The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), uses a completely new method of combining satellite systems to pinpoint changes and calculate the area of change over the entire tropics.
The methodology is unique because unlike previous studies, it uses a classification system that is free of human bias or methodological variance. Instead, it brings a uniform approach to tropical wide deforestation assessments that can be done in a timely, accurate and consistent manner over wide swaths of humid tropical zones.
The results show the enormity of the problem, but they are nonetheless encouraging. Policymakers, now armed with the knowledge of where these hotspots are, can use the data to make better-informed decisions about how to stop deforestation in their areas.
These findings are especially important for the current negotiations of the climate change agreement in 2012 in which forest will play a major role in the so called REDD mechanism (“Reduced emission from deforestation and forest degradation” in developing countries). Deforestation and land use change is responsible for almost 20% of the world’s emissions. Forests are therefore both part of the problem–and a major part of the solution–to combating climate change. The study will be important to the current negotiations and demonstrate the need for Brazil and Indonesia to be included and play a major role in a future climate agreement that includes forests.
A New Way to Track Changes in Forest Cover
The NAS study shows tropical deforestation with “unprecedented accuracy.” Previous studies of tree cover loss, such as those done by the UN Food and Agriculture Organisation, often relied on country-supplied data that was often unverifiable or not granular enough to isolate the worst-hit areas. In contrast, the satellite imagery used in this study is collected independently and consistently across countries and regions.
The study used medium resolution (500m) satellite imagery from the MODerate Resolution Imaging Spectroradiometer (MODIS) to pinpoint the “hotspots.” Detailed (30m) Landsat satellite images, like the ones shown below, are then used to calculate forest cover loss between 2000 and 2005. The tandem method has the great advantage to cover wide swath of areas and still come up with detailed results on area of change. Both results are important to pinpoint where conservation efforts should be concentrated. Plus, as the report points out, satellite monitoring can be done at “a fraction of the cost of obtaining extensive ground inventory data.”
Lead author Matthew Hansen of South Dakota State University (SDSU) explained how the study will improve our knowledge of deforestation dynamics. “We need operational systems that efficiently and accurately allow us to monitor forests,” Hansen said. “Consistency is paramount. Currently, we have to compare various estimates from results reflecting different periods, different study areas, different definitions and different methods. Our approach is meant to be repeatable and to cover the whole biome, which we think is an advance. Our method to could be implemented retrospectively and prospectively in monitoring change over time.”
The method described in this article were previously used by the Indonesian government in cooperation with WRI, SDSU and other organizations (e.g. World Bank, Sekala a local NGO) in a project called FOMAS (Forest Monitoring and Assessment System) that for the first time showed the changes in forest cover on an archipelago wide scale between 2000-2005. The result of this study has been used by the Indonesian government in their assessment of green-house-gas emissions from deforestation.
The “Hotspots”: Brazil and Indonesia
The majority of tropical deforestation is occurring within a few specific regions:
- 55% of clearing occurred within only 6% of the world’s forest areas.
- Just two countries–Brazil and Indonesia–accounted for just over 60% of the world’s forest loss. In both countries, forest loss is largely confined to a single state or region.
- Within Indonesia, deforestation was highly concentrated in two specific areas of peatland.
As the report points out, the numbers “reveal a higher degree of regional variation in forest clearing than currently portrayed.” In particular, the study found the worst deforestation took place in Latin America and Asia, while Africa accounted for only 5.4% of total tree clearance.
The report “may hold unexpected benefits for conservation,” co-author William Laurance, a tropical forest researcher at the Smithsonian Tropical Research Institute, said. For example, the study can show when, where and suggest why deforestation is taking place. And because forest loss appears to be much more concentrated than previously believed, it may be possible to drastically reduce deforestation by focusing efforts on a few critical regions. Using this data, advocates and government officials can now target their efforts to stop deforestation more accurately.