Half Earth: promises, pitfalls, and prospects of dedicating Half of Earth's land to conservation

A growing movement of conservationists proposes to stem biodiversity losses by setting aside half of Earth's land as an interconnected global conservation reserve. As the largest land governance proposal in history, Half Earth engages with some of the wickedest challenges in land system science. How best to allocate and manage Earth's land to maximize biodiversity conservation in the face of competing demands for food, housing and other human needs? Can half of Earth's land be reallocated and governed fairly and equitably in ways that honor the rights of vulnerable populations? Who will pay for and govern this project? Half Earth's prosocial aspirational vision could help to inspire and sustain the global, regional and local efforts needed to conserve biodiversity across the Anthropocene. It is time for a broader discussion of the social-ecological opportunities, trade-offs, and challenges that a global conservation reserve project at the scale of Half Earth would create. In so doing, we must begin by recognizing the central role of social processes, institutions, and strategies in making such efforts possible, with a focus on adaptive multi-level systems of landscape governance that benefit people as much as they benefit the natural world.