June 28, 2013
If Carbon Emissions Aren’t Reduced Now, Coral Reefs Will Die
Lee Rannals for redOrbit.com - Your Universe Online
A new study found that in order to prevent coral reefs from dying off, nations need to work hard to drop carbon dioxide emission levels.
Coral reefs are havens for marine biodiversity and underpin the economies of many coastal communities. They are very sensitive to changes in ocean chemistry as a result of greenhouse gas emissions, as well as pollution, warming waters, overdevelopment and overfishing.
The researchers calculated the ocean chemical conditions that would occur under different future scenarios. They used computer models to help them determine whether these chemical conditions could sustain coral reef growth.
"Our results show that if we continue on our current emissions path, by the end of the century there will be no water left in the ocean with the chemical properties that have supported coral reef growth in the past. We can't say with 100 percent certainty that all shallow-water coral reefs will die, but it is a pretty good bet," said Katharine Ricke, from the Carnegie Institute.
Coral reefs use a naturally occurring form of calcium carbonate to make their skeletons. When carbon dioxide from the atmosphere is absorbed by the ocean, it forms carbonic acid, making the ocean more acidic and decreasing the ocean's pH. This increase makes it difficult for marine organisms to grow their shells and skeletons, which inevitably threatens the coral reefs around the world.
The team said that deep cuts in emissions are necessary in order to save even a fraction of existing coral reefs. Chemical conditions that can support coral reef growth can be sustained only with very aggressive cuts in carbon dioxide emissions.
"To save coral reefs, we need to transform our energy system into one that does not use the atmosphere and oceans as waste dumps for carbon dioxide pollution. The decisions we make in the next years and decades are likely to determine whether or not coral reefs survive the rest of this century," said study coauthor Ken Caldeira of Carnegie.
Scientists wrote in May that coral reefs are definitely on the decline, but their collapse can still be avoided through local and global action.
"People benefit by reefs' having a complex structure -- a little like a Manhattan skyline, but underwater," said Peter Mumby of The University of Queensland. "Structurally complex reefs provide nooks and crannies for thousands of species and provide the habitat needed to sustain productive reef fisheries. They're also great fun to visit as a snorkeler or diver. If we carry on the way we have been, the ability of reefs to provide benefits to people will seriously decline."