What Causes Ocean Acidification? 7 Main Causes

Human economic activities – growing food, extracting raw materials, manufacturing goods and disposing of wastes – help to maintain a comfortable standard of living in the Western world. Yet, if the issue of climate change is any indicator, these enterprises also yield detrimental side-effects for the environment. For a time, such harmful byproduct posed little threat to the oceans, the vastness of which seemed well-suited to robustly capture excess carbon. Scientific observations, however, demonstrate a disturbing change in oceanic constitutions because of carbon glut.

Eliminating the Carbonate Ions

Of the entire emission of carbon dioxide (CO2) into the atmosphere annually, 25 percent finds its way to the world’s seas. Yet this absorption is far from benign. Receiving about 30 percent of the CO2 from the air, the surface water undergoes a sequence of chemical changes whereby its hydrogen ions become more heavily concentrated. Thus the pH (potential hydrogen) levels in the water diminish, making the ocean more acidic.

What causes ocean acidification also inhibits carbonate ions, essential components in shell fish and coral. Those organisms living in acidic seas demonstrate significant erosion in shell structure and skeletal soundness. This buttresses the argument that acidification is not just a measurement, but an existential threat.

ocean acidification comic

Burning of Fossil Fuels

A reliable rule of thumb is that when C02 emissions increase in the atmosphere, so too does CO2 presence expand in the oceans. What causes ocean acidification is what causes global warming – at least in part. The burning of fossil fuels – i.e. petroleum, coal, natural gas – causes solar heat that would normally be deflected back toward space to remain within Earth’s atmosphere.

The gases emitted from fossil fuels, CO2 among them, block the heat from its celestial destination. As noted above, nearly a third of the CO2 gets absorbed by the oceans.

Manufacturing Concrete

The process that go into making concrete yield a surprising amount of atmospheric CO2. For every ton of cement composing structural (for use in buildings, roads, bridges etc.) concrete, 900kg of CO2 escape into the atmosphere.

This is because the cement component of concrete must be heated to over 2,700 degrees Fahrenheit for the necessary lumps and nodules (also known as “clinker”) to develop in the mix. Alite, the mineral responsible for the strength of concrete, demands this intensity of heat to establish itself with optimal properties.

Research and development of non-cement-based concrete products is ongoing, and showing much promise.

worker leveling concrete

Land Use Evolution

As development encroaches on natural habitats, the elimination of forests, grasslands and other natural “sinks” for CO2 mean more of the gas in the air…and in the seas. Natural vegetation serves as food source and protective cover for many different species of fauna. It also, however, absorbs CO2, removing it from the troposphere. When such flora is plowed under or otherwise degraded for development, commerce and residences, the ecosystem loses an important component in the regulation of greenhouse gases like CO2. Even when the displacement occurs hundreds of miles from coastal regions, it is still a culprit in what causes ocean acidification.

Disposal of Waste

Coastal nations the world over have used the oceans as deposits for waste. Sewage – especially when improperly treated – contains compounds that contribute to a rise in acidity. In addition, agricultural and industrial wastes also harbor materials that tend to lower the pH of water. Wastewater should maintain an alkalinity between six and nine (on a scale where 0 is most acidic and 14 is most alkaline). Unfortunately, much of it is below six.

Since there are few enforceable international standards, some nation-states allow a greater measure of solvents, cleaners and grease in the wastewater emancipated into the sea. The condition of marine life may have to suffer further before countries can agree on a waste management protocol.

sewage dumping in the ocean, one of the causes of acidification

Natural Ionization of Ocean Water

As noted, the generation of hydrogen ions is a vehicle for what causes ocean acidification. Although many causes relate to human activity on the planet, there are chemical reactions occurring undersea that are catalysts in hydrogen ion production.

Metabolic processes and aerobic respiration in and among sub-surface organisms always release some hydrogen ions. Accordingly, some acidification will always be present in major bodies of water. No, by themselves, these organic activities will not drive overall pH down to levels of dangerous acidity. Still, they make a contribution.

Manufacturing and Acid Rain

The manufacturing and processing industries employ plants and factories that release compounds like nitrogen oxide and sulfur dioxide into the air where they combine with oxygen, water and myriad other gases. These combinations will return to the Earth in the form of acid rain (…and sleet and fog and snow). Acid rain falls on soil, life forms, rivers and streams. The oceans, by the way, are not immune. Sources of the compounds are also vehicles like cars, trucks and buses criss-crossing the nations by the million.

Acid rain can fall on oceans directly or travel through tributaries and rivers. Indeed, it often originates in metropolitan areas and migrates to outlying areas. Whatever the mode of arrival, it adds to the acidity of oceans and the resulting ecological harm. It counts – at least modestly – among what causes ocean acidification.

Industry, demonstrably, is implicated in each of the causes listed above. The good news is that the industrial ingenuity that produced assembly lines and smokestacks is now developing new filters and scrubbers to reduce toxic emissions; substitute materials for cement and petroleum; and new methods of treating sewage and other forms of waste. While ocean acidification is a big problem now, we are not necessarily stuck with it.

Final Thoughts

Acid is a corrosive substance that – while enjoying many practical uses on shore – threatens life under the sea. Unfortunately, the oceans do not exist in isolation: atmospheric conditions impact maritime conditions. It stands to reason, then, that mitigating any one of these causes is helpful, but not sufficient. Ultimately, a comprehensive environmental solution must address the problem on land, in the air and at sea. All of us can start somewhere.

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