The threat of ocean acidification

When carbon dioxide (CO2) is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals.

In their turn, Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Climate scientists estimate that the Earth’s oceans absorb 22 million tons of carbon dioxide emissions every day. In addition, half of all greenhouse gases produced by the consumption of fossil fuels are absorbed by the world’s oceans, which are steadily warming due to global climate change.

A lot of oyster growers are also worrying, they are either “extremely” or “very” concerned about ocean acidification. Many of them pointed out economic losses. Some shellfish farmers have moved their operations, while others have been forced to alter the way they operate because of changes to the oceans.

The Obama administration is developing the project, aimed to reduce carbon dioxide pollution from power plants, the source of nearly a third of the nation’s greenhouse gas emissions. The plan will result in the closure of hundreds of coal-fired power plants and encourage new investments in cleaner fuels and energy efficiency. Yet the energy industry and its foot soldiers in Congress are working to weaken or kill the plan, arguing with little justification that it will ratchet up power prices and cost thousands of jobs.

Why is it important?

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The damage extends far beyond shellfish. An Australian-led study released last week examined the impact of climate change on 13,000 marine species. While some fish species have successfully moved into cooler waters, others face extinction because of warming waters and acidification. The result is increasing acidification of the oceans, a change that is destroying coral reefs and degrading the marine food chain. That, in turn, threatens the economic future of coastal communities and businesses that rely on a healthy marine ecosystem.

Monica Green, Bulletin Leader, 4 September 2015. Article.

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