Ocean Acidification Causes and Effects: A Comprehensive Guide

The issue of ocean acidification is not new. We have covered it before, especially when it came to its relationship with coral reefs’ damage and marine wildlife endangerment. However, the problem needs a closer look and our undivided attention. The ocean acidification causes and effects concern us all. Today, we will offer you a comprehensive guide on this extremely serious issue.

What is Ocean Acidification?

Dubbed “climate change’s equally evil twin,” ocean acidification means that there is too much carbon dioxide dissolved in the ocean. In fact, according to recent statistics, since the beginning of the industrial era, the ocean has absorbed some 525 billion tons of CO2 from the atmosphere, presently around 22 million tons per day. But how does this happen?

One can argue that CO2 is essential for life and it is not as if humans invented it. It is naturally occurring element in the air and plants need it to grow. The problem is that because we burn fuels, there is now more carbon dioxide in the atmosphere than any time in the past 15 million years.

The excess carbon dioxide in our air does not remain in the atmosphere but dissolves in seawater. It seems that the ocean absorbs around one-quarter of the total atmospheric CO2 derived from burning fossil fuels and land use changes. The CO2 dissolves in seawater and forms carbonic acid. As we emit more and more CO2 into the atmosphere, the ocean absorbs greater amounts at increasingly fast rates. This process is altering the ecosystem’s ability to adjust to changes in CO2 that would naturally occur over the millennia, thus significantly changing the chemistry of the seas, and leading to progressive acidification.

If you were interested in the ocean acidification causes and effects, this is the “causes” part lit and clear. We change the oceans’ chemical composition by overusing fossil fuels and emitting massive amounts of CO2 into the atmosphere.

It seemed a Good Thing at First…

Upon the discovery that the oceans absorb CO2 from the air, scientists initially believed it was a good thing. The process would leave less carbon dioxide in the air, thus reducing atmosphere warming. However, in the past decade, no scientist could ignore the evidence any longer. While the CO2 dissolved in water does prevent even more planet warming, it also changes the chemistry of the oceans with unpredictable consequences. According to collected data, in the past 200 years alone, ocean water has become 30% more acidic. This is a rate of change roughly 10 times faster than any time in the last 55 million years.

In the past, scientists gave this problem little thought. For many years they assumed that the rivers would carry enough dissolved chemicals from rocks to the ocean to keep the ocean’s pH stable. This is the buffering effect you may have already know about. However, there is too much CO2 dissolving in the ocean very fast and the natural buffering effect cannot keep up. As a consequence, the seawaters’ pH registered rapid dropping. The surface layers of the oceans’ water gradually mix into deep water, so the oceans’ bodies of water begin to suffer.

A Few Words on pH

The pH is a measure of acidity or alkalinity. A pH below 7 is considered acidic, and a pH greater than 7 is considered alkaline, or basic. Since 1850, the average pH of ocean surface waters has fallen by about 0.1 units; from 8.2 to 8.1.

Today, scientists consider that the average ocean water’s pH is currently 8.1. However, the pH scale is logarithmic, so a one-point change on the scale means a tenfold change in concentration. In other words, we currently witness a roughly 30% increase in ocean acidity, as we mentioned above.

Causes and Mechanisms of Ocean Acidification

To sum things up, ocean acidification occurs as follows: we release CO2 in the atmosphere – about ¼ of the carbon dioxide ends up in the oceans – the seawaters’ pH drops, turning the water more acidic.

The main issue here is that the process occurs at a very fast pace. There is just too much CO2 getting in the waters at high speeds, rapidly changing the chemistry of the deep waters.

In other words, the quick changes in ocean chemistry do not offer marine life a generally stable pH or enough time to adapt.

While it’s true that some marine organisms are finding ways to adapt, other species and entire ecosystems are fighting for their life.

The mechanism is easy to understand in its entire severity if you consider the following aspects:

  1. The pH of seawater water gets lower as it becomes more acidic.
  2. This process binds up carbonate ions and makes them less abundant. Ions that corals, oysters, mussels, and many other shelled organisms need to build shells and skeletons.

Ocean Acidification Effects

As you can clearly figure out, the biological impact of ocean acidification is incalculable yet. We can predict the chemistry, but we cannot still coin in detail how things will look in the future. The warnings are grim, however.

As we reported, experiments show that if we do not do something about global warming, the oceans may become too acidic and endanger coral reefs past the point of return. It is true, however, that some organisms may thrive in more acidic conditions while others will struggle to adapt or even go extinct.

Beyond the fact that we endanger marine ecosystems and biodiversity, we also encourage other damages linked to the acidification of oceans. Ocean acidification will affect human activity and human life in its entirety:

  • A threat to fisheries and aquaculture, leading to food insecurity of millions of people
  • A threat to all sea-related economies, including tourism
  • A threat to coral reefs and coral reef sands as they dissolve in contact with the acid water
  • A threat to the production of the oxygen we, the plants, and the animals need for survival
  • A threat to the creation of clouds that help shade the planet
  • A threat to the entire food chain, including us
  • A threat to shoreline protection.

How Bad Are and Will Things Be?

We know that the oceans’ pH has dropped from 8.2 to 8.1 since the industrial revolution. The problem is that if we go with the business, as usual, we can expect the oceans’ pH to drop by another 0.3 to 0.4 pH units by the end of the century.

If we continue to release carbon dioxide at present rates in the future, seawater pH may drop another 120% by the end of this century, to 7.8 or 7.7. This would an ocean more acidic than anything we have seen for the past 20 million years or more.

The smallest change in the pH of seawater can have destructive effects on marine life. It disrupts chemical communication of the organisms, affects reproduction, and growth forces fast adaptation that may lead to mutations or extinction.

A drop in blood pH in humans of no more than 0.2-0.3 units can cause comas, seizures, and even death. Imagine what such falls can do to corals, marine wildlife, algae, and so on.


We will leave you today with a conclusion drawn by the scientists publishing the document Ocean Acidification: The Facts. A special introductory guide for policy advisers and decision makers: “Ocean acidification is taking us on an uncharted voyage and we only have a few hints about how many of these essential processes will be impacted.

Ocean acidification must be recognized for what it is: a global challenge of unprecedented scale and importance that requires immediate action to halt the trend of increasing acidification. There are no practical solutions to remediate ocean acidification once it has occurred. We may have to rely on nature to take its course. This will inevitably be a long-term recovery process that could take upwards of 10,000s of years for the ocean to be restored to its carbonate equilibrium. Biological recovery could take perhaps even longer.

This can only be done through a real, sustained and substantial reduction in emissions to stabilize atmospheric CO2 levels, through cuts in what we emit and by technology that actively removes CO2.

Image sources: 1

Show Your Friends!
William E. Eubanks

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

Click Here to Leave a Comment Below 1 comments