Projected big thaw of Antarctica`s sea ice may harm area`s unspoiled marine ecosystems

Washington: Researchers using a modeling study have suggested that the Antarctica`s Ross Sea`s recent observed increase in summer sea-ice cover is likely to be short-lived, with the area projected to lose more than half its summer sea ice by 2050 and more than three quarters by 2100.

These changes, says Professor Walker Smith of the Virginia Institute of Marine Science, will significantly impact marine life in what is one of the world`s most productive and unspoiled marine ecosystems, where rich blooms of phytoplankton feed krill, fish, and higher predators such as whales, penguins, and seals. Smith, who has been conducting ship-based fieldwork in the Ross Sea since the 1980s, collaborated on the study with colleagues at Old Dominion University. Smith said that their study predicts that it will soon reverse its present trend and experience major drops in ice cover in summer, which, along with decreased mixing of the vertical column, will extend the season of phytoplankton growth, asserting that these changes will substantially alter the area`s pristine food web. Researchers attribute the observed increase in summertime sea ice in the Ross Sea-where the number of days with ice cover has grown by more two months over the past three decades-to a complex interplay of factors, including changes in wind speed, precipitation, salinity, ocean currents, and air and water temperature. Global climate models agree that air temperatures in Antarctica will increase substantially in the coming decades, with corresponding changes in the speed and direction of winds and ocean currents. When Smith and his colleagues fed these global projections into a high-resolution computer model of air-sea-ice dynamics in the Ross Sea, they saw a drastic reduction in the extent and duration of summer sea ice. The paper has been published in journal Geophysical Research Letters.