After brief introductory comments on the Dasgupta Review, I turn to a subject little discussed in this report, the Convention on Biological Diversity. I explain the many weaknesses of this agreement, and its greatest missed opportunity: a protocol to conserve biodiversity as a global public good. This value of biodiversity represents only a fraction of the total value of conservation, but it’s the fraction that can only be supplied by a global treaty. I explain the flaws in the current approach by parties to the Convention of target setting, the advantages of a focus on biodiversity hotspots, and the reasons another treaty, the World Heritage Convention, has failed to conserve hotspots representing humankind’s biodiversity heritage. I then sketch a model showing that collective action in conserving global biodiversity hotspots can be supported by a self-enforcing treaty. The road not taken looks far more promising than the one we’ve been on since 1992.