Growth rates among corals on the Great Barrier Reef have slumped to their slowest in at least four centuries and growth is expected to cease within 26 years.
The process of calcification, which gives the reefs their structure and strength, has slowed by 14.2 percent in less than 20 years, researchers in Australia have discovered.
The slowdown is so abrupt that they fear the natural process of reef-building will stop by 2050 and perhaps as early as 2035, when the Great Barrier Reef will start to fall apart.
Other reefs around the world are feared to be similarly affected, with disastrous implications for fish and other creatures. Global reef cover is already shrinking by 1 percent annually.
Stress from changes in surface temperatures and an increase in acidity caused by more carbon dioxide being absorbed by the water were cited as the most likely causes.
Scientists analysing data on 328 colonies of Porites corals collected since 1572 within the Great Barrier Reef system fear that the decline passed a "tipping point" within the past decade and may be irreversible.
Glenn De'ath, of the Australian Institute of Marine Science, said that once calcification stopped the reefs would crumble. "The reefs will slowly break down, be taken over by algae," he said. "The loss of habitat for small fish will lead to reductions in their populations, which in turn cascade up the food chain to predators, and so on. The reef will still exist, but will be very different and far less diverse."