"This study found a marked trend of larger and more extensive deforestation events between 2001 and 2004 in Mato Grosso State, Brazil, which was later confirmed on the ground. Information like this is so valuable to scientists because the Amazon literally drives weather systems around the world.

The tropics receive two-thirds of the world’s rainfall, and when it rains, water changes from liquid to vapor and back again, storing and releasing heat energy in the process. With so much rainfall, an incredible amount of heat is released into the atmosphere—making the tropics the Earth’s primary source of heat redistribution. And, because of the Amazon’s location, any sort of weather hiccup from the area could signal serious changes for the rest of the world like droughts and severe storms.

Building on the results of this study, Brazil’s INPE has developed a near or almost real time monitoring application for deforestation detection known as the DETER system."

http://www.nasa.gov/centers/goddard/news/topstory/2005/amazon_deforest.html.