The history of conservation is a story of many victories in a losing war. Having served on the boards of global conservation organizations for more than 30 years, I know very well the sweat, tears and even blood shed by those who dedicate their lives to saving species. Their efforts have led to major achievements, but they have been only partly successful.

The extinction of species by human activity continues to accelerate, fast enough to eliminate more than half of all species by the end of this century. Unless humanity is suicidal (which, granted, is a possibility), we will solve the problem of climate change. Yes, the problem is enormous, but we have both the knowledge and the resources to do this and require only the will.

The worldwide extinction of species and natural ecosystems, however, is not reversible. Once species are gone, they’re gone forever. Even if the climate is stabilized, the extinction of species will remove Earth’s foundational, billion-year-old environmental support system. A growing number of researchers, myself included, believe that the only way to reverse the extinction crisis is through a conservation moonshot: We have to enlarge the area of Earth devoted to the natural world enough to save the variety of life within it.

The formula widely agreed upon by conservation scientists is to keep half the land and half the sea of the planet as wild and protected from human intervention or activity as possible. This conservation goal did not come out of the blue. Its conception, called the Half-Earth Project, is an initiative led by a group of biodiversity and conservation experts (I serve as one of the project’s lead scientists). It builds on the theory of island biogeography, which I developed with the mathematician Robert MacArthur in the 1960s.