Directions for teachers:

Have students read the online Science News article “The new UN Climate change report shows there’s no time for denial or delay” and answer the related comprehension questions for homework, or have students read the article as a quick warm-up at the beginning of class. A version of the article, “Earth cannot avoid a warmer future,” appears in the September 11, 2021 issue of Science News.

As a class, discuss the first set of questions below. Then have students answer the second set of questions with a partner. Finally, assign each pair an impact from the “Feeling the heat” chart in the Science News article to analyze. The students will use the third set of questions to create a data visualization for their assigned impact. If time permits, consider having students share their visualizations with the class.

Want to make it a virtual lesson? Post the online Science News article to your virtual classroom. Discuss the article and questions with your class on your virtual platform.

So many scenarios

1. What are climate scenarios?

Climate scenarios forecast how much the world could warm relative to preindustrial times due to greenhouse gas emissions and what the effects of that warming might be. The scenarios are based on data and climate models.

2. What do the four scenarios outlined in the “Feeling the heat” chart in the Science News article represent?

The first scenario describes the climate impacts of today’s level of warming — about 1.1 degrees Celsius warmer than preindustrial times. The next two scenarios forecast what the climate impacts could be if we cut greenhouse gas emissions enough to limit global warming to around 1.5 degrees C and 2 degrees C. The final scenario forecasts what the climate impacts could be if the average global temperature rises by 4 degrees C relative to preindustrial times.

3. Why do you think scientists look at more than one scenario in climate change studies? Think about what determines how much climate will change in the future.

Changes in human activity such as population size, fossil fuel consumption and land use affect greenhouse gas emissions, which contribute to global warming. Evaluating multiple scenarios allows scientists to look at the climate impacts for different amounts of emissions and thus different amounts of warming. Setting out these scenarios could help people make decisions about how to change and how much to change their activities going forward.

4. How might understanding different climate scenarios and their impacts benefit policy makers around the world?

Knowing how increases in global temperature will affect weather patterns and extremes, and thinking about how those changes may affect people, could inform policy makers’ decisions about how to regulate carbon emissions.

5. Why do you think it is important for you to understand how scientists use climate change scenarios? Explain.

Answers will vary, but students might mention that knowing how scientists investigate the potential impacts of climate change could help students understand what they read about climate change in the news. For instance, if students read about how much snow cover extent might decrease over the next several decades, they will know that the forecast is based on some specific climate scenario. They may want to investigate what scenario was used for the forecast.

Data dive

1. Look at the chart titled “Feeling the heat” in the Science News article. In your own words, describe what the chart shows. Make sure to state any units of measurement used, and compare your answer with your partner’s answer.

The chart shows how much worse than preindustrial levels extreme weather events will be according to four climate scenarios. Global temperatures based on different levels of greenhouse gas emissions are given as a number of degrees over the average global temperature from preindustrial times. Today’s temperature is given as +1.1 degrees C relative to preindustrial times. The extreme weather events in the chart are related to temperature, drought, precipitation, snow and tropical cyclones.

2. Choose two data points off the chart for your partner and have them explain the meaning of the points to you. Make sure your chosen points are different than the points your partner chooses. Take time to think through your answers before taking turns explaining the data points to each other.

Student answers will vary. As an example, if students choose the point for drought and +2 degrees C, they should explain that if the average global temperature is 2 degrees C warmer than it was during preindustrial times, then a once-in-a-decade drought is 3.1 times as likely to occur.

3. Look at the climate impacts for the +1.5 degrees Celsius scenario and the +2 degrees C scenario. Based on the chart and the rest of the Science News article, how does half a degree of warming affect the severity of extreme events? Use one extreme event given in the chart as an example to help explain your reasoning. Think about differences in severity relative to preindustrial times and relative to now.

The effect that 2 degrees C of warming has on extreme conditions versus the effect that 1.5 degrees C of warming has is substantial, according to a special IPCC report. For instance, the likelihood of heat waves increases more under the +2 degrees C scenario than it does under the +1.5 degrees C scenario. According to the chart, that extra half-degree of warming means that the hottest day in a decade could be 2.6 degrees C hotter relative to preindustrial times as opposed to 1.9 degrees C hotter. Relative to today, that’s 1.4 degrees C hotter versus 0.7 degrees C hotter.

Diagram the data

1. Check in with your teacher to determine which extreme weather event you and your partner should explore. State which extreme event you are investigating. What geographic regions do you think will be most affected by changes in the severity of that event?

Student answers will vary.

2. Draw a diagram to represent the relative data for your assigned extreme event under each of the four climate scenarios in the “Feeling the heat” chart. Make sure that your data visualization correctly represents the relative changes in severity for the different scenarios.

Student diagrams will vary, but should accurately represent the data given for a particular extreme event. 

3. Explain how you could determine the rate of change in severity of your extreme event.

Student answers will vary. Students could graph the severity data relative to the projected temperature increases to determine the rate of change.