Coral reefs rank as some of the planet’s most vital ecosystems. Although they cover just 0.2 percent of oceans, reefs are home to a quarter of marine biodiversity. Scientists warn they could vanish in as little as a decade, unless we rapidly slow the rate of global warming. In Monaco, a team of scientists have decided to create a "Noah's Ark" for coral reefs, hoping to collect and preserve all species known to humankind before it's too late. Our Down to Earth team reports.