Three-dimensional Learning Progression In Lesson 4 students studied global CO2 fluxes changed atmospheric CO2 concentrations, including the key role of the human-caused flux from burning fossil fuels. In Lesson 5 the studied human technological systems and activities and how they contribute to the unbalanced fossil fuel flux. In Lesson 6, they return to the global scale, considering how this unbalanced flux affects other aspects of Earth systems, such global temperatures, sea level, and Arctic sea ice. They use computer models to map out different scenarios for the future, studying how the future of the planet will depend on humans’ activities and decisions. Our goal is to help students see how those models are grounded in the scientific models and principles that they have studied, and to appreciate both the power and the limits of those models. Key Ideas and Practices for Each Activity Activity 6.1 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 6.2 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 6.3 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. Activity 6.4 of the unit is a posttest, enabling you to monitor your students’ progress in understanding patterns in Earth systems, including climate change and global carbon cycling. Key Carbon-Transforming Processes: Combustion, Photosynthesis, Fossil Fuel Formation, Cellular Respiration Content Boundaries and Extensions
