Ocean Acidification II

The absorption of man-made CO2 emissions by the ocean has substantially lowered the seawater pH and the concentration of carbonate ions - a process called ‘ocean acidification’. The availability of carbonate ions is crucial for marine calcifying organisms to form their skeletons or shells that are made of crystalline forms of calcium carbonate. Under present-day conditions the surface waters of the ocean are super-saturated with respect to calcium carbonate, creating conditions favorable for marine calcifying organisms. The level of saturation decreases with depth in the ocean as a result of increasing carbon concentration and higher pressure. At the so called "aragonite saturation depth" the water becomes under-saturated with respect to this form of calcium carbonate which means that shells and skeletons made of aragonite start to dissolve.
This animation focuses on the Southern Ocean. The Southern Ocean is subject to a large seasonal cycle in acidity that brings waters low in calcium carbonate to the surface.  The superposition of this large annual cycle on the human-induced trend of ocean acidification make the Southern Ocean particularly vulnerable to under-saturation with respect to calcium carbonate. The animation shows a projection of how the aragonite saturation depth will shoal in the 21st century as a result of carbon dioxide emissions. As you can see, surface waters of the Southern Ocean are projected to experience under-saturation by the year 2030 with potentially severe consequences for the marine ecosystem.

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