We stand in warm rain on a dirt road and contemplate a cattle pasture. It forms a 100-meter-wide gap, a kilometer long, between two patches of forest. Here, a few hours drive from Rio de Janeiro, our generation will make decisions that will determine whether we can sustain the present variety of life on Earth--its biodiversity. Brazil once had more than one million square kilometers of coastal forest. In the remaining 10 percent lives the largest number of species at immediate risk of extinction in the Americas.

The "we" who stand in the rain are the two of us plus our Brazilian colleague Maria Alice Alves, an ecologist from Rio de Janeiro's State University. Present, too, is the rancher who cleared the forest for his cattle, thinking that it was the best way to make money, and a representative from a local NGO (nongovernmental organization), who wants to restore the forest. We scientists might convince the international community to support that effort, but it is the three Brazilians, representing millions of others, who will actually decide their country's balance between cattle ranching and environmental stewardship.

This article was originally published with the title Sustaining the Variety of Life.

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