Ice with everything - Antarctica: Global Science from a Frozen Continent - page 87

a location where annual accumulation is as low as possible, where ice
thickness is as high as possible, and where the ice flow is dominated by vertical

thinning with limited horizontal movements. While the formula is accepted, its
success requires a great deal of sophisticated logistic and technical knowledge. The

first deep drilling operation conducted in West Antarctica, at Byrd, reached about
80 000 years back in time and characterised the climatic evolution over the past ice
age. A long-term drilling effort at Vostok provided, in the mid-1990s, 400 000 years
of climate and environmental evolution, together with the record of the deepest
ice core ever drilled on ice sheets, to a depth of more than 3600m below the snow
surface. Recently, a consortium of 12 European laboratories from 10 nations has
extracted the oldest available ice core record from Dome C, also located on the
East Antarctic Plateau. Launched in 1996, the European Project for Ice Coring in
Antarctica (EPICA) transported 1000 tonnes of material over a 1200 km traverse
from the coastal station Dumont d Urville to Dome C (Concordia Station), and

eight drillers and 20 scientists worked in the

'

field during the short summer seasons
(8 to 10 weeks from November to January), year after year, from 1996 to 2005.
A total depth of 3270m was reached, spanning the past 800 000 years. This record
duration was soon challenged by a Japanese drilling effort conducted at Dome
Fuji, which has reached an almost comparable time span, 700 000 years back in
time, and most recently a core of 3331m has been extracted by the United States
from the West Antarctic Ice Sheet, promising extraordinary high-resolution
records of the last glacial climate.
Figure 3.18 displays some of the key results obtained from the analysis of
the EPICA Dome C ice core over the past 800 000 years. The long-term climate
evolution is marked by the succession of long glacial periods, characterised by an
intense ice sheet growth in the northern hemisphere (and a decreased global sea level
by up to 120m), and relatively brief interglacial periods. The Antarctic temperature,
derived from the analysis of stable isotopes of the EPICA Dome C ice core, varies in
parallel with northern hemisphere glaciation. During ice ages, the magnitude of
Antarctic cooling reaches ~10 C, twice the estimated global cooling of ~5 C. The
long Dome C record also highlights distinct changes from one interglacial period
to the next. Prior to 400 000 years ago, interglacial periods appear as ' lukewarm ' ,

compared to the intensity of the past four warmer periods.
The last interglacial period, occurring about 130 to 115 000 years ago, is
marked in Antarctica, with temperatures 2 to 5 C above present-day levels. This
past period is particularly interesting for understanding the reactions of the ice sheet
to past climate changes. Indeed, emerged beaches and corals clearly demonstrate
that the global sea level was 5.5 to 9m above present-day, suggesting signi cant

retreat of Greenland and/or West Antarctic ice sheets. Recently, the recovery of a
north Greenland ice core extending back to the last interglacial has put strong