16 The latest report of the United Nations Intergovernmental Panel on Climate Change,issued in April, has added to concerns here. "By mid-century, increases in temperature and associated decreases in soil water are projected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia," it predicted, while also warning that "crop productivity is projected to decrease for even small local temperature increases" in tropical areas, "which would increase risk of hunger."17 Among climatologists who study the Amazon, the buzz words these days are "tipping point"——-the moment at which damage to the environment is so severe and widespread that it pushes the ecosystem into an irreversible cycle of self-destruction.18 Scientists disagree how close the Amazon is to such an event. Some warn that it is just a few years away, while others argue that the margin of safety is decades. But almost all agree that the danger exists.19 "Obviously the uncertainty range is huge, but the momentum is pushing us in that direction, and the fact that it is close is important, because the process is like steering a big ship," said Philip Fearnside, a researcher here at the National Institute for Amazon Research."People on the Titanic saw the iceberg, but they couldnt turn in time."20 In the debate over how to reduce carbon emissions and postpone or avoid such a tipping point, one area of disagreement between Brazil and the international community has been the issue of compensation for what is known as "avoided deforestation." This approach sets a monetary value for greenhouse gas emissions and pays farmers and indigenous people not to raze the forest.