Deforestation in the Brazilian Amazon is down significantly since last year, according to preliminary estimates released by Brazil's National Institute for Space Research (INPE) and Imazon, a Brazil-based NGO that tracks forest loss and degradation across the Amazon.
Analysis of NASA MODIS data by Imazon found some 1,488 square kilometers of forest were cleared during the 12 months ended July 31, 2010, down 16 percent from the same period last year, when 1,766 square kilometers were deforested. Nearly half (47 percent) of forest loss occurred in the state of Para, where agricultural expansion is fast-expanding. Mato Grosso, the Amazon's major cattle- and soy-producing state accounted for 23 percent of deforestation during the period.
Deforestation analysis from Imazon for the previous two one-year periods, with red representing August 2009-July 2010. Imazon was originally established to ensure transparency around Brazil's reporting of deforestation statistics, which since 2003 have been posted on INPE's web site. Imazon's system is part of Google's forest monitoring platform known as the Earth Engine.
Forest loss during the most recent period contributed 95.6 million metric tons of carbon dioxide into the atmosphere, nearly the annual emissions from energy use in Greece. Emissions for the year earlier period were estimated at 121 million metric tons of carbon dioxide, according to Imazon.
Degradation—where forest is logged or burned but not entirely cleared of converted for agriculture—was nearly equivalent to deforestation for the 2009-2010 period.
Meanwhile analysis by INPE shows an even steeper drop from 4,375 square kilometers in August 2008 through July 2009 to 2,296 square kilometers in the current period, a decline of 48 percent. The discrepancy between INPE's and Imazon's estimates results from differences in how deforestation is tracked using MODIS data—Imazon uses an automatic deforestation detection method. while INPE uses mainly visual interpretation by analysts. Both use July 31, when cloud cover is minimal, as the end of the "deforestation year."
While both sets of the figures suggest a continuing decline in deforestation rates from the 2004 peak, INPE and Imazon caution the results are still preliminary based on their respective "alert" systems, which track deforestation in near real-time but at a relatively "coarser" scale that only detects areas of deforestation of greater than 25 hectares. Final data, based on analysis of higher resolution data (ares of deforestation of 6.5 hectares), will be published later this year.
Gilberto Camara, Director General of INPE, says recent trends suggest small-scale deforestation that falls below detection by INPE's DETER alert system will be an important contributor to overall over loss in 2010.
"The attached figure shows the evolution of clear-cut areas in Amazonia," he told mongabay.com via email. "Each bar graph indicates what percentage of the total deforestation was associated to clearings of a size class. So, for example, in 2002, 20% of the total deforestation area was associated with clearings less than 25 ha."
"Clearings less than 50 ha were 30% of the total in 2002, and jumped to 75% in 2009. This shows a trend towards local expansion of existing areas and a reduction on new frontier. In general terms, we see a consolidation of existing areas."