Evidence now suggests that continued reductions in deforestation will be hard to come by. Why? Because clear-cutters have figured out how to defeat detection efforts by targeting small parcels that are less likely to be observed by the satellites currently in use to monitor illegal logging. “The challenge has become much more difficult,” says engineer Gilberto Camara, head of INPE, Brazil’s National Institute for Space Research.

Those bi-weekly alerts have guided the nation’s environmental police, and enforcement operations have doubled in the region in the past five years. Farmers and loggers cutting down areas as large as 2,000 hectares have received hefty fines, and their properties, machinery, timber and/or cattle have been confiscated. “No one dares to chop down large areas anymore because they know they will get caught,” says geologist and geographic information system (GIS) researcher Britaldo Soares at the Federal University of Minas Gerais’s Center for Remote Sensing. The result, however, is that deforestation has become much more diffuse and difficult to halt.

The smaller parcels also mean that farmers who engage in slash-and-burn subsistence agriculture now conduct much of the clearing, rather than industrial-scale outfits. Meanwhile, the “bad guys”—big cattle ranchers and loggers—know that satellites’ optical instruments rarely detect small patches of destruction or even see them at all beneath cloud cover. So, loggers are adapting their methods to avoid detection.

Camara says that the country now needs a new real-time system with 20 times more spatial resolution than the current one to spot areas down to 0.2 square kilometer. “We are missing a great deal of degradation going under the canopy,” he explains. Both sensors used today—Modis and WFI—resolve objects down to 250 meters across. The ideal would be something between 20 and 70 meters. Some existing satellite technology can provide images with such resolution, but they take longer to obtain (Landsat provides images every 16 days) and are too expensive, because they are commercial ventures.

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*Correction (4/12/2011): This sentence was edited after posting to correct the area size comparison.