The World's Largest Carbon Sink:
What Is Up With Ocean Acidification?

What Exactly is Ocean Acidification?

Ocean acidification refers to a reduction in the pH (so more acid) of the ocean over an extended period of time, caused primarily by uptake of carbon dioxide (CO2) from the atmosphere.

Also see further information on Wikipedia:

So How Does Ocean Acidification Happen?

How Does the Current Trend Look Like?

PH outlook for 2100

(move the line to see the pH development)

Changes by 2100 vs 1800

(move the line to see the pH development)​

According to economic models, the ocean pH level could reach a level below 7.8 by 2100. Gattuso et al (2014) simulated two scenarios with reduced green gas emissions (RCP2.6) and large green gas emissions (RCP8.5). the RCP8.5 scenario exhibits a shocking forecast to 2100. See the original research paper.

Why Is This A Problem?

Who is effected?

Some examples of the impact

(click on each for further details)

Pteropods are tiny marine creatures but they are largery connected to the food chain in the ocean as they provide food for many creatures. Acid water dissolves their shells rpidly causing them to disappear or reduce in size. See what happens to their shell in just 45 days in water with a pH level of 7.8 (2100 expected).


The protective shell of shellfish (e.g. crabs, mollusks) are made of calcium carbonate. When there is an abundanceof CO2, hydrogen ions are bonding with carbonate ions meaning it takes carbonate away from these creatures. It makes it harder to regenerate and build their shell meaning they spend more energy on the process. As a result, they spend less time on reproducing (less) and eating (smaller).


Fish are impacted in 3 major ways. 1. Given the smaller size of Shellfish and Pteropods, they have less food meaning they are likely to grow smaller. 2. They need to expel any excess acid through their gills, kidneys, and intestines. This process takes precious energy could have been used to digest food or escape predators. 3. More acid waters impair some of their senses making them more vunerable against predators. All three results a decrease in both number of fish and the size of them.


Coral reefs re also composed of calcium carbonate. They use it to build their “hard skeleton”. This is especially true in the early stages of development. With more carbonate ions bonding with hydrogen ions, that means less carbonate ions available for coral reefs. This results difficulties in reproducing and developing of the coral reef effecting all the creatures living in them.

As the foodchain in the ocean collapses, this impacts humans and the whole world. 15% of protein intake of people comes from the ocean and oceans have a massive impact in other areas of the everyday life too. For example, planktons conduct photosynthesis and have a significant share in oxigen creation in the world.

Accordion Content

For the reasons described on the left hand side, the average size of fish is expected to decline by c.24% by 2050 causing significant issues in the foodchain.

Shrink in Body Weight (by 2050)

D. Liittschwager made a photo series of a Pteropod shell, placed in pH 7.8 (pess. estimates by 2100) seawater. In 45 days the shell disappeared.

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