The present interest
in global climate change makes any information about Earth's climate
history valuable for modeling purposes. Thick
Antarctic ice sheets provide one of the best records for past climate
change, so a great effort has been made to collect ice cores from
some of the oldest and deepest parts of the ice sheet. The
only area where an ice core capable of providing a long, annual
history of Southern Hemisphere climate exists
is in the interior
of West Antarctica, where compressed snow layers are thick
enough to allow
Ice cores can reveal patterns of mean
They provide evidence of major volcanic
Through analysis of the air trapped in
ice bubbles, ice cores give data on the composition of the
To make the data meaningful, the levels
in the ice core must be dated.
Glaciologists use several methods, including:
counting annual layers, dating the decay rates of natural
isotopes and modeling the changes in ice flow with age.
Snow is a valuable storehouse
of information to a glaciologist.
When a snowflake falls, it brings with
it important details about the atmosphere at the time it was
As it is slowly compacted and recrystallized
by subsequent snowfalls, it forms a historical record.
Ice core researchers
in the United States are analyzing two ice cores, one from Siple
Dome, Antarctica, and one from upslope of Byrd Station in West Antarctica.
The two cores, one far inland, and one near the coast, complement
each other and allow scientists to discriminate between local and
regional influences on the climate records recovered from the cores.
The Siple Dome core comes from the Siple Coast region of Antarctica
and is situated on a dome of ice that is a thousand meters in thickness
and is expected to contain ice that is up to a hundred thousand
expect to be able to use the results from West Antarctic Ice Core
Projects to better understand the relationship between atmospheric
carbon dioxide and temperature. They
also expect to learn more about the influence of the West Antarctic
ice sheet on sea level and the likelihood for unexpected rapid changes
in sea level. Finally, they will be able to observe and record the
influence of southern ocean and atmospheric circulation patterns
on past climates.
Ice Cores So Important?
- Ice cores can reveal patterns of mean
air temperature, evidence of major volcanic eruptions and,
by analysis of the air trapped in ice bubbles, data on the
composition of the atmosphere.
- Scientists still disagree about the
effects of the present increase in carbon dioxide, therefore,
the historical record from ice cores is of considerable
- The data so far indicate that there
has been a 30% increase in the concentrations of carbon
dioxide since the last Ice Age.
- Analysis of the ice core particles will
show if they are volcanic in origin or come from dust storms
associated with more arid conditions.