There has been a looming threat to our marine life which oceanographers, across the globe, have been monitoring closely in recent years. The increasing carbon emission from the anthropogenic activities and the growing human population has led to a new phenomenon called ocean acidification. On a pH scale, zero is most acidic and 14 is most basic while 7 being neutral. Ocean water is basic, somewhere at the pH level of 8.1. However, as the CO2 level continues to grow in the air, oceans have been absorbing more CO2 which is lowering the pH of ocean water, making is less basic. This is called ocean acidification. Most forms of the carbonate ions are being used up in buffering action to maintain basicity of water; the carbonates ions which, earlier, were readily available to be used up by Molluscs and other shelled animals–like corals, shrimps, oysters, lobsters–to make their shells have been decreasing and this is leading to the softening and erosion of their shells.
Australia’s Great barrier reef, too, has been affected by it. The coral reefs, because of rising sea temperature and lack of enough carbonate absorption, are getting bleached and it is expected that we might have lost half of it already! Major ocean acidification has been observed in polar areas, specifically in the Arctic ocean, twice the rate of the Atlantic and Pacific ocean, where the cold temperature of water absorbs carbon dioxide more rapidly. Low availability of carbonates does not let shelled creatures maintain their shells. This is affecting the fishery industry and, which, in turn, will affect the food web of many animals and human beings.
A recent study suggests that 253 million years ago, massive volcanic eruptions led to extreme oceanic acidification which may have caused a mass extinction of marine life. If the carbon emission continues to grow, our oceans are at risk of turning more acidic. Since the industrial revolution, our oceans have reduced from pH level 8.2 to pH level 8.1 i.e. by 0.11 unit, in the past two centuries. This may look like a tiny change but a further reduction in pH level could have a detrimental effect on our marine friends. Acidification would mean more production of nitrous oxide gas too, which is also a greenhouse gas and has been known to deplete the ozone layer. In the Pacific region, the pH has been decreasing at a current rate of 0.0051 units per year and if it continues to fall in the same rate, the rate of nitrous oxide would increase to 491 per cent by the year 2100 from current 185 per cent. Greenhouse effect caused by nitrous oxide is 298 times more than that of carbon dioxide.
Ocean acidification is just one ramification of increasing carbon emission, among many climate changes implications. There is a need to monitor and research ocean acidification impact on marine life and prepare our estuaries and coastal communities which majorly depend on such shelled animals. If we want to reduce carbon emission, we will have to eliminate fossil fuel combustion; reducing our meat consumption, switching to cleaner energy are some other steps in the right direction to tackle ocean acidification and check a total collapse of the marine ecosystem.