A studied backed by Winrock International has found evidence that recent carbon emissions from tropical deforestation are lower than other recent estimates indicate. Looking at the years 2000 to 20005, the researchers, from Applied GeoSolutions, NASA’s Jet Propulsion Laboratory, and the University of Maryland, found a gross emissions estimate of 0.81 billion metric tons per year, which is about one-third the volume of previous estimates.
The researchers note that their study uses newer data from earth-observing satellites and uses models matching areas of deforestation to their carbon content give more accurate estimates of carbon release. They contrast their approach to previous, tabular bookkeeping models, which underlie most assumptions in other climate studies.
Such bookkeeping models were developed by the Food and Agriculture Organization (FAO) and combine data for large areas. Dr. Nancy Harris, lead author of the study, says, “Tabular bookkeeping models for carbon accounting from land-use change were the best approach at the time they were developed. But the emergence of earth observing satellites combined with an international policy focus on reducing emissions from deforestation in developing countries has pushed the scientific community to adopt more transparent methods and increasingly spatial approaches to carbon accounting.”
Dr. Sandra Brown added, “It’s time to acknowledge problems with the FAO data and accept that we can now do much better. We have the ability, at last, to match the areas of forest clearing with their carbon stocks before clearing in much greater detail, allowing us to pinpoint more precisely where the highest emissions are occurring.”
The study also found that the highest emissions in the study period came from Brazil and Indonesia, which together produced 55 percent of total emissions from deforestation. The researchers found that while 40 of forest loss was from dry tropics, this accounted for only 17 percent of emissions, indicating that dry forests sequester much less carbon than do moist forests.
The team says that they hope to update their study for the period 2006 to 2010, and that their work will help to inform international actions to control deforestation and reward countries for reducing deforestation emissions. They also note that they expect that the total amount of carbon emitted from deforestation will proportionally decrease as deforestation is addressed and emissions from other areas rise.
“The relative contribution of deforestation to greenhouse gas emissions will likely continue to decline through time as emissions from other sectors rise, but the lost of millions of hectares of forest per year remains considerable,” says Dr. Alexander Lotsch. He advocates continuing efforts to reduce future deforestation and its subsequent carbon emission.
The study is published in the journal Science.