Image: NASA/SeaWiFS

Researchers have captured in unprecedented detail a record of the plant life covering Earth¿s surface. This global biological record¿based on daily observations of ocean algae and land plants from NASA¿s Sea-viewing Wide Field-of-View Sensor (SeaWiFS) mission¿will enable scientists to study the fate of atmospheric carbon, terrestrial plant productivity and the health of the ocean¿s food web. "With this record we have more biological data today than has been collected by all previous field surveys and ship cruises," says Gene Carl Feldman, SeaWiFS project manager at the NASA Goddard Space Flight Center. "It would take a ship steaming at six knots over 4,000 years to provide the same coverage as a single global SeaWiFS image." A study based on the first three years of these observations was published on Friday in the journal Science.

Intriguingly, between September 1997 and August 2000, the team found, global plant photosynthesis increased. The initial change seems to have occurred because marine algae was responding to a strong transition between El Ni¿o and La Ni¿a. But why photosynthesis continued to increase after that remains a topic for further investigation. Answers to that question and others may come once additional data has been collected from two Earth Observing System (EOS) spacecraft, which should extend this continuous SeaWiFS record.

"SeaWiFS not only adds finer detail to our observing capability," says team member James Randerson of the California Institute of Technology, "it supplies essential continuity between data records that is critical to long-term monitoring of changes in the biosphere."