What Happened To the Oceans?

From this post I will talk about how the increases of concentration of atmospheric carbon dioxide affects the ocean and carbon reduction methods used related to the ocean.

Ocean acidification is one of the major results as the increases of concentration of atmospheric carbon dioxide. Frank (2004) stated that up to 30 per cent of anthropogenic CO₂ are dissolved into the oceans, lakes and rivers. Carbon dioxide reacts with water to produce carbonic acid H₂CO₃. Carbonic acid is soluble acid which gives hydronium ions (H⁺).

The chemical reaction is

CO₂ + H₂O = H₂CO₃ = 2H⁺ +CO₃^2-

As the concentration of H+ ions in the ocean increases, the acidity of the ocean rises (pH value reduces). The Copenhagen Diagnosis (2009) described that the acidity of surface ocean waters has increased by approximately 30 per cent, and the amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by near 2 billion tons per year. Currently, the average pH value of surface ocean was around 8.07, however, the value was 8.179 before industrial revolutions (Orr. 2005), meanwhile it is predicted that the average pH value of surface ocean will continue to grow , and the number may reach about 7.95 by the year 2050.

The increase of ocean acidity may cause numerous results. Firstly the change in pH value of the ocean has serious impacts on marine lives, especially oceanic calcifying organisms (e.g. corals, foraminifera and coccoliths). The rate of dissolution of calcareous material increases when the acidity rises, as a result, calcification rate of those oceanic calcifying organisms is reduced significantly.

A research by Albright (2010) specified that, by the end of this century, coral reefs will be erode quicker than they can be built. This may have massive impacts on the long-term viability of these ecosystems and perhaps affect more than one million species that depend on coral reef habitat.

The photos from National Geographic below show what happens to a pteropod’s shell when placed in sea water with pH and carbonate levels projected for the year 2100. The shell slowly dissolves after 45 days.

Reference:

• Frank, J.; et al. (July 2004). Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans. Science 305(5682).
• The Copenhagen Diagnosis: Climate Science Report:http://www.copenhagendiagnosis.org/
• Orr, James C.; et al. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437 (7059): 681–686.
• Albrighta, R.; et al. (2010) Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmate.
• What is Ocean Acidification. http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F