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Secrets
of the Earth's past climate locked in a three-kilometre
long Antarctic ice core are revealed this week in the
journal Nature. The core from Dome C, high on East Antarctica's
plateau, contains snowfall from the last 740,000 years
and is by far the oldest continuous climate record obtained
from ice cores so far.
The
ice has been collected in an eight year project by scientists
and engineers from 10 European countries. Analysis of
ice cores shows how temperature changed in the past, but
also how the concentrations of gases and particles in
the atmosphere varied.
The
first results confirm that over the last 740,000 years
the Earth experienced eight ice ages, when Earth's climate
was much colder than today, and eight warmer periods (interglacials).
In the last 400,000 years the warm periods have had a
temperature similar to that of today. Before that time
they were less warm, but lasted longer.
By
comparing the pattern of this past climate with global
environmental conditions today the scientists conclude
that, without human influence, we could expect the present
warm period to last at least another 15 000 years.
The
next step in the research is to extract air from tiny
bubbles in the ice, and to find out how the atmosphere's
composition has varied. Preliminary analyses show that
the present carbon dioxide concentration is the highest
level seen in the last 440,000 years. By understanding
what drove past changes in climate, the scientists expect
to improve predictions about future climate.
The
Dome C drilling is part of the 'European Project for Ice
Coring in Antarctica' (EPICA). The team at Dome C endured
summer temperatures as low as minus 40ºC at the remote
drilling site over a thousand kilometres from the nearest
research station. The consortium will continue to drill
at the site from December 2004, and hopes to reach the
rocks at the base of the ice sheet. There are just 100
metres still to drill, and if all goes well, the team
will reach ice over 900,000 years old at the base.
-ENDS-
In
the UK, issued by British Antarctic Survey Press Office
on behalf of the EPICA Steering Committee, The European
Union, and the European Science Foundation. International
press, please see contacts listed at end of release. In
the UK, please contact:
Athena Dinar - tel: (01223) 221414, mob:07740 822229,
email: a.dinar@bas.ac.uk
Linda Capper - tel: (01223) 221448, mob: 07714 233744,
email: l.capper@bas.ac.uk
Picture
Editors: Photographs and video footage of the EPICA ice
coring project and general Antarctic scenery are available
from the BAS Press Office as above.
Additional
section for UK press
Dr
Eric Wolff, from British Antarctic Survey says:
"It's very exciting to see ice that fell as snow
three-quarters of a million years ago. These results tell
us that we won't have an ice age any time soon. However,
we may have a heat wave if we are unable to control CO2
emissions and other greenhouse gases entering the atmosphere.
Our next step is to investigate CO2 in the ice cores and
by understanding what has driven the natural changes seen
in the ice record, we will create better models to predict
how climate might change in the future."
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