Antarctic ice movements mapped
The map has been published online by Science magazine and provides
detailed images of all the great glaciers and the smaller ice streams
that feed them, BBC reported. “This is like seeing a map of all the
oceans’ currents for the first time. It's a game changer for
glaciology,” said lead author Dr. Eric Rignot.
“We are seeing amazing flows from the heart of the continent that had
never been described before,” added the NASA and University of
California (UC), Irvine, researcher.
The map which incorporates billions of radar data points collected
between 1996 and 2009 by European, Canadian and Japanese satellites
closes previous data omissions, especially in the East of the White
Continent.
“We designed acquisition plans, switching on and off the satellites,
in all the right desired geographic locations so we could fill the gaps
we didn't have data in before,” explained Dr. Mark Drinkwater of the
European Space Agency. “That was a mammoth effort.”
Scientists detected the ice movement using a technique called
Satellite Radar Interferometry (InSAR), which compares images from
repeat passes over the same location.
Antarctica houses many subglacial lakes which attract
international researchers and explorers.
Picture courtesy: Press TV |
Computer models
Authors say the West Antarctica is part of the continent
“experiencing most rapid change at present, over the widest area, and
with the greatest impact on total ice sheet mass balance”.
The Pine Island, for example, is thinning rapidly with its surface
dropping by more than 15 metres per year.
Other fast-moving streams include the Larsen B glaciers on the
Antarctic Peninsula which have experienced an eightfold increase in
speed after the floating ice shelf that bound them collapsed in 2002.
The map has also revealed a number of previously unrecognized
features including a new ridge that splits the 14 million square km
landmass from East to West.
Scientists can use the map to monitor change over time and calibrate
the computer models that are used to forecast how the ice sheet will
react to climatic changes and the surrounding ocean.
The map project was part of the 2008 International Polar Year (IPY),
a concerted research programme investigating the Earth's far North and
South regions.
Meanwhile, Russian scientists are exploring an icebound lake which
has been remained sealed deep beneath the frozen Antarctic surface for
15 million years.
“There's only a bit left to go,” chief of the Russian polar Vostok
Station Alexei Turkeyev told Reuters.
His team has drilled 3,750 metres down the Lake Vostok where the
coldest temperature ever found on Earth - minus 89.2 Celsius - was
recorded.
The largest, deepest and most isolated of Antarctica's 150 subglacial
lakes, Vostok is about the size of Lake Baikal in Siberia and is
supersaturated with oxygen, resembling no other known environment on
Earth.
“The Russians are leading the way with a torch,” said John Priscu of
Montana State University, a chief scientist with the US programme to
explore another Antarctic lake.
Ice age
Experts believe the lake is home to prehistoric or unknown life and
the Russian should rush the project to finish work before the end of the
brief Antarctic summer.
“I think Lake Vostok is an oasis under the ice sheet for life. It
would be really wild to thoroughly sample... But until we learn how to
get into the system cleanly that's an issue,” Priscu told Reuters,
adding that many creatures might exist beneath the Antarctic around
thermal vents in the depths of Lake Vostok.
Scientists think the lake might reveal new life forms and information
on how our planet looked like before the ice age and how life evolved on
Earth.
“It's like exploring an alien planet where no one has been before. We
don't know what we'll find,” said Valery Lukin of Russia's Arctic and
Antarctic Research Institute (AARI) in St Petersburg.
Pre-historic times
It has been more than 10 years since Antarctica's hidden network of
subglacial lakes were discovered via satellite imagery in the late
1990s. Now many scientists are eager to find out more about the hidden
lakes of the South Pole.
American and British explorers are also trying to get a piece of the
buried lakes with exploring some of the last unexplored reaches of the
planet.
Head of the University of Edinburgh's School of Geosciences Martin
Siegert, who is leading a British expedition to a smaller polar lake
said, “It's an extreme environment but it is one that may be habitable.
If it is, curiosity drives us to understand what's in it. How is it
living? Is it flourishing?”
The Antarctic ice crust acts like a duvet keeping the Earth's
geothermal heat inside and preventing the lakes from freezing.
Sediment from the lake could also provide scientists with information
about how life used to be in tropical prehistoric times, the AARI's
Lukin said.
Meanwhile, Marine samples collected during Captain Scott's 1900s
Antarctic expeditions are providing scientists with data that might help
tackle climate change.
Comparing Scott's samples from sea floor with modern ones showed that
the growth of bryozoans, a kind of tiny animal, has increased in recent
years, which may be due to the excessive presence of carbon dioxide on
the ocean bed.
The tiny bryozoans, Cellarinella nutti, look like a branching twig
stuck into the sea floor and grow when they can feed on planktons,
drawing them from the water with their tentacles.
As with tree rings, the length of the bryozoan's feeding season is
reflected in the size of its annual growth band, BBC reported.
According to the study published in the journal Current Biology, the
marine creatures grew roughly the same amount each year until about
1990, but their growth increased during the past decade becoming more
than double the 20th century average. Researchers from the British
Antarctic Survey (BAS) based their studies on growth rates in samples
collected in the Ross Sea, the Antarctic region where Captain Robert
Falcon Scott explored during both his Discovery (1901-04) and Terra Nova
expeditions.
BAS scientists believe the growth upturn is because the bryozoans are
eating for longer periods of time, which means they eat more
phytoplankton - tiny marine plants that draw dissolved CO2 from
seawater.
“This is important because it's locking away carbon,” said lead
researcher David Barnes. “The ‘branches’ of the bryozoans break off and
are easily buried, and we've seen that - so burial is taking carbon out
of circulation,” he added.
This is while other researchers say the Southern Ocean is
progressively absorbing less CO2.
Research network
According to findings of an international research network called the
Global Carbon Project, the size of the global sink fell by 18 percent in
the period between 2000 and 2006, with a large chunk of that decrease
registered in the Southern Ocean.
“Winds there have accelerated over the last 50 years, and it's
thought this is speeding up the mixing in the Southern Ocean and
bringing to the surface deep water that's rich in CO2,” said member of
the Global Carbon Project and director of the Tyndall Centre for Climate
Change Research Corinne Le Quere.
“So we have observations of this physical process, but the biological
activity we don't have much information about; if you're mixing the
ocean more, how are organisms responding?
“Usually in my experience the biological response compensates a bit,
but not enough and the fact that you have this one organism with higher
growth rates doesn't say how much this is going to affect the carbon
balance.”
The new findings highlight the achievements of Captain Scott and his
colleagues who could collect scientific samples from the seabed at a
depth of half a kilometre using trawls.
Press TV |