The principles of Half-Earth are informed by biologist E.O. Wilson and ecologist Robert MacArthur’s theory of island biogeography, which builds on the first principles of population ecology and genetics to explain how distance and area combine to regulate the balance between immigration and extinction in island populations. The theory puts forth that a change in habitat area results in a change in the sustainable number of species by approximately the 4th root. As reserves grow in size, the diversity of life surviving within them also grows; as reserve area is reduced, the diversity within declines swiftly and to a mathematically predictable degree, often immediately and, for some endemic species, forever.
Cuando se elimina el 90% de todo el hábitat, el número de especies que pueden persistir de forma sostenible se reduce aproximadamente a la mitad. Tal es la situación actual de muchas de las localidades más ricas en especies del mundo. En estos lugares, si también se eliminara el 10% del hábitat natural restante, la mayoría o la totalidad de las especies residentes supervivientes desaparecerían.
Si, por el contrario, protegemos una superficie suficiente, en ciertos lugares la cantidad de especies protegidas sería del 85% o más. Con aproximadamente la mitad de la superficie terrestre protegida, la biodiversidad de la Tierra entra en una zona de protección global.
The science of the Half-Earth Project aims to map and monitor biodiversity at a high-enough resolution to aid conservation decision-makers through our products, including the Half-Earth Project Map and the Species Protection Index (SPI) developed by the Map of Life at Yale University. Data sources include UNEP-WCMC, IUCN, and IPBES. The map is powered by the data storage, computational, and mapping capabilities of the Google Cloud Platform, Google Earth Engine, and Esri. Map of Life works in close collaboration with the GEO Biodiversity Observation Network (BON), E.O. Wilson Biodiversity Foundation, and in partnership with Google, Esri, NASA, the National Science Foundation, National Geographic, and other partners.