Our oceans are becoming more acidic – what it means for marine life and what you can do

Oceans cover 70 percent of the earth’s surface and account for 97 percent of its water. They play a vital role in the natural carbon cycle and provides a home for over one million species of plants and animals, with another estimated nine million living in the depths left unexplored by humans. Billions of people rely on the ocean’s rich diversity of resources for survival, and its picturesque beauty provides a calming refuge and source of recreation for people around the world.

Plastic trash and other forms of pollution have turned the once pristine waters into a toxin-filled soup, but that’s not the only threat our oceans and marine life are facing. The earth’s levels of carbon dioxide, which the ocean absorbs from the atmosphere as part of the natural carbon cycle, have increased significantly. The excess carbon is lowering the pH levels of the oceans, causing acidification that is killing off coral reefs and threatening fish and other marine life.

Why it’s happening

Carbon dioxide occurs naturally in the atmosphere, but the burning of fossil fuels like coal, oil, and gas has caused levels to skyrocket. According to data from the United Stated Environmental Protection Agency, carbon emissions “have increased by about 90 percent, with emissions from fossil fuel combustion and industrial processes contributing about 78 percent of the total greenhouse gas emissions increase from 1970 to 2011.” In addition to these sources, the United Nations Food and Agriculture Organization (FAO) estimates that livestock production is responsible for 14.5 percent of global greenhouse gas emissions, while other organizations like the Worldwatch Institute have estimated it could be as much as 51 percent. In 2015, carbon dioxide was responsible for 82 percent of U.S. greenhouse emissions. Globally, it was responsible for 65 percent of greenhouse emissions in 2010.

The ocean is currently absorbing an estimated 22 million tons of carbon dioxide each day — and approximately 550 billion tons over the last 200 years — which has resulted in the water becoming 30 percent more acidic than it was before the industrial revolution. The rapidly changing pH levels are threatening the survival of species that add diversity to the ecosystem and serve as a food source for other marine life.

How acidification is affecting fish and marine life

When the pH levels of the ocean are altered, it affects several types of marine life, including coral, shellfish, plankton, and fish. Coral reefs, which are already in danger, rely on calcium carbonate to build their rock-hard structures. Acidification of the ocean bleaches coral by killing the algae in its tissue, thus making the skeletal structure less sturdy and more susceptible to damage that can kill the coral and cause it to erode.

Coral reefs are more than just beautiful structures for us to explore on a snorkeling expedition, they’re diverse ecosystems that provide a home to around 4,000 species of fish and millions of organisms, providing them shelter and protection from predators. Coral also acts as a protective barrier that helps prevent land erosion and flooding along shorelines.

Shellfish, sea urchins, and plankton also rely on calcium carbonate, which they extract from the water to build their skeletons and shells. The acidification of the oceans makes these species highly vulnerable by preventing young shellfish from developing shells and causing the shells of mature shellfish to disintegrate. Without these protective shells, they are unable to survive.

Dwindling numbers of shellfish have a direct impact on other marine species who rely on them for food, causing a chain reaction that eventually affects birds and large mammals. Without a sufficient amount of food to support an ecosystem, all species will suffer and eventually, cease to exist. A significant amount of damage has already been done, and with the ocean’s acidity expected to increase by up to 150 percent by the end of the century, it’s important to take immediate steps to prevent further damage.

What you can do

Carbon dioxide and other greenhouse gases are threatening our oceans and warming the atmosphere, resulting in changes to the climate that are placing all of us at risk.  Human actions are directly responsible for most of this destruction, but we can help prevent further damage by making a few changes to our lifestyle:

  • You can effectively halve your carbon footprint by choosing plant-based foods over meat and dairy, check out One Green Planet’s #EatForThePlanet campaign to learn more.
  • Cars are a major source of pollution, not only from emissions but because of the gas and oil they require. Try using public transportation a few times a week, or walk or use your bike for a bit of extra exercise and fresh air.
  • Reduce your energy usage by purchasing energy-efficient appliances, turning off lights when you’re not in the room, and unplugging electronics when they’re not in use. It’s a small thing that can make a big difference!

Arianna Pittman, One Green Planet, 20 July 2017. Article.

1 Response to “Our oceans are becoming more acidic – what it means for marine life and what you can do”


  1. 1 Lina Hansson 24 July 2017 at 12:57

    Note that the terminology used in this article is misleading. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7″. Despite the process of ocean acidification, the oceans are alkaline (pH higher than 7) and will not become acidic in the foreseeable future. Hence, “acid” or “acidic” should not be used when referring to seawater. Note that there are few exceptions, seawater can be acidic in the immediate vicinity of CO2 vents or in purposeful perturbation experiments.


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Ocean acidification in the IPCC AR5 WG II

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