What is ocean acidification? Here’s a quick answer and definition to this:

Ocean Acidification refers to the ongoing and worsening decrease in the pH of the Earths’ oceans. The pH level of the case has been falling since the beginning of the Industrial Revolution. The logarithmic pH scale informs scientists that the pH level has fallen 0.1 pH units over that time period. This represents a 30% increase in ocean acidity. 

Since the beginning of the industrial era, the ocean has absorbed 525 billion tons of CO2, around 22 million tons a day. Initially, scientists believed that this feature of the oceans was positive, something that would relieve the atmosphere of greater amounts of carbon dioxide and slow down the warming of the planet.

But, as studies have progressed, they have realized that this comes at a weighty cost to the balance of ocean ecosystems. The changes have been occurring so quickly, “faster than any known change in ocean chemistry in the last 50 million years.” This means that organisms have not had time to keep up. They haven’t been able to adapt to the increased acidity and decrease pH that makes up their habitats.

This is how Ocean Acidification works
This is how Ocean Acidification works

The pH Scale Explained

The pH scale ranges from 0 to 14, with the mid-point, 7, being neutral. Numbers higher than seven are considered “basic” or alkaline, while numbers lower than seven are “acidic.” When the pH number goes down, the acidity goes up. More hydrogen ions means higher acidity and a lower pH.

Today, the ocean’s average pH is around 8.1, which is basic. Scientists estimate that by the end of the 21st century, the ocean could have a pH level of 7.8. 

What Causes Ocean Acidification? 

Ocean acidification is caused by the decrease in the pH level of the ocean. This is set in motion when the ocean absorbs more CO2 than it can process. Chemical reactions occur that increase the acidity of the water. The majority of this change can be set at the feet of humankind, the burning of fossil fuels, and changes in land use. The ocean is responsible for absorbing 30 percent of the Co2 released into the atmosphere, so when that amount increases, so too does the percentage that the oceans take in. The seawater takes in the CO2, and subsequent chemical reactions occur that result in more hydrogen ions. This increase means that the seawater’s acidity rises, and carbonate ions decrease. 

Effects of Ocean Acidification 

Scientists know that over time the pH levels of the oceans are going to decrease further, leading to an overall increase in ocean acidification. Some estimates suggest that by the end of the century, acid levels could be 150 percent higher. This would lead to an ocean pH level that hasn’t existed for more than 20 million years. When it did, the ocean was several degrees warmer and in the middle of a major extinction event. Ocean acidification is leading to the destruction of important calcium carbonate minerals that many sea creatures need to build their skeletons and shells. 

Impact on Marine Animals 

There are wide-ranging implications in regard to the increasing acidity levels of the ocean over time. One of the most prominent is the impact on biological organisms. There are some plants, such as algae and seagrass, that might benefit from the change, but others, including oysters, clams, and corals, would be negatively impacted by increasing CO2 levels. So far, increasing carbon has proven to decrease corals’ ability to produce their skeletons. It also compromises fertility in the ocean and impacts the coral’s ability to recover from a variety of disturbances. A new study suggests that by 2080 the ocean will be so acidic that coral reefs will disappear more quickly than they’re able to rebuild. 

Bleached coral Acoropora
Bleached coral Acoropora

In regards to shellfish, scientists have noted larval oyster failures that are connected to increases in the pH level of the ocean. The oyster industry is incredibly important, but only one of many ocean-based industries that would be disrupted by further rises in acidification. Another interesting study was done on pteropods, also known as the “sea butterfly.” This very small sea creature’s shell was determined to dissolve in low pH level waters over a period of 45 days. 

These changes also have an impact on leading marine animals as well, such as fish, which suffer from a decreased ability to detect predators in more acidic waters. Other studies have shown that larval clownfish struggle to find suitable habitats in more acidic waters. As a crucial part of the food chain, the entire marine ecosystem falls into danger. 

Broader Economic Impact 

When the ocean’s ecosystem is threatened, so too are the livelihoods of millions of people who depend on the ocean for their own substance and for their employment. Coast estuaries and waterways are affected as well, meaning that as the problem increases, it’s going to be harder and harder to avoid. Incredibly important parts of the fishing industry are in danger, such as the American lobster, scallops, and red king crab.


Great Barrier Reef, Australia
Great Barrier Reef, Australia

What Solutions are there to Stop Ocean Acidification? 

Ocean acidification is just one of the many negative impacts of the global climate crisis. It, like the broader warming of the planet and the melting of glaciers, is the fault of humans-created fossil fuels. Anything that humanity does to stop or mitigate climate change is going to benefit the ocean. 

Luckily, an increased focus on this problem by groups such as NOAA’s Ocean Acidification Program is forging relationships between scientists, the public, and governmental officials in order to monitor the changes in ocean chemistry. Now that the impacts of ocean acidification are being closely monitored, to more likely that enough can be done in time to stop a total collapse of marine ecosystems. NOAA notes that it is impossible at this time, due to the early stages of their research, to truly know what exactly ocean acidification is going to result in. 

NOAA encourages educators to include lessons on ocean acidification alongside this about the food web and the broader interconnectivity of ocean, and the world, ecosystems. 

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