Ocean acidification is a constant decrease in the pH level of the oceans. Ocean acidification is a direct consequence of increased anthropogenic carbon dioxide concentrations in the atmosphere. 

Technically, with the uptake of atmospheric carbon dioxide by the ocean increasing, the concentration of hydrogen ions in the ocean increases, and consequently the concentration of carbonate ions decreases—the pH level of the oceans decreases, i.e., the oceans become less alkaline. This process is known as ocean acidification.

Oceans absorb about one-third of all anthropogenic emissions from the atmosphere. Oceans are one of the largest natural carbon sinks, absorbing carbon dioxide.

Causes of Ocean Acidification

The burning of fossil fuels and the release of sulfur and nitrogen into the atmosphere by power plants and agricultural activities—causing acid rains—turn the ocean acidic.

Eutrophication leads to a decrease in seawater oxygen and an increase in CO2, eventually a decline in the pH of oceans.

Ocean Acidification | scorebetter.in
Ocean Acidification | scorebetter.in

Impact of Ocean Acidification

  • The current change in ocean chemistry (ocean acidity) is unprecedented in magnitude, occurring at a rate nearly ten times faster than anything experienced during the last hundreds of millions of years. In other words, the uptake of atmospheric carbon dioxide is happening at a rate exceeding the natural buffering capacity of the ocean.
  • This rapid change in ocean chemistry is risking the natural ability of ocean systems to adapt to changes in CO2– a process that naturally occurs over millennia. Changes in ocean pH levels will persist as long as concentrations of atmospheric CO2 continue to rise. 
  • It affects the formation and dissolution of calcium carbonate shells and skeletons in a range of marine species, including corals, molluscs such as oysters and mussels.
  • With the death of marine species, the food web gets disrupted, and eventually whole marine species extinct.
  • It affects the physiology of marine organisms and adversely affects the geographical distribution of species. For instance, the reef-building corals living in the upper tolerance level will now find it difficult and migrate to new areas with acidification.
  • Increased acidification also leads to coral bleaching-expulsion of coral’s food-producing algae- causing them to turn completely white.
  • Acidification jeopardises the role of coral reefs in buffering coastal communities from storm waves and erosion etc.
  • It impacts many other ocean-related benefits to society including the provision of food and income.

Global and National Level Efforts

  • Paris agreement sets out a legally binding framework for limiting global warming to well below 2°C and pursuing efforts to limit it to 1.5°C.
  • In INDC, India has pledged to improve the emissions intensity of its GDP by 33 to 35 percent by 2030 below 2005 levels. It has also pledged to achieve 40 percent cumulative electric power installed capacity from non-fossil-fuel energy resources by 2030.
  • Indian Government also launched several schemes like NAPCC, FAME India scheme, Barath Stage-VI, etc.

Mitigation Strategy

To reverse the inherent damage and protect the ocean ecosystem, the following mitigation strategy shall be followed:

  • Reducing and capping carbon dioxide emissions to limit the global average temperature increase to well below 2°C above preindustrial levels.
  • Regulations on offshore drilling projects.
  • Encouraging energy efficiency across the sectors.
  • Adopting alternative energy sources such as wind power, solar, etc.
  • To avoid significant harm, to atmospheric concentrations of carbon dioxide, we need to get back to at least the 320-350 ppm range of carbon dioxide in the atmosphere.
  • At the IUCN World Conservation Congress 2016, a resolution calling for the protection of 30% of the planet’s ocean by 2030 was approved.

Way Forward

Healthy oceans are crucial for the sustenance of life on earth. Hence, sustainable management, conservation, and restoration of the ocean are compulsory. 


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