Ocean covers nearly 2/3rd of the earth's surface and play a central role in earths major processes. More than a billion people worldwide depends upon food from the ocean as their primary source of protein. Since the beginning of the industrial era, the ocean has absorbed some 525 billion tons of CO2 from the atmosphere, presently around 22 million tons per day.

At first scientist though this is a good thing as it decreases CO2 from the atmosphere but after an enhanced study it was discovered that it leads to the changing of oceans chemistry. It is estimated that about 30 to 40% of CO2 released in atmosphere is dissolved in oceans rivers and lakes out of this 25% is anthropogenic and rest is from other sources namely animals and plants. This uptake of excesses CO2 from the atmosphere into sea decreases the PH of sea and leads to oceanic acidification.

PH is a scale between 0-14 used to measure the concentration of H+ ions sea water has a PH of 7 (neither acidic nor basic) and when it decreases acidity increases so far oceans PH drops from 8.2 to 8.1 and 0.3 to 0.4 units by end of the century although it seems very low but impacts a lot. Acidity occurs when the CO2 is combined with water (H2O) and form carbonic acid (H2CO3) which act as a building blocks for the skeletons and shells of many marine organisms.

This further forms bicarbonate molecules (HCO3-) and since in water acid forms ions so H+ ions are formed. The more H+ ions are form PH decreases and acidity of the ocean increases. The rapid increase in the CO2 level jeopardizing the ocean chemistry as various calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton cannot form their shells.

Pteropod's or sea butterflies sometimes called 'potato chips of the sea' are tiny creatures and a diet for various marine animals including zooplankton, salmon, herring, birds and baleen whales a study shows that pteropod's shell dissolves over 45 day when placed in sea water and by the 2050 they will unable to make shells due to acidity and hence provide cascading effect to the marine food chain. Moreover there is total failures of developing oysters in both aquaculture facilities and natural ecosystems on the West Coast.

The West Coast oyster industry faces the consequence of 111 million dollar due to acidification. Various mollusks, including mussels, scallops and clams are near to extinction as these animals create their shells from calcium carbonate which protect their body from diseases oceanic conditions and predators due to the increase in CO2 level the concentration of H+ ions increases which does not allow the carbonate ions to combine with calcium and hence their shells were more vulnerable to dissolution due to lack of calcium carbonate (CACO3).

In a recent paper, coral biologists reported that ocean acidification could compromise the successful fertilization, larval settlement and survivorship of Elkhorn coral, an endangered species a research indicates that, by the end of this century, coral reefs may erode faster than they can be rebuilt. Although coral reefs cover just one percent of world continental shelves, coral reefs serve as important habitat to as many as 1 to 3 million species, including more than 25% of all marine fish species.

These millions of species feed, reproduce, shelter larvae and take refuge from predators in the vast three-dimensional framework offered by coral reefs these reefs are also very important to various coastal communities and economies. Economists valued the reefs to 30 to 170 billion dollars per year as these reefs provide goods and service to society including fishery, tourism, and aesthetic values costal protection. Oceanic acidification also depress the metabolic rate and immune response in marine organisms.

Currently we are forcing the marine species to live in a condition which is undesirable to them we don't know what will happen but one thing is quite clear that they will likely to be punished into extinction. Although there will be some ecological winner such as algae, sea grasses, jellyfish to whom acidity is the favorable condition as they need CO2 in large amounts to expand. But moreover we were devoid of those animals on which we depend upon and composed of those which have less value.

Apart from values excess of these species don't resembles the healthy ocean it only signifies ocean which is out of balance. In order to tackle this problem states must unanimously agree to reduce the CO2 emission from 475ppm to 350ppm, restriction must imposed on overfishing and burning of fossil fuels we should take initiative to grow mangroves, sea grasses,  salt marshes which is also known as blue carbon.

An international and national committee must be formed composed of scientist and various stakeholders which will provide detailed data, analysis, products, useful to policy advisors decision maker's politicians the members of the committee must also put a close watch on shores of oceans and insure PH does not drop to 0.2 units. Technique of iron fertilization must be adopted by different countries which provide iron to iron in poor areas of the ocean to increase photosynthesis in phytoplankton's as they are the main organism to convert excess CO2 into carbohydrate and oxygen gas.

This Oceanic acidification is also called an 'evil twin' of global warming which is responsible for climate change so by controlling one other will also get controlled. A study by Indian scientists predict that the Arabian Sea and Bay of Bengal may be hit by acidification at an unprecedented level and India being the member of Paris Accord which aims for reduction in CO2 by 2030 does not have any comprehensive legislation on CO2 emission which is the need of the hour. India's plan so far is to avoid legislation and combat the problem through policies which does not coup up with rapid changing environment and also lack accountability, legislation would bring accountability and subject to amendment to counter problem.

Apart from governmental efforts the thing which we as an ordinary citizens can do is to pledge to reduce the energy use at home by recycling, turning off unused lights, walking or biking short distances instead of driving, using public transportation, and supporting clean energy, such as solar, wind, and geothermal power. Remember oceanic acidification does not decrease immediately there is a lag between changing our emissions and when we start to feel the effects. So it's never too late to counter a problem so what we do in two to three years will determine our future.

References:

• https://www.iucn.org/resources/issues-briefs/ocean-acidification
• https://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F
• https://en.wikipedia.org/wiki/Ocean_acidification
• https://ocean.si.edu/ocean-life/invertebrates/ocean-acidification
• https://www.nationalgeographic.com/environment/oceans/critical-issues-ocean-acidification/
• https://www.britannica.com/science/ocean-acidification
• https://oceana.org/sites/default/files/reports/Ocean_Acidification_The_Untold_Stories.pdf
• https://www.pnas.org/content/107/47/20400