Carbon Dioxide

Ocean Acidification: The next global crisis

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Carbon dioxide is not only absorbed into the air

The addition of carbon dioxide (CO2) as the result of man-made fossil fuels has resulted in an increase in the average global surface temperature.  If left unchecked global warming might be the biggest threat to the long-term health our planet.

The carbon dioxide is emitted not only into the air but is absorbed into our oceans. The oceans are responsible for absorbing around a third of the CO2 emitted by fossil fuel burning, deforestation, and cement production. This results in a phenomenon known as ocean acidification.

The effects of Ocean Acidification

Ocean acidification describes the lowering of pH of the seawater in our oceans. Carbonic acid is formed when CO2 dissolves in seawater. The carbonic acid splits apart to produce bicarbonate ions which in turn dissociate into carbonate ions. Both reactions produce protons (H+) and therefore lower the pH of the seawater.

The average pH at the ocean surface was about 8.2 (slightly basic; 7.0 is neutral) before the industrial era began, today it is about 8.1. The change may seem small, similar natural shifts have occurred over thousands of years.  The most recent change occurred within the last 50 to 80 years.

Preventing all the carbon dioxide from being stored into the air is beneficial in terms of limiting the rise in atmospheric CO2 concentrations and hence greenhouse warming due to this CO2, there are direct consequences to the ocean’s chemistry.

A decrease in ocean pH could affect marine life in the ocean because all organisms must expend metabolic energy in maintaining the correct pH inside of their cells to ensure biochemical processes operate efficiently. Furthermore, lowered ocean pH’s result in more unexpected consequences. More acidic seawater will cause increasing noise levels in ocean and low frequency sounds will propagate farther; which will have yet unseen impacts for sonar and marine mammal (whale) communication.

The mineral calcium carbonate (CaCO3) is a fundamental building block for numerous marine organisms, from microscopic algae to reef building corals.  The ocean’s sunlit surface layer (the top 100 yards or so) could easily lose 50 percent of its carbonate ion by the end of this century. If coral carbonate production drops below the rate at which CaCO3 is being lost due to physical and bio-erosion, the reef is in danger of being eroded away.

Natural processes will eventually act to reset the chemistry of the ocean, but these processes — dissolution of carbonate sediments lying at the bottom of the ocean and the weathering of rocks on land — require many hundreds of thousands of years to occur.

Conclusion

The possible effects of ocean acidification are more reason to reduce the usage of fossil fuels before irreparable damage is done to our planet and the people who live on it.

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