What is ocean acidification?

Lesson overview

An introduction to the issue of ocean acidification, this lesson uses a combination of video, theory and practical demonstrations to develop students’ understanding of the ‘other carbon problem’.

Learning outcomes

  • Recall that the release of CO2 by burning fossil fuels increases the level of atmospheric CO2
  • Understand the process of ocean acidification and that the oceans act as a ‘carbon sink’ for atmospheric CO2
  • Investigate the impact of increased levels of atmospheric CO2 on ocean chemistry

Lesson steps

  1. The hidden problem (10 mins)
    Introduce students to the ‘other carbon problem’ by showing them the Acid Test 3 minute video (see ‘Lesson resources’). Discuss with students:
    How does carbon enter the atmosphere?
    What happens when carbon dioxide is absorbed into the oceans?
    How much has ocean acidity increased since the Industrial Revolution?
    What effect does ocean acidification have on marine organisms?
    How can the impact of ocean acidification be lessened?
  2. How does ocean acidification happen? (10 mins)
    Use the slideshow to explain the process of acidification.
  3. Why are the oceans becoming more acidic? (25 mins)
    Use the slideshow to remind pupils of the pH scale and demonstrate the effects of increased atmospheric carbon dioxide.
    Students will look at the difference between the pH of seawater and freshwater as more carbon dioxide is added.
    Science technicians may be able to help with relevant equipment, including pH indicator solution or pH meter.
  4. Plenary discussion (5 mins)
    Ask students to review their learning and to make connections to prior learning in both science and geography:
    One thing that surprised them;
    An item of prior knowledge that they used;
    Something that they learnt.