The reefs are collapsing.

Guardian takes a look underwater, and what it sees (and, more importantly, what scientists are seeing) really doesn’t look good:

The decline of the reefs has been rapid: in the 1970s, more than 50% showed live coral cover, compared with 8% in the newly completed survey. The scientists who carried it out warned there was no sign of the rate of coral death slowing.

Coral reefs are a particularly valuable part of the marine ecosystem because they act as nurseries for younger fish, providing food sources and protection from predators until the fish have grown large enough to fend better for themselves. They are also a source of revenue from tourism and leisure.

Carl Gustaf Lundin, director of the global marine and polar programme at the International Union for Conservation of Nature (IUCN), which published the research, said: “The major causes of coral decline are well known and include overfishing, pollution, disease and bleaching caused by rising temperatures resulting from the burning of fossil fuels. Looking forward, there is an urgent need to immediately and drastically reduce all human impacts [in the area] if coral reefs and the vitally important fisheries that depend on them are to survive in the decades to come.”

Last year, scientists estimated that 75% of the Caribbean’s coral reefs were in danger, along with 95% of those in south-east Asia. That research, from the World Resources Institute, predicted that by 2050 virtually all of the world’s coral reefs would be in danger.

This decline is likely to have severe impacts on coastal villages, particularly in developing countries, where many people depend on the reefs for fishing and tourism. Globally, about 275 million people live within 19 miles of a reef.