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PD0RDD > NASA 24.10.98 20:10l 92 Lines 4631 Bytes #-10029 (0) @ WW
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Sent: 981024/1540Z @:PI8WNO.#UTR.NLD.EU #:31405 [DeMeern] FBB5.15c $:31405_PI8W
From: PD0RDD@PI8WNO.#UTR.NLD.EU
To : NASA@WW
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ANTARCTICA IS NOT SHRINKING
---------------------------
EUROPEAN SPACE AGENCY SATELLITES PROVIDE NEW INSIGHT INTO RISING SEA
LEVELS
Antarctica is not shrinking, the European Space Agency ESA reveals
today. This result of the ERS (European Remote Sensing) satellites is
reported 16 October 1998 by an international team of scientists in the
leading American magazine, SCIENCE (See note). But the same
investigation provides evidence that one part of West Antarctica may be
rapidly losing its ice to the ocean.
The team of British, Dutch and American scientists, led by Professor
Duncan Wingham at University College London, based their findings on ERS
data collected over five years.
The data reveal that most of the ice stored in Antarctica is very
stable. The icy continent now looks an unlikely source of rising global
sea level this century, making thermal expansion of the ocean due to
global warming, and the shrinking of mountain glaciers, more likely
causes.
Prof. Wingham's team used ERS's radar altimeter instruments to determine
if the thickness of the Antarctic Ice Sheet changed over the five-year
period from 1992 to 1996. Transmitting over 4,000,000 radar pulses to
the surface of the ice, and measuring the time taken for the echoes to
return to the satellite, the average change of the height of 63 of the
Ice Sheet was measured with an accuracy of 0.5 cm per year. The ice
sheet has changed on average by less than 1 cm per year. Using previous
measurements of changes in snowfall over the ice sheet, the team
concluded that the interior of the Antarctic Ice Sheet had contributed
only 1.7 cm to sea level rise this century.
Sea level has risen 18 cm over the past 100 years. Previously the
accuracy of data could have meant that Antarctica were responsible for a
raise or lowering of global sea level by 14 cm in either direction.
Speaking today on the importance of the research Professor Duncan
Wingham said: "Scientists have never really understood the role that
Antarctica has played in this century's rising sea level. Our research
makes it likely that the answer is very little."
The result supports the view that global warming, leading to a thermal
expansion of the ocean and the melting of mountain glaciers, is
responsible for rising sea level. Professor Wingham continued, "As a
consequence of our research we should be able to produce more accurate
predictions of future sea level rises. Indeed it is possible that the
consequences of global warming on sea level rise has been
underestimated."
Professor Wingham and his team also discovered a rapid reduction in
thickness in one of West Antarctica's least known drainage basins. The
Thwaites Glacier basin was shrinking rapidly at 12 cm per year. The
result provides evidence that one of the most hostile regions of
Antarctica may be undergoing rapid change.
Commenting on the wider importance of the research, ESA's Earth
Observation Mission Manager Guy Duchossois said: "Knowledge about sea
level rise matters for many million people in coastal areas whose lives
depend on dykes that can withstand the forces of nature. ESA will
continue to fly satellites that provide the data for a better
understanding of our environment. Global warming may have daunting
consequences that satellites in space can help to manage."
Further information: Franco Bonacina, Media Relations, European Space
Agency, 00 33 1 5369 7713 Patrick Edwards, Head of Media Relations, 0171
391 1621 Linda Capper, British Antarctic Survey, 01223 221 448
NOTES TO EDITORS.
(i) Antarctic Elevation Change 1992 - 1996, D.J.Wingham et al. Appears
in the 16 October 1998 edition of SCIENCE
.
Greetings from Hans at Maarssenbroek ³~ The Netherlands
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