Perilous Times and Climate Change
The Ice At The South Pole Is Melting
It has long been known that the Pacific El Nino climate phenomenon and
the snowfall in Antarctica are linked.
by Staff Writers
Berlin, Germany (SPX) Nov 02, 2010
The change in the ice mass covering Antarctica is a critical factor in
global climate events. Scientists at the GFZ German Research Centre for
Geosciences have now found that the year by year mass variations in the
western Antarctic are mainly attributable to fluctuations in
precipitation, which are controlled significantly by the climate
phenomenon El Nino.
They examined the GFZ data of the German-American satellite mission
GRACE (Gravity Recovery and Climate Experiment). The investigation
showed significant regional differences in the western coastal area of
the South Pole area.
Two areas in Antarctica are of particular interest because of their
potential sensitivity to global climate change: the Antarctic
Peninsula, which is currently experiencing a warming exceeding the
global mean and the disappearance of large ice shelf areas, and the
Amundsen Sector of West Antarctica, where currently the largest flow
rates and mass loss of the Antarctic Ice Sheet is occurring.
For some glaciers the ice thickness is decreasing rapidly, and glaciers
and ice streams are notably retreating back into the interior. With 0.3
millimeters per year, both regions are currently contributing
considerably to the global sea level change of about three millimeters
per year.
In the study, the mass balance of both regions is reevaluated from
gravity data of the satellite mission GRACE. As a result, the estimates
were lower than those of conventional mass balance methods.
"With the GRACE time series, it was for the first time possible to
observe how the large-scale ice mass varies in the two areas due to
fluctuations in rainfall from year to year," said the GFZ scientists
Ingo Sasgen.
It has long been known that the Pacific El Nino climate phenomenon and
the snowfall in Antarctica are linked. The complementary piece to the
warm phase El Nino, the cold phase known as La Nina, also affects the
Antarctic climate: "The cooler La Nina years lead to a strong low
pressure area over the Amundsen Sea, which favors heavy rainfall along
the Antarctic Peninsula - the ice mass is increasing there.
In contrast, the Amundsen area is dominated by dry air from the
interior during this time. El Nino years with their warm phase lead to
precisely the opposite pattern: reduced rainfall and mass loss in the
Antarctic Peninsula, and an increase in the Amundsen Sectorfield,
respectively" explains Professor Maik Thomas, head of the section
"Earth System Modelling" at the German Research Centre for Geosciences
(Helmholtz Association).
The recording of the entire ice mass of the South Pole and its
variations is a central task in climate research and still raises many
unanswered questions. In principle, the study could show that the
continuous gravity data of the GRACE satellite mission contain another
important medium-term climate signal.
Sasgen, I. Dobson, H., Martinec, Z. and Thomas, M., "Satellite
Gravimetry Observation of Antarctic Snow Accumulation Related to ENSO,"
Earth and Planetary Science Letters (2010), doi: 10.1016/j.epsl.2010.09
.015.