Southern Ocean Cruise Probes Climate-Relevant Gases

Sea Technology, Apr 2008

In late February, more than 30 scientists embarked on a research cruise to the Southern Ocean, which surrounds Antarctica, where they will study how gases important to climate change move between the atmosphere and the ocean under high winds and seas.

The Southern Ocean Gas Exchange Experiment, a six-week cruise aboard the National Oceanic and Atmospheric Administration (NOAA) ship Ronald H. Brown, is cosponsored by the National Aeronautic and Space Administration (NASA), NOAA and the National Science Foundation.

Scientists will study the movement of gases such as carbon dioxide in an effort to improve the accuracy of climate models and predictions during the cruise, which departed February 28 from Punta Arenas, Chile.

The world's oceans are estimated to absorb about two billion metric tons of carbon dioxide from the atmosphere every year. NOAA's leading research on ocean acidification resulting from carbon dioxide uptake indicates that many organisms that support marine biodiversity may be threatened by climate change in the future.

Scientists know that higher wind speeds promote faster exchange of gases, but there have been few studies aimed at measuring these exchanges under real-world conditions.

"The Southern Ocean is the largest ocean region where the surface waters directly connect to the ocean's interior currents, providing a pathway into the deep sea for carbon dioxide released from human activities," said Christopher Sabine, an oceanographer at NOAA's Pacific Marine Environmental Laboratory in Seattle, Washington, and cochief scientist on the cruise. "Understanding how atmospheric carbon dioxide is absorbed into these cold surface waters under high winds speeds is important for determining how the ocean uptake of carbon dioxide will respond to future climate change."

"Our ongoing effort to understand the global carbon cycle will benefit from the data this cruise will produce about the mechanisms that govern gas transfer in this remote part of the world's ocean," said Paula Bontempi, manager of NASA's ocean biology and biogeochemistry research program. "And NASA's global satellite observations of ocean color that reveal so much about the health of our oceans will also be improved in this region as we validate what our space-based sensors see with direct measurements taken at sea."

Scientists from more than 20 universities and research institutions on the cruise plan to measure turbulence, waves, bubbles, temperature and ocean color relative to carbon dioxide.