Introduction to the Climate System

Overview

Objectives

By participating fully in this activity, students will learn how to:

• Describe the components of the climate system and explain Earth’s energy balance and the natural greenhouse effect
• Explain how feedback mechanisms, such as the ice-albedo and cloud feedbacks, amplify warming, and what tipping elements in the Earth system are
• Distinguish climate variability from climate change, and identify the natural external and internal drivers of change, such as solar output, Earth’s orbital parameters, volcanoes, and El Niño
• Explain how human greenhouse gas emissions are changing the climate, using evidence such as the Mauna Loa carbon dioxide record
• Describe what climate models are, how scenarios are used, and where uncertainties in projections come from
• Explain the roles of the IPCC and the UN climate conferences (COPs) in climate policy, and identify actions governments and individuals can take

Grade Level

Grades 9-12, Undergraduate

Standards

These are Next Generation Science Standards (NGSS) performance expectations.

• HS-ESS2-4 — Use a model to describe how variations in the flow of energy into and out of Earth’s systems result in changes in climate.
• HS-ESS3-5 — Analyze geoscience data and the results from global climate models to make an evidence-based forecast of the current rate of global or regional climate change and associated future impacts to Earth systems.
• HS-ESS3-1 — Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.

This lesson also supports these international frameworks:

• Global competence (Asia Society and OECD): Investigate the world
• UNESCO learning objectives for SDG 13 (Climate Action):
  • Cognitive 1: the greenhouse effect as a natural phenomenon
  • Cognitive 2: current climate change as caused by human greenhouse gas emissions
  • Cognitive 3: which human activities contribute most to climate change
  • Cognitive 4: the ecological, social, cultural and economic consequences of climate change

United Nations Sustainable Development Goals

• SDG 4 — Quality Education: Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all
• SDG 13 — Climate Action: Take urgent action to combat climate change and its impacts

Materials Required

• PDF slideshow “Reboita_Introduction to Climate System_191123.pdf” (Introduction to the Climate System, Michelle Reboita)
• Paper and pencil
• This discussion guide, since the lecture slides do not include built-in discussion prompts

Learning Sequence

Lesson Plan Introduction

Before students can weigh responses to climate change, they need to understand how the climate system works. This lesson builds that foundation in six sections, and with 112 slides it can be taught across several class periods, one or two sections at a time.

Activity Details

1. The Climate System (Slides 1–38)

• Introduce the energy entering and leaving Earth and the components of the climate system, as defined in the IPCC glossary (slides 3–8).
• Explain the layers of the atmosphere, solar and terrestrial radiation, and Earth’s energy budget, from the solar constant of about 1362 W m⁻² to the roughly 30% of sunlight reflected back to space (slides 9–22).
• Present the natural greenhouse effect: without it, Earth’s average temperature would be about −18°C (slides 23–30).
• Explain feedback mechanisms, including the ice-albedo and cloud feedbacks, and five tipping elements in the Earth system (slides 31–37). Slide 38 links a Met Office video that summarizes the section.
• Discussion question: Why does melting ice speed up warming, and could that feedback ever reverse?

2. Natural Climate Variability and Change (Slides 39–58)

• Distinguish climate variability from climate change, and show that climate has changed even without humans (slides 39–41).
• Present the external natural drivers: solar luminosity and sunspots, Earth’s orbital (Milankovitch) parameters and the ice ages, and volcanic eruptions (slides 42–53).
• Present the internal drivers: ocean currents and teleconnections such as El Niño (slides 54–58).
• Discussion question: If climate has always changed naturally, how can scientists tell that today’s warming is caused by humans?

3. Human-Caused Climate Change (Slides 59–82)

• Show the rising temperature by decade and explain how greenhouse gas emissions strengthen the greenhouse effect (slides 59–62).
• Identify the main greenhouse gases and their human sources, and present the carbon dioxide record from Mauna Loa and countries’ historical responsibility for emissions (slides 63–76).
• Review the evidence and indicators of climate change, including more frequent and intense extremes, and the IPCC’s Sixth Assessment Report (slides 77–82).
• Discussion question: Should countries that emitted the most carbon dioxide in the past carry more responsibility for solving climate change? Why or why not?

4. Climate Modeling (Slides 83–94)

• Explain what climate models are (numerical codes that solve the physical equations of the climate system) and the main model types (slides 83–87).
• Discuss horizontal resolution, how models are validated against observations, and how scenarios describe possible futures (slides 88–91).
• Explain the sources of uncertainty in projections: the pathway society will follow, and differences between models (slides 92–94).
• Discussion question: If models are simplifications of reality, why should we trust their projections?

5. Climate Change and Policy (Slides 95–104)

• Present the IPCC, created in 1988, and its assessment reports from 1990 to 2021 (slides 95–97).
• Explain the UN Framework Convention on Climate Change and the COP climate conferences, with a timeline through COP28 in 2023 (slides 98–104). Update this section with the most recent COP.
• Discussion question: What makes it hard for nearly 200 countries to agree on climate action?

6. Consequences and Actions (Slides 105–112)

• Present the consequences of climate change for people, such as effects on health and food security (slides 105–106).
• Review actions for governments, such as regulating emissions, investing in clean energy, and planning greener cities, and for individuals, such as using public transport, reducing waste, and eating less red meat (slides 107–109).
• Close with the conclusion (slides 110–112). Slide 111 links an article with the complete text of the presentation.

Conclusion

Close with a values-based question: Which actions to address climate change should be the responsibility of governments, and which of individuals? Which action from this lesson could you take this week?

Global Connections

Needs review: Claude drafted the Global Connections section, and the global competence and UNESCO SDG 13 entries under Standards, from the lesson materials. Review and edit them.

Start where you teach

Have students look up their own place's average temperature and rainfall and one recent extreme event, and use them to tell climate variability from climate change.

Bring in other perspectives

Before the slides on the IPCC and the UN climate conferences, have groups look up their own country's climate pledge (its nationally determined contribution) and compare it with another country's.

Share beyond the classroom

Students can explain one feedback or tipping point to a younger class or to their family, and report back which ideas were hardest to get across.

Lesson materials

Download the files below to teach this lesson. PDFs are accessible versions; PowerPoint and Excel files can be edited for your class.

Teacher resources

• Lesson slides

  • Download PDF: Lesson slides

• Climate system in a nutshell: An overview for understanding climate change

  Reboita’s article in the International Journal of Development Research with the complete text of this presentation, linked on slide 111.

  • Open Link: Climate system in a nutshell: An overview for understanding climate change

• How does the climate system work?

  Optional. Met Office video summarizing the first section, linked on slide 38. It is on YouTube only; where YouTube isn't available, skip it, since slides 1–37 cover the same material.

  • Watch YouTube video: How does the climate system work?

Related lessons

• Climate Change and Solar Radiation Modification: Science, Risks, and Who Decides: teach next: the same author's lesson on responding to climate change, including solar radiation modification

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