Released by the United Nations Environment Programme (UNEP) in conjunction with climate talks in Mexico, the study, Environmental Consequences of Ocean Acidification, presents the latest research on the acidification of the world’s oceans – a phenomenon caused by increasing amounts of carbon dioxide dissolved in sea water, lowering its pH. The report said that the rate at which ocean chemistry is changing has not been seen since dinosaurs became extinct 65 million years ago, and the mean pH of the oceans has decreased by 30 percent since the industrial revolution.
UN under-secretary general and UNEP executive director Achim Steiner said: “Whether ocean acidification on its own proves to be a major or a minor challenge to the marine environment and its food chain is to date unknown. But the phenomenon comes against a backdrop of already stressed seas and oceans as a result of over-fishing to other forms of environmental degradation…It is a new and emerging piece in the scientific jigsaw puzzle, but one that is triggering rising concern".
One billion people worldwide rely on fisheries for their primary source of protein, the report said.
In particular, ocean acidification, together with ocean warming, could make it difficult for shellfish to form protective shells, and coral reefs and the fish that swim around them could also be at risk. There is also evidence that changes in the marine environment are affecting some species’ sense of smell, making it more difficult for them to navigate and avoid predators, the UNEP said.
Lead author of the report Carol Turley, of the UK Ocean Acidification Research Programme said: “We are seeing an overall negative impact from ocean acidification directly on organisms and on some key ecosystems that help provide food for billions. We need to start thinking about the risk to food security."
In order to tackle the effects of changing ocean chemistry, the report said it would be necessary to make “rapid and substantial cuts” to carbon dioxide emissions; determine vulnerability of communities dependent on marine resources; and reduce other pressures on fish stocks, among other measures.
Dr. Turley said: “It is clearly not enough to look at a species. Scientists will need to study all parts of the life-cycle to see whether certain forms are more or less vulnerable. Meanwhile, the ability, or inability, to build calcium-based skeletons may not be the only impact of acidification on the health and viability of an organism.”