A new study with NASA participation has sharply reduced previous estimates of how much carbon was emitted into Earth's atmosphere from tropical deforestation in the early 2000s. Research scientist Sassan Saatchi of NASA's Jet Propulsion Laboratory, Pasadena, Calif., participated in the study, published June 21 in the journal Science.

The team, led by researchers from Winrock International, an environmental nonprofit organization in Little Rock, Ark., also included scientists from Applied GeoSolutions, Durham, N.H.; and the University of Maryland, College Park. They combined satellite data on gross forest loss and forest carbon stocks to track emissions from deforestation in the world's tropical forests.

The resulting gross emissions estimate of 0.81 billion metric tons of carbon emitted per year is approximately one third of previously published estimates, and represents just 10 percent of the total global human-produced carbon emissions over the time period analyzed (2000 to 2005).