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Ocean Acidification Will Increase in Years To Come

Scientists are warning that the world’s oceans are becoming acidic at an unparalleled rate, which could have a harmful bang on marine life and the hundreds of millions of people who depend on fishing for their living. Ocean acidity is expected to be more than double by 2100 because of fossil-fuel pollution, putting fisheries at risk and diminishing the capacity of the seas to absorb carbon-dioxide emissions, a study showed.

The seas have already acidified by 26 percent since industrialization commenced two centuries ago, and a persistence of current system may lead to a 170 percent increase in acid levels by the end of the century, according to the study released at the United Nations climate talks recently in Warsaw.

A study previously this year showed oceans which absorb CO2 from the atmosphere, forming carbonic acid are acidifying at their fastest pace in 300 million years. Because the level of acidity can affect the capability of creatures to form shells, the resulting damage could cost the shellfish industry $130 billion a year, according to Unesco study. Negotiators in the Polish capital are working to craft by 2015 a treaty to limit from 2020 the carbon emissions that cause both global warming and ocean acidification.

“Substantial changes in marine ecosystems are expected and they are likely to have a major socioeconomic impact,” the United Nations Educational, Scientific and Cultural Organization said in a statement. “This phenomenon is all the more worrying in view of other threats to marine ecosystems such as rising water temperatures, overfishing and pollution.”

The oceans sop up about a quarter of CO2 emissions from human activity, according to the researchers. As its acidity increases, its ability to absorb the gas diminishes, threatening to heighten global warming because more heat-trapping CO2 will remain in the atmosphere, they said.

“If we don’t do something about it and we follow a high CO2 scenario, we will see both global warming and the acidification of the oceans,” Carol Turley, a senior scientist at the Plymouth Marine Laboratory in southwest England, said today in Warsaw.

The study was assembled by Unesco’s Intergovernmental Oceanographic Commission, the Scientific Committee on Ocean Research and the International Geosphere-Biosphere Program. It represents the conclusions of 540 ocean scientists from 37 nations.

Urchins to face direct effect

Spiny green sea urchins are predicted to face the direct effect of these climate changes. As the oceans become more acidic, urchin larvae fight to digest their food, according to another research. The study is the first to demonstrate that ocean acidification can cause digestive problems for marine animals, though scientists have long been worried at the drift for other reasons. Ocean acidification has endangered oyster farms, slowed coral growth and caused common marine snails to shrink, among other effects.

Earlier studies have focused on calcification, or the process by which marine animals draw minerals from the water to build shells and skeletons, study researcher Meike Stumpp, a former Ph.D. student at the GEOMAR Helmholtz Center for Ocean Research and the University of Kiel in Germany, said in a statement.
“Other vital processes — such as digestion and gastric pH regulation — were neglected,” Stumpp said. Gastric pH is the level of acidity in the digestive system. “We can now demonstrate that they deserve much more attention,” she said.

As levels of carbon dioxide in the atmosphere extend the oceans act as a dab, taking up some of the extra carbon dioxide. The result is carbonic acid, which decreases the overall pH of the oceans. Since the Industrial Revolution, the ocean has become about 25 to 30 percent more acidic, scientists approximate.

Acidification eats away at minerals used by corals to build their skeletons and other animals to build their shells. But Stumpp and her colleagues were concerned with another part of the life cycle. Many marine animals start their lives as larvae, which are very exposed to the ocean environment. In particular, the larvae of the green sea urchin (Strongylocentrotus droebachiensis) have a digestive system that is bathed in ocean water.

Humans and other mammals have acidic gastric juices with a pH measurement of around 2, similar to the acidity level of lemon juice. Sea-urchin larvae, in contrast, have very basic, or alkaline, digestive juices — about 9.5 on the 14-point pH scale. Historically, ocean pH was about 8.16 on the pH scale, making it slightly less basic than urchin digestive juices.