Islands and their surrounding near-shore marine areas constitute unique ecosystems often comprising many plant and animal species that are endemic—found nowhere else on Earth. The legacy of a unique evolutionary history, these ecosystems are irreplaceable treasures. They are also key to the livelihood, economy, well-being and cultural identity of 600 million islanders—one-tenth of world population.

Island species are also unique in their vulnerability: of the 724 recorded animal extinctions in the last 400 years, about half were island species. Over the past century, island biodiversity has been subject to intense pressure from invasive alien species, habitat change and over-exploitation, and, increasingly, from climate change and pollution. This pressure is also keenly felt by island economies. Among the most vulnerable of the developing countries, small island developing States (SIDS) depend on the conservation and sustainable use of island biodiversity for their sustainable development.