CO2: where it goes, nobody knows.

[CO.sub.2]: Where it goes, nobody knows

When carbon dioxide spews out of automobile tailpipes, not all of it stays in the atmosphere. Of the annual 5.3 billion tons of carbon pollution emitted each year in the form of carbon dioxide, only about 60 percent remains in the air, where it enhances Earth's greenhouse effect. The rest gets absorbed by "sinks" in the ocean and on land.

Such sinks play a critical role in limiting the pace of climate warming, but new research suggests that major errors plague scientists' estimates of carbon dioxide absorption around the world.

This disturbing conclusion emerges from a study of how tiny ocean plants called plankton affect the sequestering of carbon dioxide in the northeastern Atlantic. An intensive series of measurements revealed that the gas absorption varies greatly depending on the concentration of plant life in the surface waters, according to Andrew J. Watson from the Plymouth (England) Marine Laboratory and his colleagues. Over a distance as small as 20 kilometers, the carbon dioxide levels in the water could vary by as much as 10 percent, they report in the March 7 NATURE.

Because previous analyses of global carbon dioxide sinks have not considered such a dramatic biological influence on gas absorption. They may include significant errors, the researchers say. This finding has important implications for the ongoing debate over the location of the dominant sinks for carbon dioxide. For years, experts viewed the southern oceans as the major absorber, but evidence reported last year pointed to the land areas of the northern midlatitude as a stronger sink than previously assumed. Watson's recent ocean studies don't refute the idea of a strong northern absorber, but they do indicate that scientist lack sufficient information to discern which deserves more credit, land or sea.