Fundamental changes in seawater chemistry are occurring throughout the world’s oceans. Since the beginning of the industrial revolution, the release of carbon dioxide (CO2) from humankind’s industrial and agricultural activities has increased the amount of CO2 in the atmosphere. The ocean absorbs about a quarter of the CO2 we release into the atmosphere every year, so as atmospheric CO2 levels increase, so do the levels in the ocean. Initially, many scientists focused on the benefits of the ocean removing this greenhouse gas from the atmosphere.  However, decades of ocean observations now show that there is also a downside — the CO2 absorbed by the ocean is changing the chemistry of the seawater, a process called OCEAN ACIDIFICATION.

Ocean acidification Process

As carbon dioxide levels go up, pH levels come down. Acidity depends on the presence of hydrogen ions (the H in pH) and more hydrogen ions mean, counterintuitively, a lower pH. Expose the surface of the ocean to an atmosphere with ever more carbon dioxide, and the gas and waters will produce carbonic acid, lowering pH on a planetary scale. The declining pH does not actually make the waters acidic (they started off mildly alkaline). But it makes them more acidic, just as turning up the light makes a dark room brighter.

Ocean acidification has further chemical implications: more hydrogen ions mean more bicarbonate ions, and fewer carbonate ions. Carbonate is what corals, the shells of shellfish and the outer layers of many photosynthesising plankton and other microbes are made of. If the level of carbonate ions falls too low the shells can dissolve or might never be made at all. There is evidence that the amount of carbonate in the shells of foraminifera, micro-plankton that are crucial to ocean ecology, has recently dropped by as much as a third.

For Ocean acidification Process Video by NOAA  Click on following link.

NOAA Environmental Visualization Laboratory – Ocean Acidification: The Other Carbon Dioxide Problem.

If some creatures can tolerate lower pHs and others cannot, you might expect things to average out: the tolerant and adaptable prosper, the more pernickety perish. For the “primary producers” in the ocean—the mostly single-celled creatures that photosynthesise—this will probably be the case. But changes in the relative prevalence of different photosynthesisers could still matter. The ecology of the oceans is all about who eats what, and small changes in the population of certain creatures near the bottom of the web could have large effects on larger ones that eat them. Some creatures may be double-whammied by having less of what they like to eat and by the pH itself, amplifying the disruption. And adaptation is not without costs: dealing with lower pH may divert a creature’s resources from other ends.

For PMEL Carbon Program Map click on Image

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