Icebergs in the Antarctic play important role in carbon cycle

Icebergs cool and dilute the ocean water they pass through and also affect the distribution carbon-dioxide-absorbing phytoplankton in the Southern Ocean, according to a team of researchers from UC San Diego and the University of San Diego.

TThe effects are likely to influence the growth of phytoplankton in the Atlantic sector of the Southern Ocean and especially in an area known as "Iceberg Alley" east of the Antarctic Peninsula.

The exposed portion of an iceberg in the Weddell Sea rises 30 to 40 meters (98 to 131 feet) above the sea surface. Overhanging icicles result from thawing and freezing of the surface of the iceberg. Photo: John Helly/SDSC

Enhanced phytoplankton growth would increase the rate at which carbon dioxide is removed from the ocean, an important process in the carbon cycle, said the leaders of the National Science Foundation (NSF)-funded study.

The results appear in the journal Deep-Sea Research II in a paper titled "Cooling, dilution and mixing of ocean water by free-drifting icebergs in the Weddell Sea." The main results from this paper were also highlighted in Nature Geoscience's March issue.

"Iceberg transport and melting have a prominent role in the distribution of phytoplankton in the Weddell Sea," said paper lead author John J. Helly, who holds joint appointments at the San Diego Supercomputer Center and Scripps Institution of Oceanography at UCSD. "These results demonstrate the importance of a multi-disciplinary scientific team in developing a meaningful picture of nature across multiple scales of measurement and the unique contributions of ship-based field research."

"The results demonstrate that icebergs influence oceanic surface waters and mixing to greater depths than previously realized," added paper co-author Ronald S. Kaufmann, Associate Professor of Marine Science and Environmental Studies at the University of San Diego.