Warm seawater is posing a tremendous threat to tropical coral, a new study has found.
Bleaching events are when unusually warm water causes coral to get rid of their symbiotic algae. That causes them to lose their colour, and turn white. Unless conditions are reversed in a relatively short amount of time, this becomes fatal for coral.
In the 1980’s these bleaching events were 25-30 years apart. According to the study, they are now only 6 years apart.
“The acceleration in the return rate of bleaching events matches up very well with what the climate models have been telling us. They predict that by mid-century, most of the world’s coral reefs will be suffering yearly, or near-yearly, heat stress,” Dr Mark Eakin told BBC News. Dr Eakin is part of the National Oceanic and Atmospheric Administration which took part in the study.
Coral provide coastal protection against big waves, storms, and floods. They are also a spawning area as well as a nursery for many economically valuable fish.
The changes being seen in the water temperature match up very well with climate change models.
It isn’t just climate change that is destroying the reefs, however. Overfishing, pollution, and habitat destruction are all playing a part.
While the authors called for renewed dedication in tackling the threat to the reefs, there were calls for more dramatic solutions. These include man-made reefs better suited to the heating waters, and research into rapidly cooling reef areas.
But co-author Prof Nick Graham from Lancaster University warns that such artificial solutions cannot truly hope to solve a problem that exists on a global level. He argues that the cost involved would be impractical and even then, it wouldn’t be able to be translated from a small scale to hundreds of thousands of square metres.
“Coral reefs cover less than 0.1% of the world’s oceans and yet they house a third of all marine biodiversity. And the oceans cover 70% of our planet so they’re housing a huge amount of the biodiversity of our planet. So, anyone who cares about extinction, about biodiversity, needs to worry about the future of coral reefs.”