Sources, Sinks and Feedbacks

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Objective

SWBAT explain how temperature affects the ocean's ability to absorb CO2, and explain the effect of temperature on CO2 uptake by oceans and water vapor in the atmosphere.

Big Idea

Students use a computer model to explore the relationship between ocean surface temperature and levels of CO2 and H2O in the atmosphere.

Getting Started

Students explore the relationships between ocean surface temperature and levels of atmospheric carbon dioxide and water vapor.

Students will be able to:

  • Describe how carbon dioxide travels through Earth's system and identify sources and sinks for carbon dioxide.
  • Explain how temperature affects the ocean's ability to absorb carbon dioxide.
  • Explain the role of water, a greenhouse gas, on Earth's temperature.
  • Explain the effects of temperature on carbon dioxide uptake by the oceans and water vapor in the atmosphere.
  • Describe an example of a positive feedback loop in the Earth system.
  • Explain why it is necessary to consider multiple factors when modeling the climate.

Materials:

  • computers with internet access
  • 500 ml beakers
  • coarse salt
  • thermometer
  • timer

What is the Future of Earth's Climate is the third of five modules on climate change from the Concord Consortium. You could choose to follow the modules in the order presented if you like. I chose to break them apart to fit into the flow of my unit on climate change.

The website says that each module should take about 45 minutes to complete. My students have not needed this much time. 35-40 minutes is more realistic. I would recommend planning on time to debrief and discuss each module in which case you could spend an entire 50-55 minute class per module. 

I have attached the Portal User Guide to setting up a teacher account and creating a class for your reference. 

In addition, the teacher guide can be found here - What will be Earth's climate in the future? 

The modules address the Science and Engineering Practices (NGSS) as well as the Crosscutting Concepts. 

Science and Engineering Practices:

1. Asking questions (for science) and defining problems (for engineering)

2. Developing and using models

3. Planning and carrying out investigations

4. Analyzing and interpreting data

5. Constructing explanations (for science) and designing solutions (for engineering)

6. Engaging in argument from evidence

7. Obtaining, evaluating, and communicating information

Crosscutting Concepts:

1. Patterns

2. Cause and effect: Mechanism and explanation

3. Scale, proportion, and quantity

4. Systems and system models

5. Energy and matter: Flows, cycles, and conservation

7. Stability and change

It also covers the following disciplinary Core Ideas:

ESS3.D: Global Climate Change

Human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming). Reducing the level of climate change and reducing human vulnerability to whatever climate changes do occur depend on the understanding of climate science, engineering capabilities, and other kinds of knowledge, such as understanding of human behavior and on applying that knowledge wisely in decisions and activities. (MS-ESS3-5)

NOTE: This activity runs entirely in a Web browser. Preferred browsers are: Google Chrome (versions 5 and above), Safari (versions 4 and above), Firefox (version 3.6.10 and above), and Internet Explorer (version 7, 8, or higher; note that version 6 or below does not work).

Engage

10 minutes

Open the Dissolving Salt activity with a demonstration to show the effect of temperature on the rate of dissolving salt into water.

Materials

  • 250 ml beakers (2)
  • 100 ml cold water
  • 100 ml hot water
  • 40 g coarse salt
  • Timer
  • Procedure

Ask your students to predict the difference in time to dissolve salt into a beaker of cold water versus hot water. Ask them to give reasoning for their prediction. Give them time to think and write then call on students to share their ideas.

When ready..

Place 100mL of hot water and 100 mL of cold water in two separate beakers. At the same time, pour 20g of salt into each beaker. Start the timer.  Do not swirl, shake, or stir. Set these beakers aside for now. Later (30 min) in the lesson, go back and observe the amount of salt left in the bottom of each beaker. 

In the simulation, the students will learn that the colder the water, the more CO2 will dissolve, whereas with salt the opposite is true. Ask them why this might be so? What is different about the substances (gasses an solids)? Does this provide a clue?

Explore

45 minutes

Have your students get computers and login into the Concord Consortium's High Adventure Science website

I created the Activity 3 - Sources, Sinks, and Feedbacks handout to help in walking your students through the process of logging in and starting module.

They will explore the relationships between ocean surface temperature and levels of atmospheric carbon dioxide and water vapor.

