It is estimated that up to a fifth of the world's coral reefs have been lost and scientists are warning the rest could go by the year 2050.

An international meeting in Denmark has been told coral reefs could be preserved, by freezing samples for the future, but critics say that fails to address the root of the problem.

Al Jazeera speak to Dr Alex Rogers, a marine biologist at the Institute of Zoology in London, about the theory.

Source: Al Jazeera