the atmosphere.
Scientists
can compare the atmospheric carbon content from many thousands of years ago
to the present value. Also, the oxygen isotopes indicate changes in global
temperatures for the time period that the ice core represents.
(Excerpted
with permission from Mark Twicklers)
The audience has
a few questions for you:
- What materials are preserved in the annual variations within glacial ice?
- Why are the air samples of particular interest?
- What can oxygen isotopes indicate?
How do you answer their questions?