Prague: Coral reefs are likely to disappear from the planet by mid-century even if world leaders agree on efforts to limit a temperature increase to less than two degree Celsius by the end of the century at December's Climate Change Conference (COP21) in Paris, scientists have warned.

"Even if Paris is wildly successful, and a treaty is struck, ocean warming and ocean acidification are going to continue beyond the end of this century," said professor Peter Sale from University of Windsor in Ontario, Canada.

Speaking at a plenary session of the ongoing Goldschmidt 2015 conference, one of the world's major gathering of geochemists, in Prague, Czech Republic, Sale said he sees little hope for reefs unless the world embarks on a more aggressive emissions reduction plan.

"This is now serious; I find it very unlikely that coral reefs as I knew them in the mid-1960s will still be found anywhere on this planet by mid-century. Instead, we will have algal-dominated, rubble-strewn, slowly eroding limestone benches,” Sale pointed out.

Coral reefs are hot spots for bio-diversity and crucial for the economies of many coastal communities.

Besides providing habitats and shelter for many marine organisms, they protect coastlines from the damaging effects of wave action and tropical storms.

They are now considered one of the most vulnerable ecosystems to future climate change due to rising sea surface temperatures and ocean acidification, which is caused by higher atmospheric levels of carbon dioxide (CO2).

"Aiming for CO2 at 350 ppm (parts per million), or a total warming of around 1C is scientifically defendable, and would give reefs a good chance; a number of coral reef scientists have called for this,” Sale noted.

"This is a global emergency, which requires us to decarbonise within the next 20 years, or face temperatures that will eliminate ecosystems like coral reefs, and indeed many systems that humans depend on," said professor Ove Hoegh-Guldberg from University of Queensland in Australia.