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Human Energy Systems | Lesson 6 - Global Implications & Posttest

Lesson 6: Global Implications & Posttest

Students consider the impacts that rising carbon dioxide levels have on the Earth’s systems, discuss uncertainty in climate models and predictions, and consider the future of Earth’s systems given different CO2 emissions scenarios.

Guiding Question

What does increasing CO2 in the atmosphere mean for the planet?

Activities in this Lesson

  • Activity 6.1: Making Predictions About The Future of Earth’s systems (30 min)
  • Activity 6.2: Using Models to Predict Future Conditions (50 min)
  • Activity 6.3: How Our Decisions Affect Earth’s Future (30 min)
  • Activity 6.4: Human Energy Systems Unit Posttest (20 min)


  1. Use large-scale data sets related to climate change (Arctic Sea ice, atmospheric CO2 long-term trend, and atmospheric CO2 short-term variability) to make predictions about the future.
  2. Distinguish between short-term variability and long-term trends in large-scale data sets.
  3. Describe energy as flowing through Earth systems, from sunlight to chemical energy to heat that is radiated into space.

NGSS Performance Expectations

Middle School

  • Human Impacts. MS-ESS3-4. Construct an argument supported by evidence for how increases in human population and per-capital consumption of natural resources impact Earth's systems.
  • Earth and Human Activity. MS-ESS3-3. Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment.
  • Earth and Human Activity. MS-ESS3-5. Ask questions to clarify evidence of the factors that have caused the rise in global temperatures over the past century.

High School

  • Ecosystems: Interactions, Energy, and Dynamics. HS-LS2-5. Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.
  • Earth and Human Activity. HS-ESS3-6. Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.
  • Ecosystems: Interactions, Energy, and Dynamics. HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
  • Earth’s Systems. HS-ESS2-2. Analyze geoscience data to make the claim that one change to Earth’s surface can create feedbacks that cause changes to other Earth systems.
  • Weather and Climate. 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.
  • Earth and Human Activity. HS-ESS3-4. Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.
  • Earth and Human Activity. 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.

Background Information

Activity 1 helps students examine how to use data from large-scale data sets to make predictions about what will happen in the future. This activity aims to help students distinguish between data sets that have predictable short-term variation (like the Keeling Curve) and data sets that have unpredictable (random or stochastic) short-term variation (like arctic sea ice, global temperature, and sea level rise). We can use the stable seasonal cycle in the Keeling Curve to make predictions about CO2 levels in the future months, years, and long term. This is because the short-term variation is due to a predictable flux of carbon atoms between the atmosphere and the biomass as a result of photosynthesis and cellular respiration. The long-term trend, which is a result of fossil fuel consumption, can be used to make predictions further into the future. Other phenomena such as Arctic Sea ice extent, global temperatures, and sea level have much more random variation that affect their short-term patterns and make them less useful for making precise predictions about the next few years. However, we can use the long-term trends in these data to make predictions about overall patterns in the future.

Activity 2 uses a very simple climate model to make predictions about future atmospheric CO2 concentrations and global temperatures. Using this model students learn that even if CO2 emissions remain constant or begin to decrease, atmospheric CO2 (and therefore global temperatures) will continue to rise over the next century.

Activity 3 helps students begin to think about how our decisions affect Earth’s future. This activity builds on the simple climate model in Activity 2 to show how scientists use models to predict what Earth’s systems might look like in the future based on various emissions scenarios. These models operate with a degree of uncertainty, but are useful for examining how different emissions scenarios or mitigation strategies may affect Earth’s systems. We want the students to understand that computer models are useful even if they cannot predict the future with 100% accuracy, and that long-term trends from the past are valuable pieces of evidence on which to base future projections. This lesson concludes with questions about how our actions affect Earth’s future that you may wish to investigate further.

The final activity of the unit is a posttest, enabling you to monitor your students’ progress in understanding carbon-transforming processes associated with human energy systems.

Key Carbon-Transforming Processes: Combustion, Photosynthesis, Fossil Fuel Formation, Cellular Respiration