Ocean life depends on single circulation pattern in Southern Hemisphere

http://www.eurekalert.org/pub_releases/2003-12/pu-old122903.php 

Study raises questions about potential impact of
climate change - A study has shown that marine life
around the world is surprisingly dependent on a single
ocean circulation pattern in the Southern
Hemisphere where nutrient-rich water rises from the
deep and spreads across the seas. The results
suggest that ocean life may be more sensitive to
climate change than previously believed because
most global warming predictions indicate that major
ocean circulation patterns will change. While
oceanographers have identified many ocean circulation
patterns, the study found that three-quarters
of all biological activity in the oceans relies on this
single pattern. "When we shut off this one pathway
in our models, biological productivity in the oceans
drops to one-quarter of what it is today," said
Jorge Sarmiento, a Princeton oceanographer who led the
study published in the Jan. 1, 2004, issue
of Nature. Marine organisms account for half all
biological productivity on Earth.