The "color of life" maps will help scientists study the fate of carbon in the atmosphere, the length of growing seasons and the vitality of the ocean's food web.

Researchers expect this new detailed record of the plant life that covers land and oceans to reveal as much about how our living planet functions today as fossil and geologic records reveal about Earth's past.

The data set opens up the door to a new way of exploring Earth and making credible predictions for its life based on numerical data that previously did not exist, said Gene Carl Feldman, an oceanographer at NASA's Goddard Space Flight Center who oversees the satellite that collected the new data.

"With this data set, we can have a better level of confidence that what is happening on this planet through the use of these models is actually what is going to happen," Feldman said during a news conference at NASA Headquarters regarding the new findings.

The results, published in this week's issue of the journal Science, are based on data from the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) Project, which buys data from an instrument aboard an OrbImage satellite that takes measurements while orbiting the planet 14 times a day.

"With this record we have more biological data today than has been collected by all previous field surveys and ship cruises," Feldman said. "It would take a ship steaming at 6 knots over 4,000 years to provide the same coverage as a single global SeaWiFS image."

The new study presents a global assessment of the fundamental work that plants perform to make life possible producing food, fiber and oxygen and how their productivity changes from season to season and year to year in response to our changing environment.

Humans extract fossil fuels from Earth and produce tremendous amounts of carbon dioxide, reversing in a sense, the trend that has been going on for the past hundreds of millions of years.

Since 1800, the amount of carbon dioxide in the atmosphere has been 30 percent higher than at any time in the past 3,000 years, said Jorge Sarmiento, a geoscientist at Princeton University.

"These data are essential if we are to understand how biology functions," he said.

The biological record from SeaWiFS indicates that global plant photosynthesis increased between September 1997 and August 2000. Photosynthesis by land plants and algae absorbs carbon dioxide from the atmosphere and ocean, which plays a critical role in regulating atmospheric carbon levels. The initial increase in carbon fixation was largely due to the response of marine plants to a strong El Niño-to-La Niña transition, but the cause of the continued increase during the later portion of the record is not yet clear.

NASA plans to produce a five-year record using SeaWiFS observations and extend the continuous biological record with two Earth Observing System (EOS) spacecraft -- Terra, launched in December 1999, and Aqua, set for launch later this year. This constellation of EOS satellites should allow U.S. scientists to examine practically every aspect of Earth's atmosphere, oceans and continents from space in an unprecedented way.

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

So far, the SeaWiFS data reveal that the annual rate of carbon consumed by Earths land plants and ocean algae fluctuated between 111 billion metric tons during the peak of the 1997-98 El Nino event and 117 billion metric tons during the strong La Nina that followed.

How much carbon is that? Imagine a line of railroad cars filled with coal stretching between Earth and the Moon 45 times, Feldman said. "That's how much coal (carbon) was fixed by plants on the ground and in the ocean in a year," he said. "Half of that is made up of phytoplankton. These little microbial plants can play such a vital role in Earth's biology."

The finding is important for global carbon-cycle research because it sets a new baseline measurement for global photosynthesis, the primary pathway through which carbon enters Earths biosphere.

Also, the data show that the "greenness," or productivity, of the worlds oceans increased on a global scale during the three years of this study. No such multi-year trend was seen in land plants on a global scale, although certain regions experienced pronounced changes. The study also shows that the extent of summer phytoplankton blooms in the Northern Hemisphere exceeded those in the Southern Hemisphere.