The 1992 Convention on Biological Diversity (CBD) was one of the first international environmental agreements negotiated. In the same year, the Global Environment Facility (GEF) for funding biodiversity conservation in developing countries was launched. Yet 25 years later, biological populations and diversity continue to decline both on land (1) and in the oceans (2). The main reasons are chronic underfunding of global biodiversity conservation; the lack of incentives for global cooperation; and the failure to control habitat conversion, resource overexploitation, species invasions, and other drivers of biodiversity loss. Dinerstein et al. recently called for a global deal, complementing the 2015 Paris Climate Change Agreement, for conserving half of the terrestrial realm for biodiversity by 2050 (3). Here, we explore how such a deal might be implemented to overcome the funding problem in biodiversity protection.