Ocean acidification [UPSC]

Ocean acidification [UPSC]

Ocean acidification

Ocean acidification

  • Ocean acidification is the ongoing decrease in the pH of the Earth’s oceans, caused by
    the uptake of carbon dioxide (CO2) from the atmosphere.
  • It increases the concentration of hydrogen ions and decreases the concentration of
    carbonate ions.
  • Seawater is slightly basic (meaning pH > 7), and the process in question is a shift
    towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7).

Other factors which increases ocean acidification

Acid rain

  • It increases the acidity but impact is limited to locally and regionally (very small globally)


  • Excessive nutrients result in algal bloom which collapse and sink to the sea bed.
    Subsequent respiration of bacteria decomposing the algae leads to a decrease in sea
    water oxygen and an increase in C02 (a decline in pH).

CO2 reactions with water

2 reactions –

  • 1st reaction – Formation of carbonic acid with subsequent release of hydrogen ions.
  • 2nd reaction – between carbonate ions, C02 and water produces bicarbonate ions.
  • Combined effect of both these reactions not only increases acidity but also lowers the
    availability of carbonate ions.

Effect of ocean acidification

  • Altering the seawater chemistry of the world’s oceans
  • The ability of marine animals, most importantly pteropod molluscs, foraminifera, and
    some benthic invertebrates, to produce calcareous skeletal structures is directly
    affected. It’s like trying to build a house while someone keeps stealing your bricks.
  • It influences the physiology of marine organisms through acid-base imbalance and
    reduced oxygen transport capacity.
  • It changes the acoustic properties of sea water and also increases the ocean noise.
  • Decline in commercial fisheries


Reducing C02
Promoting government policies to cap CO2 emissions
Eliminate offshore drilling
By advocating for energy efficiency
Alternative energy sources such as wind power, solar, etc.

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