One critical area of concern is the degradation of Nature and its impact on the integrity of the Biosphere and, particularly, on the massive loss of biodiversity occurring during the last century. This chapter reviews the evidence on the state of Nature and Biodiversity, as well as the main reasons behind their decline. Externalities and the absence of properties rights play an important role in this crisis, especially for the destruction of ecosystems due to changes in land use, mostly to support the expansion of food production. This pressure is especially important in poor regions, where people depend on Nature for their sustenance, and human fertility is still very high. This also presents an opportunity as carbon markets develop and eventually might be used to finance land conservation, at least for natural forest rich in carbon. In any case, there is a major role for governments to preserve and protect critical ecosystems, most of whom are in remote and poor areas in the world. Given the importance of local action, international cooperation will be needed to stop current trends in those regions.