premise: Since 1987, however, Brazil has taken steps to dramatically reduce the destruction, including stepped-up enforcement and the elimination of tax incentives that led to large-scale land clearing.
hypothesis: Brazil continues to clear land.
reason: There were steps taken in the 80's that doesn't mean that Brazil hasn't continued to clear its land. In fact, I believe they actually are. I think the system doesn't account for changes in policy over the passage of time.