The world’s coral reefs are facing “unprecedented global bleaching” according to leading scientists. Earlier this year it was revealed that parts of the Great Barrier Reef had suffered the worst bleaching on record and there are ongoing concerns that the world’s coral reefs are still under threat.
The National Oceanographic and Atmospheric Administration (NOAA) warned this week (June 21) that forecasts show warm ocean temperatures are expected to continue to cause bleaching in the northern hemisphere.
In a statement, NOAA said: "This third global coral bleaching event that began in mid-2014 is ongoing. Global warming, coupled with an intense El Niño continues to make this the longest and most widespread coral bleaching event on record."
With so much concern over coral we explain what coral bleaching is and what it means for the future of the world’s reefs.
What is coral bleaching?
Coral bleaching occurs when the symbiotic relationship between coral and tiny marine algae (zooxanthellae) that live inside corals’ tissues breaks down. The coral expels the living algae, which gives the coral much of its colour and up to 90% of the energy required for it to grow and reproduce. Without the zooxanthellae the coral’s white skeleton is revealed leading to the term “coral bleaching”.