Investing billions today to protect threatened ecosystems and dwindling biodiversity would reap trillions in savings over the long haul, according to a UN-backed report issued Friday. More than a billion of Earth's poorest denizens depend directly on coral reefs, forests, mangroves, aquifers and other forms of "natural capital" to eke out a living. Unless world leaders take swift action to halt the accelerating depletion of these resources, the result could be hunger, conflict and environment refugees, the study warned.