Activity - Climate Change and Ocean Acidification

By Brittany Ahmann, Environmental Educator, Sea Smart 

The learning concepts of this activity are best suited for late elementary or early secondary age children, but the activity itself can be fun for any ocean or chemistry enthusiast. 

Did you know?

Not only does our ocean produce oxygen, but it also acts as a carbon sink. As carbon dioxide levels increase in our atmosphere, there is more carbon dioxide dissolving into the ocean. When carbon dioxide mixes with water molecules, it causes a chemical reaction resulting in the production of carbonic acid. 

Chemical equation of the reaction between carbon dioxide and water. Note that this reaction can also go in the other direction.

This carbonic acid is causing our oceans to become increasingly acidic. Acidic oceans impact the hard calcium-based structure of animals including shells, coral exoskeletons, and even fish ear bones (otoliths) (1)! See the effects yourself of how shells are impacted by an acidifying ocean!

What will you need?

• White vinegar

• Water

• 2 jars

• Shells from the beach (please ensure there are no living animals on them and that you are not taking them from a no-take zone) Tip: If you don’t have access to shells or a beach, sidewalk chalk is a great substitute that simulates marine bicarbonate structures like shells or corals.

Ocean acidification experiment set-up

Step by step instructions:

1. Clean shells by washing them in freshwater.

2. Fill 1 jar with sea water and one with vinegar.

3. Have the kids make their hypothesis: what do they think will happen to each shell?

4. Add a shell to each jar.

5. Watch what happens!

6. Let shells sit in solution for ~1 week.

7. Remove and rinse shells.

8. Compare the differences.

What’s happening?

When the shell is added to the water nothing should happen, but when shells are added to the vinegar you’ll probably notice the bubbling that occurs right away! This is because the acid reacts with the calcium in the shell. Over time the shell will actually begin dissolving and may even dissolve completely if left long enough. After letting the shells soak for a week, compare the strength of the shells. You will probably notice the shell from the seawater is still very strong, as it should be, but the shell from the vinegar is brittle and easy to break.

Super Scientist Extension: Have your kids determine the following components of this experiment: 

• Control (base experiment used as a comparison with other trials of the experiment)

• Independent variable (part of the experiment the scientist changes)

• Dependent variable (part of the experiment that reacts to the independent variable) 

The impacts of ocean acidification

Why this matters:

Ocean acidification is a growing concern for the ocean in the face of climate change (1). Brainstorm ways you and your family can reduce your impact on climate change and ocean acidification!

Liked this experiment?

Show us your experiments on social media and check out our other marine biology activities to do during school closures!

Bibliography

1. NOAA. (2013). Ocean Acidification. National Oceanic and Atmospheric Administration. https://www.noaa.gov/education/resource-collections/ocean-coasts-education-resources/ocean-acidification