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November 9, 2006
CLIMATE CHANGES
ARE LINKED BETWEEN GREENLAND
AND ANTARCTIC
Even if climate
records from Greenland
and Antarctic ice cores look different, the
climate of the Artic and Antarctic are directly linked. Investigations
of an
Antarctic ice core indicate a principle connection between both
hemispheres by
a ''bipolar seesaw." Even shorter and weaker temperature changes in the
south are connected to fast changes in temperature in the north by
change of
ocean currents in the Atlantic Ocean.
Antarctica always
warmed in the time period 10,000 to
55,000 years BP whilst the North remained cold. Concurrently, warm
water export
from the Southern Ocean to the North
Atlantic
was reduced. In contrast, the Antarctic started to cool every time more
warm
water started to flow into the North
Atlantic
during warm events in the north. This result suggests a general link
between
long-term climate changes in both hemispheres via this Bipolar Seesaw
as a
result of Atlantic Meridional Overturning Circulation changes. The
Atlantic
circulation is an important issue in the global warming debate, as
icecap melt
water can weaken the Atlantic currents.
In the current issue of Nature, a
joint effort of scientists from 10 European nations working together in
the
European Project for Ice Coring in Antarctica (EPICA) established a
precise
link between climate records from Greenland and Antarctica using data
on global
changes in methane concentrations derived from trapped air bubbles in
the ice.
The Antarctic ice core analyses were performed on the new EDML (EPICA
Dronning
Maude Land) ice core, which due to its higher snow accumulation rate
allows for
reconstruction of higher resolution atmospheric and climate records
than
previous ice cores from the East Antarctic plateau; a prerequisite for
precise
synchronization with the Greenland counterpart. The Greenland
ice core analyses were performed on the North Greenland Ice core
Project
(NGRIP). Based on the new synchronized time scale the scientists were
able to
compare high-resolution temperature proxy records from north and south.
This
showed that the Bipolar Seesaw occurred throughout and most probably
beyond the
last glacial period. "It is really astounding how systematically heat
is moved
between the north and south hemisphere with the Seesaw, causing really
dramatic
climate changes during the glacial period. It is one of our goals in
our new
Centre for Interglacial Climate to investigate the importance of this
Bipolar
Seesaw in our present warm climate," says the Danish researchers from
the
Ice and Climate group at the Niels Bohr Institute, University
of Copenhagen.
The study
synchronizes the work
of EPICA scientists from 10 European countries: Belgium,
Denmark,
France,
Germany,
UK,
Italy,
the Netherlands,
Norway,
Sweden
and Switzerland.
This study is a good
example of scientist from different disciplines of ice core research
and
glaciology collaborating internationally. Modelers, isotope specialists
and
glaciologists are bringing together their expertise," says Prof. Dr
Heinz
Miller, head of the EPICA steering committee. As the Danish partner
within
EPICA, The Ice and Climate group has shipped the NGRIP deep drill to
Antarctic
every season and has taken part in the analyses on the EDML ice core.
##
Contact:
Anne
Dorte Bach
University
of
Copenhagen
453-532-4263
adba@adm.ku.dk
This text derived from:
http://www.ku.dk/english/
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