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.

What are some key research goals to better understand ocean acidification?
We know that ocean acidification is happening from direct measurements of the concentration of CO2 in the ocean. Scientists are still trying to find ways to project how organisms, food webs, and biogeochemical cycles may respond to ocean acidification. More research is needed to understand what the impacts may be on fish and shellfish harvested commercially. Most research has focused on individual organism’s response to CO2 in the lab environment. It is vital to understand the complex relationships in marine ecosystems, and to identify tolerance and thresholds to changes. Deploying a mooring system in Alaska that can monitor the changing ocean chemistry and the rate of ocean acidification will help answer many research questions. Most sensors currently deployed lack the precision required to take these measurements.

What can we do to stop ocean acidification?
Most scientists believe that the main way to slow or stop ocean acidification is to reduce fossil fuel emissions. As consumers and voters we can be vigilant about staying current on the latest research, support ways to reduce carbon emissions, inform our political representatives, and change government standards.

What can Alaskans do to adapt to uncertain, changing conditions?

• Learn more about ocean acidification by staying current on research results and news, especially to observations in Alaska and other high latitude waters.
• Review and analyze your commercial fishing business, and marine activities that might be affected by ocean acidification. List ways your livelihood or community might be impacted.
• Plan to minimize impacts. Options might include planning to diversify fishing/aquaculture operations to other species or learning new skills to diversify income and include non-fishing/aquaculture business or employment. To learn more about making and implementing adaptation strategies, review case studies, and develop planning and action tools visit the ACCAP Adaptation webpage

(Adapted from a Fact Sheet produced by Alaska Sea Grant, the Alaska Center for Climate Assessment and Policy, and the University of Alaska Fairbanks)