That’s the title of a new paper from Australian marine scientists.

“If CO2 levels are allowed to continue to approach 450 ppm (due by 2030–2040 at the current rates at which emissions are climbing), reefs will be in rapid and terminal decline world-wide from mass coral bleaching, ocean acidification, and other environmental impacts associated with climate change,” Professor Charlie Veron, Professor Hoegh-Guldberg, Dr Janice Lough of COECRS and the Australian Institute of Marine Science and colleagues warn in the scientific paper published in the Marine Pollution Bulletin.

"CO2 emissions are turning the oceans more acidic, causing damage to corals and all life with a carbonate skeletons or shells and, if unchecked, potentially leading to mass extinctions of ocean life like those of the geological past.

“We are already well above the safe levels for the world’s coral reefs. The proposed 450ppm/2 degree target is dangerous for the world’s corals and for the 500 million people who depend on them,” Professor Hoegh-Guldberg said.

“We should not go there, not only for reasons of coral reefs, but for the many other impacts that are extremely likely."