Carbon Cycle in the Ocean


A global cycle represents the path of an element as it moves through the spheres of the Earth – the biosphere, lithosphere, hydrosphere and atmosphere.  An example of this is the carbon cycle.

The ocean is an important carbon sink, absorbing more than 30% of atmospheric carbon dioxide each year. A carbon molecule can remain trapped in the ocean lithosphere for thousands of years or can move rapidly through the marine environment, as carbon dioxide for photosynthesis.

As the amount of atmospheric carbon dioxide increases, the amount held within the ocean also increases. The carbon dioxide combines with water, forming carbonic acid. In excess, this can cause ocean acidification, impacting on the marine ecosystem and contributing to issues such as coral bleaching.  

Coral Bleaching

Carbon dioxide uptake by water plants

Conduct a simple test to show how carbon dioxide uptake by water plants reduces the acidity of water. Our video The Carbon Cycle and Our Oceans demonstrates one method to do this.

How can we apply this to reduce the amount of carbon in our oceans?


Where to now?

  • Research further information about the carbon cycle and investigate more activities at WASP.
  • Make your own pH indicator using red cabbage, demonstrated in our video Carbon Dioxide and pH of Water.
  • Learn more about the impacts of increasing acidity in our oceans in our video Ocean Acidification and at the National Oceanic and Atmospheric Administration (NOAA).
  • Find out more about establishing seaweed forests in our oceans at Cool Australia.
  • Take action on climate change. Some ideas to get you started are in this AusEarthEd video Climate Change: Take Action.