Report: Oceans gobbling up more carbon dioxide

SeaWiFS color-codes the globe, providing scientists with valuable information about Earth

By Richard Stenger
CNN

(CNN) -- The world's plants are devouring carbon dioxide at record rates in recent years, according to data from an advanced satellite gauging carbon as it cycles through the global environment.

Observations from the orbiter should give unprecedented insight into how the planet functions and should improve models that predict global climate change, scientists said.

The amount of carbon consumed by land plants and ocean algae rose from 111 billion metric tons during the peak of the El Nino season in 1997-1998 to 117 billion metric tons during the strong La Nina that followed, according to NASA researchers.

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They based their findings on three years of global data from the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), which has ridden aboard the OrbView-2 spacecraft since 1997.

Ocean algae accounted for most if not all of the increase during the study. Land plants exhibited no such global trend, although some areas experienced noticeable changes.

The scientists, who published their findings in the journal Science this week, remain puzzled by some of the observations.

The initial increase in carbon fixation was largely due to the response of marine plants to a strong El Nino to La Nina transition, said the scientists. But the cause of the continued increase during the latter portion of the record is not yet known.

"We can see seasonal changes in plant and algae chlorophyll levels very well," said lead author and NASA oceanographer Michael Behrenfeld in a statement.

"But we don't have a long enough record to distinguish multi-year cycles like El Nino from fundamental long-term changes caused by such things as higher carbon dioxide levels in the atmosphere."

Plants and algae use chlorophyll in photosynthesis, during which they absorb carbon dioxide from the atmosphere and ocean. The process plays a critical role in regulating atmospheric carbon dioxide.

The SeaWiFS record marks the first time that a single instrument has observed the carbon intake of plants and algae worldwide. NASA plans to produce a five-year study using data from SeaWiFS and two sibling satellites, Terra, which was launched in December 1999, and Aqua, which is scheduled for launch in late 2001.

Oceanographers have used SeaWiFS to study the migration patterns of turtles, deadly blooms of algae and the long-range movement of air pollution.

El Nino and La Nina refer respectively to the periodic warming and cooling of the Pacific Ocean. The complimentary weather patterns can each last several years or longer.

They can dramatically affect the severity and number of extreme weather events across the world, including droughts, hurricanes and rainstorms; and disrupt the food chain in the oceans.

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SeaWiFS Project
NASA

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