According to a report from WWF on coral reefs, says that in a worst case scenario, there will be a collapse in coral by 2100 due to increased ocean acidification and temperatures.
The prolonged rises in the sea temperatures is a severe danger for ocean ecosystems, and many other species. Species in the oceans rely on coral reefs for their survival.
“Despite the oceans’s immensity, 71% of the Earth’s surface with an average depth of almost 4km (2½m)—there are indications that it is approaching its tipping point. For reefs, warming waters and acidification are closing in like a pair of jaws that threaten to make them the first global ecosystem to disappear.”
This was according to the Times Online: 21st-century Noah’s Ark needed to save coral reefs from extinction.