Disasters At Sea: Ocean Acidification
- The Persaud Foundation
- 1 day ago
- 5 min read
Introduction
In the 200 years since the Industrial Revolution began, humanity has been rapidly releasing carbon dioxide into the atmosphere — but it doesn’t always stay there. Our oceans absorb 30% of the carbon dioxide added to the atmosphere, and it’s changing the chemistry of the water through a process known as ocean acidification. In this article, we’ll describe exactly how ocean acidification occurs, its impacts on marine life, and what solutions are underway.
The Disaster: Ocean Acidification
Carbon is stored in the air, the ground, vegetation, and the ocean. When we burn fossil fuels, we’re taking carbon from underground and releasing it into the air. When we cut down forests, we release the carbon stored in those trees back into the atmosphere. In essence, human activity has been shifting CO2 concentrations away from carbon sinks (systems that absorb carbon from the atmosphere) and back towards the atmosphere instead.
As we have released more and more carbon dioxide, our atmospheric CO2 concentration has increased dramatically. A lot of that carbon dioxide stays in the atmosphere where it traps heat and contributes to global warming. However, almost a third of it dissolves into the ocean, our largest carbon sink. In fact, since the Industrial Revolution in the 1700s, our oceans have absorbed 525 billion tons of CO2 from the atmosphere. Today the oceans are absorbing 22 million tons per day.
Without carbon sinks, our atmosphere would have even more CO2 than it currently does and our planet would be warming even faster than it already is. By taking so much of our excess carbon dioxide out of the atmosphere, the oceans have slowed the rise in global temperatures, but it has come at a cost.
The excess CO2 in our oceans is now changing the chemistry of the water and making it more acidic. To better understand the process of ocean acidification, we need to break down this chemistry.
Acidity is determined based on the presence of H+ ions. The higher the concentration of H+ ions, the more acidic something is. The pH scale is used to measure acidity where a zero on the scale is very acidic, a 14 is very basic, and a 7 is true neutral.
In our oceans, when carbon dioxide (CO2) dissolves in water (H2O), carbonic acid (H2CO3) forms. An acid is a substance that releases H+ ions, so by nature, the presence of carbonic acid increases the presence of H+ ions in the water thereby making it more acidic. As such, an increase in carbon dioxide directly increases the ocean’s acidity by producing more carbonic acid that releases more H+ ions.
On the pH scale, the ocean’s average score has fallen 0.1 units, from 8.2 during pre-Industrial times, to 8.1 today. Though this may not seem like a large drop, this slight shift toward the acidic end of the scale has significant implications for marine life.
Impacts
Ocean acidification is occurring far too quickly for marine organisms to adapt. The chemistry of seawater affects the daily living, growth, and reproduction of marine organisms, so even this small change in water acidity has big repercussions.
Animals that build shells and skeletons are particularly affected by ocean acidification because they rely on chemicals in ocean water to build those structures — chemicals that are now depleted by ocean acidification.
Oysters, clams, snails, crabs, lobsters, and corals are just some of the animals that build their shells/skeletons by using the calcium ions and carbonate molecules naturally present in seawater. These two chemicals combine to form the animal’s calcium carbonate structures (shells/skeletons). However, H+ ions also bond to carbonate and have a stronger attraction to carbonate than calcium ions. As such, the increased presence of H+ ions in today’s more acidic seawater decreases the availability of carbonate for calcium carbonate structure building. The H+ ions essentially “steal” carbonate away before calcium ions can bond to form shells/skeletons.
Not only do H+ ions get in the way of building calcium carbonate structures, but if there are enough H+ ions present in the water, they can actually begin to break down shells/skeletons that are already built. Therefore, ocean acidification makes it harder for animals to build their calcium carbonate structures and easier for those structures to break apart once built.
Ocean acidification can also hurt larvae, as larvae are small and therefore more vulnerable to changes in acidity. This can cause issues with development and the ability to reach a healthy adulthood.
On the other hand, the increase in carbon dioxide in our ocean may encourage plant and algae growth, as these species rely on CO2 for photosynthesis. More acidic conditions have been shown to increase growth and reproduction for seagrasses. However, there are other stressors (such as pollution) hurting these populations more than acidification is likely to help them.
It is therefore increasingly important to address the root cause and impacts of ocean acidification going forward to maintain healthy conditions for marine life.
Recovery
The most important solution for slowing ocean acidification is to decrease carbon emissions. The less CO2 we add to the atmosphere, the less CO2 will end up in our oceans, and the less acidic our seawater will become.
Our seawater is already too acidic though, and our atmosphere is already too polluted with CO2. In order to truly reduce the impacts of ocean acidification, we need not only to limit our future emissions, but also to remedy our past emissions by removing the excess CO2 currently in the air.
There are two main ways to do so: 1) preserving and increasing natural carbon sinks, and 2) implementing man-made carbon capture and storage. The ocean is our largest natural carbon sink, but there is great potential for other systems to absorb more carbon dioxide as well. For example, forests and vegetation hold massive carbon sequestration potential. Protecting old growth forests, mangroves, and other plant ecosystems can help decrease CO2 concentrations in the atmosphere. While deforestation and wildfires release all the carbon previously stored in these carbon sinks, reforestation and conservation efforts can preserve and expand their ability to remove carbon from the air.
Man-made carbon capture and storage is a technology that works by filtering carbon out of the atmosphere and storing it underground. This is often done at the site of CO2 sources such as power plants. Utilizing this technology to help remove carbon from the atmosphere can help decrease CO2 concentrations and slow ocean acidification.
Conclusion
Ocean acidification is a direct result of human activities that increase CO2 in the atmosphere. The ocean, our largest carbon sink, has been absorbing that carbon dioxide and slowing global warming. However, it has come at the cost of marine life. A more acidic ocean hurts animals with calcium carbonate structures and damages many species development at the larvae stage. In the coming decades, we will need to prioritize our natural carbon sinks and focus on removing carbon already present in the atmosphere. Doing so will slow the rate of acidification and help maintain healthy seawater for marine life to flourish in.
Citations / Directories
Citation No. 1: “Ocean Acidification”, Written by Unknown, Published on September 25th, 2025. Published by NOAA. Retrieval Date: May 28th, 2026. https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification
Citation No. 2: “Ocean Acidification", Written by The Ocean Portal Team, Published on Unknown Date. Published by Smithsonian National Museum of Natural History. Retrieval Date: May 29th, 2026. https://ocean.si.edu/ocean-life/invertebrates/ocean-acidification
Citation No. 3: “Effects of Ocean and Coastal Acidification on Marine Life,” Written by Unknown, Published on April 21, 2026. Published by the EPA. Retrieval Date: June 1st, 2026. https://www.epa.gov/ocean-acidification/effects-ocean-and-coastal-acidification-marine-life
Citation No. 4: “Shell Dissolves in Seawater”, Written by Unknown, Published in April 2015. Published by Smithsonian National Museum of Natural History. Retrieval Date: June 1st, 2026. https://ocean.si.edu/planet-ocean/temperature-chemistry/shell-dissolves-seawater
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