Abstract
Habitat loss imperils species both locally and globally, so protection of intact habitat is critical for slowing the rate of biodiversity decline. Globally, more than 150,000 protected areas have been designated with a goal of protecting species and ecosystems, but whether they can continue to achieve this goal as human impacts escalate is unknown. Here we show that in South Asia, one of the world's major growth epicentres, the trajectory of habitat conversion rates inside protected areas is indistinguishable from that on unprotected lands, and habitat conversion rates do not decline following gazettement of a protected area. Moreover, a quarter of the land inside South Asia's protected areas is now classified as human modified. If the global community is to make significant progress towards the Convention on Biological Diversity's Aichi Target on protected areas, there is an urgent need both to substantially enhance management of these protected areas and to develop systematic conservation outside the formal protected area system.