Deep sea coral reefs are at risk of acidification
Howard Chew / Alamy Stock Photo
Ocean acidification is sinking regions of the sea as deep as 1,500 meters, posing new threats to organisms such as sea butterflies, sea snails and cold-water corals.
The ocean is the largest natural sink for carbon dioxide, absorbing a quarter of our annual emissions. that CO2 intake makes the surface of the ocean more acidicwith consequences for sensitive ecosystems such as coral reefs. But until now, researchers didn’t know to what extent acidification was reaching deeper waters.
Jens Daniel Müller At the Federal Institute of Technology in Zurich, Switzerland, and his colleagues developed a 3D reconstruction of how CO2 moves through the ocean, based on global measurements of currents and other circulation patterns. They used this model to estimate how carbon dioxide absorbed by the oceans Since 1800, around the beginning of the industrial revolution, it has affected the acidity of deep water.
They found a clear signal of acidification down to 1000 meters in most oceans. Certain areas, such as the North Atlantic – where powerful The South Atlantic Overturning Current (AMOC) transports carbon from the surface to deep waters – up to 1500 meters was acidification. Some deeper waters, which are naturally more acidic, saw even more acid than the surface. The higher original acidity reduces the capacity to absorb any added CO2, says Müller.
That’s what the researchers expected would happen as the ocean takes in more CO2 Hongjie Wang at the University of Rhode Island. “But it’s another thing to actually see the data that comes in to confirm that.”
Notably, half of all acidification since 1800 occurred after 1994, as our CO2 emissions have increased exponentially. “We see quite rapid progress,” says Müller.
The magnitude of acidification is sufficient to endanger the survival of organisms in large areas of the ocean. Pteropods like sea snails and sea butterflies they are particularly dangerous because they build their shells with calcium, and dissolve if the water becomes too acidic. The increase in acidification has also doubled the area where cold water corals he will have trouble surviving.
And ocean acidification will continue as the water absorbs more CO2. “Even if we were able to stop CO2 emissions immediately, we would still – for a hundred years – see a process of ocean acidification inland,” says Müller.
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