Earths Oceans are Becoming More Acidic

The leader of the review, John Raven of the University of Dundee, UK, says that the increase in acidity would affect the food chain, which would have potentially harmful effects on large animals. As the oceans became more acidic, it would be more difficult to extract oxygen from water. This could affect the reproduction and growth of animals with high oxygen demands, including squid. As pH fell, the proportion of dissolved forms of toxic metals would also increase.

Organisms with calcium carbonate shells, such as shellfish, certain plankton species and coral polyps, would probably feel the greatest effect. Carbonate ions, which saturate ocean water, make calcium carbonate insoluble. As the oceans’ acidity rises, the level of carbonate ions will falls, which will make it harder for animals to make their shells. In some parts of the oceans, shells could even begin dissolving.

Acidification may add to the problems endured by coral reefs, which already include global warming and acidification. Raven says we can expect to see coral reef degradation in the tropics. This would affect fisheries and tourism, and it would leave shorelines more vulnerable. Some people say that as the oceans warm up, coral reefs will grown faster, which will make up for the increased acidity. However, all studies so far suggest that coral calcification peaks at current temperatures.

As the oceans become more acidic, it may be harder for them to absorb carbon dioxide, which would intensify the problem. Currently, many coccolithophores, photosynthetic plankton that form calcium carbonate shells, sink to the bottom of the ocean, where they safely lock away huge amounts of carbon in ocean sediments. In the last 200 years, the sea has absorbed about half the carbon dioxide produced by human beings. It currently soaks up one ton of carbon dioxide gas each year for every human being on the planet. If the growth of coccolithophores is hindered, less carbon might be removed from the ocean and the atmosphere. This could speed up climate change as well as ocean acidification.

Raven claims that it would take thousands of years for natural processes to return the oceans to their pre-industrial state. The review group considered possibly neutralizing the process by dumping chalk into the sea, but concluded that the amount of chalk needed would be so great that it wouldn’t be practical. According to Andrew Watson of the University of East Anglia, UK, it would be like dumping the White Cliffs of Dover into the ocean every year. Raven says that decreasing carbon dioxide emissions is the only way to minimize the long-term consequences.