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http://conservationreport.files.wordpress.com/2009/09/ocean-acidification.jpgThe ocean is a natural carbon sink: In addition to biotic carbon sequestration, the ocean naturally absorbs CO2. Consequently, when we burn fossil fuels, we release carbon that has been trapped for millions of years, and this excess carbon enters the Earth's carbon cycle.

This anthropogenically-released excess carbon is what causes ocean acidification, and the oceans have become increasingly more acidic since the industrial revolution. More on this from Physorg.com:

The chemistry is very straight-forward: ocean acidification is linearly related to the amount of CO2 we produce. CO2 dissolves in the ocean, reacts with seawater and decreases the pH. Since the industrial revolution, the oceans have become 30 percent more acidic (from 8.2 pH to 8.1 pH). "Under a "business as usual scenario, predictions for the end of the century are that we will lower the surface ocean pH by 0.4 pH units, which means that the surface oceans will become 150 percent more acidic - and this is a 'hell of a lot' ", said Jelle Bijma, chair of the EuroCLIMATE programme Scientific Committee and a biogeochemist at the Alfred-Wegener-Institute Bremerhaven.
Obviously, the impacts on calcifying organisms are worrying, because as oceans become more acidic, there is a "reduction in availability of the calcium carbonate needed for calcified shells and plates." Examples of calcifying organisms include bivalves, corals, and some plankton. Since calcifying organisms are important in maintaining ocean ecosystems, various stakeholders are concerned about the impacts of ocean acidification. The negative impacts on calcifying organisms have fishers worried about their livelihoods and recreational users of oceans, such as kayakers, are concerned about aesthetic impacts. As a result, to raise awareness, these stakeholders literally spelled out an S.O.S. on ocean acidification. More from Alaskajournal.com:

Commercial fishermen, recreational boaters and kayakers took to the waters of Kachemak Bay in Homer during the Labor Day weekend to spell out an SOS on ocean acidification and to ask the world's help in saving ocean ecosystems.

Under warm and sunny skies, interspersed at times by fog, more than 100 fishing boats, sail boats, skiffs and kayaks positioned themselves on the bay to spell out "Ocean Acid SOS."

. . .

"A lot of people have heard about climate change," said Bob Shavelson, executive director of Cook Inlet Keeper, a nonprofit group dedicated to protecting the Cook Inlet watershed. "Few have heard about ocean acidification."

Ocean acidification is caused by the excess carbon dioxide that has been released into the atmosphere since the industrial revolution, said Jeremy Mathis, a chemical oceanographer with the University of Alaska Fairbanks. The more the carbon dioxide is absorbed into the ocean, the more acidic the ocean becomes.

Mathis is one of a growing number of scientists speaking out on the dangers of ocean acidification to the ocean ecosystems. Research results released Aug. 11 by Mathis indicated that Alaska's oceans are becoming increasingly acidic, and that could damage Alaska's king crab and salmon fisheries. The results also matched his recent findings in the Chukchi and Bering seas.

Northern coastal oceans, such as those off Alaska, may be becoming more acidic than other oceans, and at a faster rate. Mathis said that the cold waters and broad, shallow continental shelves around Alaska's coast could be accelerating the process of ocean acidification in the North.

Frigid waters can absorb more carbon dioxide, he said. The shallow waters of Alaska's continental shelves also retain more carbon dioxide because there is less mixing of seawater from deeper ocean waters.
More on ocean acidification from NOAA:

The global oceans are the largest natural reservoir for carbon dioxide, and absorb approximately 30-50% of global anthropogenic CO2 emissions. In the future, increased CO2 uptake by the oceans is expected to reduce surface ocean pH by 0.3-0.5 units over the next century (Feely et al., 2004).

As carbon dioxide (CO2) reacts with seawater, fundamental chemical changes occur that cause a reduction in seawater pH (or acidification) and reduces the availability of chemical compounds which play an important role in shell creation for a number of marine organisms. Ocean acidification impacts the ability of marine calcifiers, such as corals and mollusks, to make shells and skeletons from calcium carbonate. This is due to a reduction in the availability of the chemical constituents needed for calcified shells and plates. As a result, ocean acidification could affect some of the most fundamental biological and geochemical processes of the sea in coming decades and be disruptive to the marine food web. Estimates of economic losses from coral reef degradation in the Caribbean alone range from $350-870 million/year by 2015 to coastal countries which currently receive annual economic benefits from fisheries, dive tourism, and shoreline protection services valued collectively at $3-4 billion/year (Burke and Maidens, 2004).

Data collected from ocean sampling in the Pacific Ocean from the southern to northern hemispheres confirms that the oceans are becoming more acidic, according to NOAA's Pacific Marine Environmental Laboratory (PMEL). A recently completed field study from Tahiti to Alaska collecting data about the effects of ocean acidification on the water chemistry and marine organisms found evidence that verifies earlier computer model projections. These findings are consistent with data from previous field studies conducted in other oceans.
Image by Lou Dematteis/Spectral Q/Handout via The Huffington Post

Buck Denton is currently going to law school and hopes to practice environmental law some day, but he also once worked as a NOAA contractor and instructor biologist for NOAA's Northeast Fisheries Observer Program. He created The Conservation Report in an attempt to produce a holistic, moderate, and well-informed platform for environmental news and opinion. This post was republished with permission.

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