Ocean acidification in Alaska’s seas

What is ocean acidification?

  • Carbon dioxide (CO2) occurs naturally in the atmosphere. Since the industrial revolution, human activities have increased the amount of CO2 in the atmosphere. The ocean acts like a big sponge and absorbs about one third to one half of human-caused CO2 emissions.
  • When CO2 dissolves in seawater, it initiates a series of chemical reactions which release hydrogen ions. An increase in hydrogen ions decreases the pH of the seawater and makes the ocean more acidic. We call this process ocean acidification.
  • Scientists are concerned about ocean acidification because of the potential impact it has on organisms that form protective shells such as coral, calcifying phytoplankton, crabs, and other shellfish. Calcium in the shells of these organisms may corrode as CO2 levels in the water increase. Ecosystems may also change with ocean acidification. How or if organisms adapt to rapidly changing conditions is unknown.
  • Ocean acidification has been seen before in the geological record, however the rate at which it is currently being observed is 100 times faster than any change in acidity experienced by marine organisms for at least the last 20 million years.

Why is it a significant concern in Alaska’s seas?
Ocean acidification is expected to occur at an accelerated rate in the ocean at the high latitudes of Alaska, the Arctic, and the Antarctic. High-latitude waters are colder and absorb more CO2 so they are already more acidic than other areas of the ocean. Continental Shelf areas in the Gulf of Alaska and Bering and Chukchi Seas are highly productive during spring and summer, so they add additional, often large, pulses of CO2 to the ocean through the process of decomposition.These areas are also connected to global-scale deep currents that serve to concentrate CO2 from carbon emissions and other sources throughout the world over long periods of time. When the deep currents reach the shallow Continental Shelf areas, upwelling occurs and brings corrosive waters to the surface where the vast majority of marine life is concentrated.

Higher ocean acidity will have direct and indirect impacts on commercially important species. Changes in the food chain could affect many animals, including humans. Many people in Alaska still live a subsistence-based lifestyle so are especially dependent on the ocean for their food supply and economic livelihood. If ocean acidification leads to a decreased population of crabs, clams and fish, the subsistence and commercial fisheries may decline, resulting in a widespread loss of traditional food gathering capability, revenue, and jobs as well as higher seafood prices at restaurants and grocery stores everywhere.

COSEE Alaska, 21 May 2010. Full article.

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