Ocean Acidification | Causes, Effects and Solution

Ocean Acidification

There is a misconception among the population that all human-made carbon dioxide emissions go into the air and contribute to global warming, climate change, rising oceans, and melting glaciers. In reality, 30% of all human-made CO2 emissions are absorbed by the ocean’s surface and then slowly mixed down into the water column, which in turn decreases pH levels and makes the ocean more acidic as a result.

Ocean acidification is the change in the ocean’s chemistry due to a decrease in pH levels within the surface. This decrease in pH is causing the ocean to become more acidic due to long-term CO2 absorption.

The ocean has been absorbing CO2 from the atmosphere at a rapid pace since the beginning of the industrial era. Currently, it is absorbing it at a rate of roughly 22 million tons per day for a total of 525 billion tons in the past few decades. Keep reading to learn more about ocean acidification and its effects on the planet.


What is Ocean Acidification?

Ocean acidification is the significant and harmful excess of carbon dioxide in the atmosphere that is not as readily noticed due to being absorbed by the ocean. This, in turn, causes the pH levels to decrease in the water, which is rapidly making the water itself more acidic.

Approximately 30% of the CO2 released into the air from human-made emissions such as burning coal, oil, and gas finds its way into the ocean, where it then mixes with the water and pushes itself deeper into the water column.


Is This the First Time the Ocean Became More Acidic?

The ocean takes up the majority of the planet and helps absorb carbon dioxide. This phenomenon was first noticed over 30 years ago. However, scientists mistakenly thought that it was not going to cause long-term harm due to the minerals and run-offs of rivers and streams.

However, in 2003, it was discovered that the ocean’s pH had decreased to 8.1 from the previous 8.2 readings, and thus the term “ocean acidification” was coined.

However, like most things, history repeats itself even with ocean acidification. The last known acidification happened approximately 80 thousand years ago. Unfortunately, the pH is decreasing at such a rapid speed and is worsening up to the point of the previous great acidification that happened nearly 55 million years ago, resulting in one of the Earth’s mass extinction events.

This rapid change in the acidity of the ocean is a frightening development. If not corrected, scientists are concerned about the very real possibility of another mass extinction event within the next few centuries.


Ocean Acidification’s Impact on Marine Life

Due to the fact that the ocean’s natural buffering system of taking in minerals and freshwater from streams, rivers, and other bodies of water isn’t keeping up with the extreme levels of CO2 being absorbed into the ocean, much of the marine life is already feeling the effects of the more acidic water.

Coral Reefs

Coral reefs are created from calcium carbonate and house a massively diverse ecosystem for coral, fish, and numerous other organisms.

The acidification of the ocean is found to limit coral reef growth due to the corrosion of pre-existing skeletons, and slowing the growth of new corals.

The result of this is that the reefs will be more vulnerable to erosion from heavy waves and coral pickers while also being unable to rebuild themselves faster than the acidity is corroding them.

Granted, not every species of coral is in as much danger as the one next to it. Some corals can use bicarbonate to build their skeletons, and others can survive without a skeleton just fine until water parameters return to something more tolerable.

Additionally, the pH levels do not seem to be affecting the corals at the larval stage, though higher acidity does seem to stop them from finding a place to settle and thus reaching adulthood.


Fish, like people, are sensitive to changes in pH levels. In order to keep its body balanced at appropriate levels, a fish has to work harder and burn extra energy to remove these levels from its gills, kidneys, and intestines. This makes it harder for the fish to escape predators, build homes, reproduce, grow, or even digest their food.

Higher acidity levels have also been found to alter how their brains process, such as making them not notice noisy predators. It also has been proven to cause certain fish to grow a larger otolith bone which can affect their balance and navigation.

Plants and Algae

Plants and algae may be the best forms of life equipped to handle the change in pH levels, as aquatic plants thrive on combining sunlight with carbon dioxide.

Therefore, it does not hurt most of them to be in water that is more acidic. In fact, it’s also proving to allow these hardier species to grow taller and with deeper roots. Plants and algae typically are facing more dangers in the form of run-off pollutants.

However, there is an issue with coralline algae, which is the algae that helps cement coral reefs. This kind of algae has a more soluble shell. It will cover 92% less area in environments with higher acidity, which gives room for non-calcifying algae to move in and smother available space.

Additionally, when coral larvae are trying to settle, they will try to settle on coralline algae to start life and build the reef.

Shelled Animals

Shelled animals, such as mussels, clams, urchins, and starfish, are already at a point where their shells are beginning to corrode due to the lowered pH levels. They are expected to slow growth by up to 25% within the next century as well, while also being more susceptible to predators due to weakened shells and shell-like parts.

Additionally, the water is getting so acidic that many of these creatures cannot even start growing their shells before they start getting corroded away, which is causing massive die-offs.

