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` journal reported.

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, Marinelli added.