Book excerpt: The survival of the Earth's biological resources is under threat from rapidly expanding human populations that are degrading the environment at an accelerating rate. Despite the increased awareness of the importance of biological diversity, the scientific foundations on which to plan conservation and development policies are still being developed. The Global Biodiversity Assessment represents an unparalleled attempt to provide an independent scientific analysis of the current issues. It assesses the present state of knowledge, identifies gaps in understanding and draws attention to those issues where scientists have reached a consensus as well as those where uncertainty has led to conflicting viewpoints and a need for further research. The Assessment provides an unprecedented source of information for decision-makers, officials, scientists and others interested in the future of the planet.