An international movement is calling for at least half of the Earth to be allocated
for conservation. A global study now reveals that, in many ecoregions, enough
habitat exists to reach this goal, and ideas are proposed for the next steps needed.
The idea of securing at least half of the Earth for nature conservation has been gathering momentum. Various studies indicate that achieving this goal, often discussed under the name ‘Half-Earth’, coined by the biologist E. O. Wilson, would help to avoid widespread biodiversity declines, and prevent the collapse of vital services provided by ecosystems, such as carbon sequestration and climate regulation.
However, one problem with making this goal a reality is that 50% protection of all terrestrial ecosystems far exceeds current global conservation commitments. For example, the plan that is currently accepted by the United Nations Convention on Biological Diversity has a target of protecting 17% of land and freshwater regions and 10% of marine areas by 2020. The much greater scale of conservation needed for Half-Earth protection has left many people questioning whether it is even possible, given that unrelenting habitat conversion is quickly eroding opportunities for large-scale conservation. Dinerstein and colleagues have made a first attempt to answer this key question for land areas, and their findings are both encouraging and disheartening.