CBS News: Tropical forests are at risk of losing most of the plants and animals that now comprise their ecosystems, according to a new report from the Carnegie Institution on the effects of climate change and deforestation. In a sober appraisal of the future, the study says that the combined impact of climate change and spreading land use "represents one the greatest global change experiments on Earth today" – and not to our benefit. Among other things, the report expects deforestation and …