Your students will be able to:

  • Describe how carbon dioxide travels through Earth's system and identify sources and sinks for carbon dioxide.
  • Explain how temperature affects the ocean's ability to absorb carbon dioxide.
  • Explain the role of water, a greenhouse gas, on Earth's temperature.
  • Explain the effects of temperature on carbon dioxide uptake by the oceans and water vapor in the atmosphere.
  • Describe an example of a positive feedback loop in the Earth's system.

Students need 35-45 minutes to complete the activity. The site saves their work as they progress so if they need to stop and start say on a second day or at home, they work is not lost.

Once they finish, ask them to print a copy of their responses and turn these in. 

These ideas are summarized in NASA's Climate Kids Why is the Ocean Important

Below are examples of student responses: 

Explain

45 minutes

As a follow up the the simulation and to connect the science to some current data, I have my students read and summarize the attached article. 

Note: this takes a full class period to introduce and practice the Reading Circles protocol. If time is a constraint, you could assign the article for homework for them to summarize. 

Reading Circles

Working in groups of 8, assign each member of the circle a role. Their task is to look for specific information from the reading and complete a summary related to their role. When they are finished, have them discuss their summaries. 

The roles include:

Summarizer: prepare a brief summary of the reading that covers the key points, main highlights, and general idea of today’s reading assignment.

Questioner/Discussion Director: develop a list of questions that your group might want to discuss about this part of the reading.

Connector: find connections between the reading and you, and between the reading and the wider world.

Illustrator: Draw some kind of picture related to the reading you have just done. It can be a sketch, cartoon, diagram, flowchart, or stick-figure scene.

Travel Tracer: carefully track where the action takes place during today’s reading.

Vocabulary Enricher/Word Wizard: be on the lookout for a few words that have special meaning in today’s reading selection.

Literary Luminary: Your job is to locate a few special sections or quotations in the text for your group to talk over. The idea is to help people go back to some especially interesting, powerful, puzzling, or important sections of the reading and think about them more carefully. The purpose is to suggest material for discussion.

Researcher: Your job is to dig up some background information on any relevant topic related to your reading

 

Refer to the student handout below with directions and answer sheets for each of the roles. 

Credit for this protocol: Compiled by Julie Wachtel, M.Ed.

Key points from each of the sections of the reading  include:

  • Atmospheric CO2 concentrations have reached 400 ppm
  • Land and ocean sinks help insure this number isn’t higher
  • Data included represents past 262 years

 Global carbon emissions and sinks 

  • Since 1760, human activity is responsible for 2K GT of carbon emissions added more carbon to the natural flow that exists.
  • Coal, Oil, Gas, Cement Use and Land Use are the sources of carbon emissions
  • The sinks include the atmosphere, oceans and land.
  • Carbon dioxide added to the oceans, plants, soils and fungi is the result of both greater emission rates and higher atmospheric concentrations = feedback loop where ocean and land sinks absorb more carbon dioxide as more is pumped into the air.
  • Ocean and plants sinks have absorbed 56% of human carbon emissions since 1750.  
  • Without these sinks working overtime atmospheric carbon concentrations would already be well over 500 parts per million

The importance of carbon sinks

  • 7.8 GT  CO2 added to the atmosphere =  increase by 1 part per million.  (879 GT of human carbon emissions since 1750 = 113 ppm in atmosphere)
  • If all human carbon emissions had remained in the atmosphere over the last 260 years atmospheric carbon concentrations = 537 ppm (257 ppm above where they where in 1750).  Excluding land-use emissions = 460 ppm
  • Human emission : coal (+86 ppm), oil (+64 ppm), gas (+26 ppm), cement (+5 ppm) and land-use (+ 76 ppm).
  • Land and ocean sinks working overtime as a result = slowing growth of atmospheric carbon.

The future of carbon sinks

  • Human kind is emitting more and more carbon dioxide, as falling land-use emissions are dwarfed by emissions from our growing use of fossil fuels.
  • Sinks are absorbing more CO2  but the atmospheric concentration is growing at a faster rate than ever.
  • We have to reduce growth rate of global carbon emissions.
  • To stop concentrations growing at all would require an immediate reduction in carbon emissions by 55-60%, followed by further reductions in time.
  • It is not certain that sinks will be able to continue absorbing carbon at this rate.
  • Reducing land use emissions and protecting carbon sinks are also part of the solution