Deforestation
Rio+20 is taking place in Brazil, home to the largest chunk of the Amazon rainforest in the world, so it's no surprise that deforestation will be a major topic at the summit. Brazil has actually made welcome progress on reducing deforestation since the last Rio summit, with tree loss last year at its lowest level since officials started keeping track in 1988. But a new law passed by the Brazilian government just last month threatens some of that progress, while globally, efforts to connect avoided deforestation to a global carbon deal have mostly floundered. That needs to change — deforestation and degradation produces more than 10% of the world's carbon emissions, and rainforests like the Amazon are home to countless endangered species.