Antarctic icebergs play key role in climate change
Washington: Scientists have discovered
that when Antarctic icebergs cool and dilute the seas through
which they pass for days, they also raise chlorophyll levels
in water, thus increasing carbon dioxide absorption in ocean.
An interdisciplinary research team supported, by
the National Science Foundation, claims the finding has global
implications for climate research, the 'Nature Geoscience'
The research indicates that ordinary icebergs are
likely to be more prevalent in Southern Ocean, particularly as
the Antarctic Peninsula continues a well-documented warming
trend and ice shelves disintegrate.
It also shows that these ordinary icebergs are
important features of not only marine ecosystems, but even of
global carbon cycling.
"These new findings amplify the team's
previous discoveries about icebergs and confirm that icebergs
contribute yet another, previously unsuspected, dimension of
physical and biological complexity to polar ecosystems," said
Roberta L Marinelli, Director of the NSF's Antarctic Program.
The latest findings document a persistent change
in physical and biological characteristics of surface waters
after the transit of an iceberg, which has important effects
on phytoplankton populations, clearly demonstrating "that
icebergs influence oceanic surface waters and mixing to
greater extents than previously realised, said Ronald Kaufmann
of University of San Diego.
The researchers studied the effects by sampling the
area around a large iceberg more than 32 kilometers (20 miles)
long; the same area was surveyed again ten days later, after
the iceberg had drifted away.
After 10 days, the scientists observed increased
concentrations of chlorophyll a and reduced concentrations of
carbon dioxide, as compared to nearby areas without icebergs.
These results are consistent with the growth of phytoplankton
and the removal of carbon dioxide from the ocean.
The new results demonstrate that icebergs provide a
connection between the geophysical and biological domains that
directly affects the carbon cycle in the Southern Ocean,