Teacher Preparation

Overarching learning goal: By participating in this activity students will understand the role of oceans in absorbing CO₂ and how CO₂ is absorbed by sea water. Students will also recognise the impacts of ocean acidification on marine environments.

Teacher content information: Climate change is predicted to have a range of effects on our environment, some barely noticeable, others devastating. One of those predicted devastating effects is the impact on our oceans.

Carbon dioxide in the atmosphere and the oceans are exchanged at the surface layer between these two environments. When the concentration in the atmosphere increases, the ocean takes in much of it, sequestering the CO₂ from the atmosphere. In this way, the oceans are moderating the amount of greenhouse gases in the atmosphere. Without the oceans, atmospheric CO₂ levels would be even higher.

Unfortunately, this process may cause long-term damage to life in the oceans. As CO₂ is transferred into the ocean it lowers the pH and creates a more acidic environment. This already sounds pretty nasty, but when you think what it means for all those marine species whose bodies have calciferous part (molluscs, plankton, sea stars, corals and other shell inhabiting creatures), you can begin to understand why rising acidity in our oceans is being recognised as one of the most significant environmental problems we will have to face.

ACID TEST: 3 Minute Science of Ocean Acidification from Tristan Bayer on Vimeo - https://vimeo.com/8990924

For more reliable information about climate change in Australia, visit the Climate Council.

The IPCC

The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. It was created to:

provide policymakers (governments) with regular scientific updates about climate change;
highlight the impact climate change will have on the planet in the future; and,
offer some ideas about how to tackle the challenges of climate change's potential effects on the planet.

In 2021-22, the IPCC released their sixth assessment report. This is the most up-to-date physical understanding of the climate system and climate change.

The report makes a number of important points:

It is unequivocal that human influence has warmed the atmosphere, ocean and land.
Global surface temperature will continue to increase until at least mid-century under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades (B1). The report describes five possible climate futures, where #1 is not great and #5 is extremely bad. If we want to keep global warming at less than two degrees, which the IPCC says is the best-case scenario, we need to reduce our CO2 and greenhouse gas emissions significantly and start right away.

'Net zero' or 'carbon neutral' are terms that refer to achieving an overall balance between greenhouse gas emissions produced and greenhouse gas emissions taken out of the atmosphere. Getting to net zero means we can still produce some emissions, so long as we're doing something else to reduce the greenhouse gases already in the atmosphere at the same time, kind of like balancing a set of scales (more info).

Psychological safety. The IPCC Report sets a hard challenge. While this real-world issue is essential for students to understand, there is no doubt it can make them feel sad or anxious about the future is becoming darker and scarier by the day. So, reassure students that we can have a hopeful and optimistic outlook on this report, rather than one of doom and gloom. Explain that optimism involves looking objectively at a situation and making a conscious decision to focus on the good (more info), and that hope is the belief that you can make an impact (more info). Explain to students that you are going to look ahead, identify what needs to be improved, and then work on the skills and confidence so that they can go out and do it. If you're interested in learning more about how to approach challenging topics around climate change and sustainability in your classroom through a Hope and Optimism lens, consider our PD course.

Student and classroom organisation

Step 1.

Begin this activity by asking students to read the quotes from We Are the Weather Makers and watching the Acid Test clip and to respond to the relevant questions (available on the Student Worksheet). Students are asked to reflect on issues raised by the quotes and video and to answer the following questions (suggested answers provided):

Rank the following global carbon reservoirs in terms of the volume of carbon they hold:
SOIL - 2 - Vegetation and soils in the land contain about 2200 GtC.
WATER - 1 - Surface ocean contains 1000 GtC and deep ocean contains 39,000 GtC.
ATMOSPHERE - 3 - Atmosphere contains 750 Gigatons (GtC) of carbon at present.
Write a chemical equation for ocean acidification:
Once dissolved in seawater, CO₂ reacts with water, H₂O, to form carbonic acid, H₂CO₃: CO₂ + H₂O ↔ H₂CO₃. Carbonic acid dissolves rapidly to form H+ ions (an acid) and bicarbonate, HCO^3-(a base). Seawater is naturally saturated with another base, carbonate ion (CO₃⁻²) that acts like an antacid to neutralize the H+, forming more bicarbonate. The net reaction looks like this: CO₂ + H₂O + CO₃⁻²→ 2HCO^3-

Engage students in a discussion around their answers.

Step 2.

Working either independently or in small groups, ask students to create an infographic that describes the process of ocean acidification. The infographic could essentially be an illustration of the chemical reaction describing ocean acidification. The infographics should also include the causes and effects of ocean acidification. (DIY infographic background information). Below is an example of a ocean acidification infographic from the Climate Commission:

Reflection

Ask students to write two questions for a science test on oceans and carbon sinks. Questions could be TRUE/FALSE, multiple choice or short answer questions. Students could include diagrams to label or the answer could include a diagram. Ask students to be creative!

Students must also provide the correct answer for each question.

Combine students' questions for a quiz at the beginning of their next class.

Extension

Students can investigate the different carbon sinks (WATER, SOIL, ATMOSPHERE) in more detail. They could break these categories down into further categories in terms of time or content, such as layers in the atmosphere, types of oceans or specific ocean regions, types of soil.

Weather Makers - Oceans and sinks

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