Briefs

July 08, 2003. Ames Research Center

NASA is using satellite data to paint a detailed global picture of the interplay among natural disasters, human activities and the rise of carbon dioxide in the Earth's atmosphere during the past 20 years.

According to a new scientific study that appears in the July issue of the journal Global Change Biology, scientists used satellite observations to estimate the amount of leafy cover worldwide and sudden decreases in 'greenness.' Greenness is a measure of the amount of chlorophyll in live plants.

"Green leaf cover is probably the most fragile and vulnerable piece of Earth's ecosystem that scientists can easily monitor during ecological disturbances," said Christopher Potter, a scientist at NASA Ames Research Center, located in California's Silicon Valley, and the principal author of the technical paper. His co-authors include Pang-Ning Tan, Michael Steinbach and Vipin Kumar, all of the University of Minnesota, Minneapolis; Steven Klooster and Vanessa Genovese, both of California State University-Monterey Bay, Seaside, Calif.; and Ranga Myneni, Boston University, Boston.

Detecting sudden changes from large amounts of global data required the development of automated techniques that take into account the timing, location and magnitude of such changes, according to Tan.

Researchers then matched abrupt changes in plant greenness with records of large wildfires or massive crop losses to validate the study's conclusions. "The majority of the potential disturbance events that caused carbon to go into the atmosphere occurred in tropical savanna and shrub lands or in cold forest ecosystems," Klooster said.

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