Directions for teachers: Ask students to skim the Science News Explores article “Explainer: CO₂ and other greenhouse gases” and answer the first set of questions. Then ask students to read the introduction of the Science News article “It’s possible to reach net-zero carbon emissions. Here’s how” and answer the remaining questions. A version of the article, “The road to net-zero,” appears in the January 28, 2023 issue of Science News.

Check out our Grappling with graphs and other data visualizations lesson plan for more graphical analysis questions.

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

Reviewing greenhouse gases

1. Name at least three greenhouse gases. Where do they come from?

Carbon dioxide, methane, nitrous oxide and fluorinated gases are greenhouse gases. Carbon dioxide is produced by plants and is part of Earth’s natural carbon cycle. Humans release additional carbon dioxide into the atmosphere by burning fossil fuels such as coal and oil. Other greenhouse gases such as methane and nitrous oxide are also naturally present in the Earth’s atmosphere. Humans emit extra amounts of these gases into the atmosphere via agricultural processes and the production and combustion of fossil fuels.

2. What effect do greenhouse gases have on the Earth? Why does the article compare greenhouse gases to a blanket or a window of a greenhouse? Come up with your own metaphor to describe the effect of greenhouse gases in the atmosphere.

Greenhouse gases trap heat in the atmosphere and warm Earth, like how a blanket traps body heat to keep us warm or a greenhouse window traps the sun’s energy to keep plants warm and help them grow when it is cold outside. Another metaphor could be a jacket. 

3. How do human activities impact the atmosphere’s concentration of greenhouse gases? What effect does that impact have on climate and weather? 

Human activities release additional amounts of greenhouse gases into the atmosphere at an increased rate, which increases the concentration. As a result, Earth’s global average temperature is increasing, sea levels are rising and oceans are absorbing extra carbon dioxide and becoming more acidic, which affects marine organisms. The frequency, intensity and duration of extreme weather events are also increasing.

4. With your partner, draw a simple diagram depicting the relationship between Earth’s temperature and the concentration of greenhouse gases in the atmosphere. Make sure that your diagram includes various sources of greenhouse gases. Your diagram should also indicate how human activities impact the natural cycle and concentration of greenhouse gases in the atmosphere over time.

Student answers will vary but should show how some greenhouse gases are emitted naturally and warm the atmosphere. Diagrams should then indicate that human activities continue to increase the concentration of the gases in the atmosphere and therefore the global average temperature.  

Achieving net-zero

1. Before reading the Science News article, discuss with a partner what you think the term “net-zero” means.

The term “net” generally means the sum of all, so “net-zero” means the sum of all is equal to zero.  

2. After reading the Science News article, discuss what “net-zero” means in the context of the article. Then, look at the graph titled “Carbon dioxide emissions by sector in one net-zero scenario,” and discuss how changes in each of the sources of carbon dioxide could help achieve net-zero emissions by 2050.

In the article, “net-zero” refers to the sum of all human-made greenhouse gas emissions equaling zero. The graph shows a scenario where over the course of about the next 30 years, electricity and heating as well as “other” sources will take more carbon dioxide out of the atmosphere than they emit. Industry and transport sources will reduce the amount of carbon dioxide they emit, but those sectors may not achieve zero emissions by 2050. Still, if other industries take more carbon dioxide out of the atmosphere than they emit, net-zero emissions may still be achievable by 2050.

3. If you are reading the story in print, check out the at-home and industrial milestones shown below the graph. Discuss which milestone would impact you and your local economy the most. What might be some benefits and challenges of the change? 

Student answers will vary.

4. The article states that “the key to a decarbonized future lies in producing vast amounts of new electricity from sources that emit little to none of the gases.” Discuss this statement with your partner and draw a diagram to help explain why it’s true.

Electricity from renewable sources such as the wind, the sun and water is important to shrinking society’s carbon footprint. If electricity continues being made by burning fossil fuels and emitting greenhouse gases, then new technologies or tools that depend on electrification won’t be truly carbon-free, or “clean.” Diagrams should indicate how new, electrified technologies would still produce greenhouse gases if they do not run on clean electricity.