However, some studies have found that crustaceans are growing stronger shells under the higher acidity, even though some species do have difficulties digesting food during larval stages at high acid levels.


Zooplanktons are very tiny drifting animals that build their shells out of the easily corroded calcium carbonate. These creatures are at the very bottom of the food chain and are so critical to the carbon cycle. As they die, they sink to the seafloor, where their shells are deposited as rock and sediment and help slow the rise of global warming.

Even though these creatures reproduce rapidly and are relatively quick to adapt, they are also rapidly dissolving in the currently high acidity levels. This has some studies believing that entire species are going to be extinct by the end of the century.


Chemistry of Ocean Acidification

Liquid acidity is based on the number of hydrogen ions it has, with the more acidic liquids having more H+ than more alkaline liquids. When CO2 is absorbed into the ocean water, it combines with the water molecules to create carbonic acid, which then breaks apart into H+ and bicarbonate ions, which causes the water to become more acidic.

Seawater has a natural average pH of 8.2 because it contains natural alkaline ions from the weathering of continental rocks, which are then brought to the oceans via streams, rivers, and other flowing bodies of water. The ocean’s surface absorbs CO2 from the atmosphere, with 30% of all human-made emissions going straight to the ocean. This is then mixed into the water and goes deeper into the water column.

Since the beginning of the industrial era, the average pH has fallen to approximately 8.1. It is important to note that pH is logarithmic, meaning that a change of 1 pH unit represents a tenfold change in acidity.

Therefore, this .1 drop in acidity means that there has been approximately a 26% increase in acidity in the past few centuries. This is a rate that is 100 times faster than has been recorded in the past 80 thousand years and is reaching a level at such a high rate it is starting to rival a great acidification mass extinction event that happened approximately 55 million years ago.

If it weren’t for the ocean absorbing some of the CO2 from the atmosphere, the projected atmospheric CO2 would be likely close to 475ppm. To put this into perspective, the safest level of CO2 is approximately 350ppm.

This number was reached in 1988, and it passed 400ppm in 2013. Therefore, approximately 75ppm worth of CO2 has been absorbed into the ocean, which is not doing it any favors.


What Does the Future Look Like Regarding Ocean Acidification?

The unfortunate fact of the matter is that the effects of ocean acidification and climate change are not things that can be changed quickly. The effects have a legacy that will be kept in the ocean and in the atmosphere that will be causing effects for the next few thousand years. However, this doesn’t mean that it isn’t worth trying to reduce CO2 emissions.

Lessening our carbon emissions will help prevent quicker acidification and mass extinction events by giving a little more time for plants and animals to adapt to the change in the environment. By regrowing mangroves, seagrass, and marshes, the CO2 in both the atmosphere and in the ocean would stabilize again.

Scientists have been hard at work trying to find ways to make more drastic changes in modern times to help reverse some of these effects. Geoengineering is the deliberate manipulation of planetary systems and the biosphere, and it is getting some traction.

These scientists are trying to find ways to remove CO2 from the atmosphere and ocean through various methods that may not even affect peoples’ daily lives or the quality of them at all.

Also read: Ocean Warming: Everything You Need To Know


What Can One Person Do to Help Ocean Acidification?

One of the biggest questions to hit any significant issue in the face is asking what one person can do. If it’s going to take thousands of years to fix, what’s the point? One person isn’t going to be able to do much good, are they? Mindsets like this have a negative effect on everyone and everything. Any little bit helps, as any progress is still progress, no matter how small that progress is.

Here are some ways that a single person can help slow ocean acidification, reduce CO2 emissions, and reduce their carbon footprint:

  • Recycle
  • Turn off unused lights.
  • Unplug unused devices.
  • Walk or bike short distances.
  • Carpool or use public transportation.
  • Use clean energy, including:
    • Solar
    • Geothermal
    • Wind
  • Check tire pressure.
  • Switch to alternative fuel sources.
  • Clean up beaches, forests, etc.
  • Plant trees, gardens, flowers, etc.

Even in today’s world, a major issue is that people don’t know that ocean acidification is a problem that can be addressed and helped by even just a few of us. Therefore, another way to help is to simply educate those nearby and plant the seeds for understanding at a larger scale.



Ocean acidification is the lowering of the pH levels in the water column due to increasing CO2 absorption from the atmosphere. This lowering of pH means that the water itself is becoming more acidic and corrosive, a process that is happening at a rate not recorded for many thousands of years.

Additionally, this is causing major consequences for marine life, as not all of it is capable of adapting to the extremely fast changes in the pH balance.

While there is going to be a visible effect of carbon dioxide emissions for the next few thousand years, there are still things that ordinary people can do to help reduce the rate at which the oceans absorb the CO2 in the atmosphere.

While scientists might be getting to work on geoengineering, everyday people can do things such as recycle, use alternative fuel sources, and plant trees and gardens while also educating those around them. Together, we can work to help our oceans make a gradual recovery.