Lesson Greenhouse Atmosphere:
Let's Heat Things Up!

Learning Objectives

After this lesson, students should be able to:

• Understand that human activities have increased carbon dioxide concentrations (air pollution).
• Explain global warming.
• Understand that carbon dioxide gas is a greenhouse gas, and its increased concentration in the atmosphere is contributing to global warming.
• Describe how global warming may impact an engineer's decisions, their own lives and the Earth.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Worksheets and Attachments

Introduction/Motivation

(Ask students to do a "splash sheet" about the greenhouse effect and global warming. A "splash sheet" is similar to a brainstorm, but includes pictures, diagrams, or words to help students quickly jot down their ideas. Consider assigning this as homework the night before the lesson.)

(Have students share the ideas from their splash sheets in class.)

The Earth is getting warmer. The annual average global temperature has increased 1.8°F (1°C) from 1901 to 2016. Scientists attribute this observed global warming trend to the increased greenhouse effect. What is the greenhouse effect? Maybe you have already felt a miniature version of the greenhouse effect. Has this happened to you? It's a hot summer day and your parents have parked the car in the sun and no one opened the windows. How does it feel inside the car? It is very hot because the sun's energy is trapped inside the car. When you feel that trapped energy as heat, you have just felt the greenhouse effect. This is why no one should be left in a car on a warm, sunny day (including pets), because the inside temperature of the car can become over 100ºF (37.8°C), even with the windows slightly opened! The sun warms our planet. We feel the sun's energy as heat, but more of this heat is getting trapped near Earth by greenhouse gases like carbon dioxide.

Human activities are changing the Earth's natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of carbon dioxide in the atmosphere. Scientists predict that the Earth's temperature will continue to rise. According to the Environmental Protection Agency (EPA), electric utility companies, industry, businesses, homes, and transportation cause carbon dioxide levels to build up in our atmosphere.

From where does carbon dioxide come? (As necessary, review the carbon cycle with the students; see The Carbon Cycle Diagram attachment.) Why is it considered such a problem? What does it have to do with the greenhouse effect and global warming?

Lesson Background and Concepts for Teachers

The Earth's climate has changed many times in the past. Subtropical forests have spread from the south to more temperate (milder, cooler climates) areas. Millions of years later, ice sheets spread from the north covering much of the U.S., Europe and Asia with glaciers. Today, our climate appears to be changing again, but this time scientists think that humans activity is the major cause.

The Greenhouse Effect

The greenhouse effect is a naturally occurring phenomenon in which the specific gases in the atmosphere of the Earth trap heat from the sun (see The Greenhouse Effect Diagram attachment). Typically, our atmosphere absorbs just the right amount of heat so that living things can survive. Essentially, the atmosphere acts like the glass in a greenhouse. As a result of this, the Earth's surface is about 58°F (14°C) warmer than it would be without the greenhouse effect. (Refer to the activities Greenhouse Effect Models: Hot Stuff! and It's Really Heating Up in Here! to help students illustrate the development of the greenhouse effect by designing and analyzing simple models.)

Gases that trap heat in the atmosphere are called greenhouse gases, and the primary greenhouse gases on Earth are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Of these, carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFCs), have an appreciable greenhouse effect, and are being released in large quantities by human activity. These gases, except for CFCs, come from both natural and human-made sources, and the higher their concentration in the atmosphere, the warmer the Earth's temperature becomes.

• Carbon dioxide comes from natural processes (like decaying and living organisms and volcanoes), but it also is released when fossil fuels (like coal and oil) are burned.
• Methane is released from natural decay, wetlands, growing rice, raising cattle, using natural gas, and mining coal.
• Nitrous oxide is not only naturally released by bacteria in the soil and the oceans, but also emitted by certain types of factories, power plants and plant fertilizers. 
• CFCs are a class of human-made chemicals once commonly used in air conditioners, refrigerators and as the pressurizing gas in aerosol spray cans.

Global Warming

Global warming is the increase in  the Earth's average atmospheric temperature over a long period of time, generally due to increased levels of greenhouse gases caused by human activities. Scientists believe that even a 2-3ºF (0.6-1.1°C) increase in the average temperature of the Earth could trigger disasters.

According to the National Oceanic and Atmospheric Administration (NOAA), between 1880 and 1980, the global annual temperature increased at an average rate of 0.13°F (0.07°C) per decade. Since 1981, the global annual temperature has increased at twice that rate, 0.32°F (0.18°C). This has led to an overall 3.6°F (2°C) increase in global average temperature today compared to the pre-industrial era. In 2019, the average global temperature (over land and ocean) was 1.75°F (0.95°C) above the 20th-century average. This made 2019 the second hottest year on record, behind 2016. 

This rise in average global temperature is caused by human activities, particularly the burning of fossil fuels. The amount of carbon dioxide entering the atmosphere increases when fossil fuels are burned and the excess carbon dioxide cannot be used by plants (especially since we are eliminating them, too). The excess carbon dioxide in the atmosphere absorbs heat from the sun and keeps it near the surface of the Earth, which raises the Earth's temperature. The concentration of carbon dioxide in the atmosphere has doubled in the last 100 years and scientists expect it to double in the next 100 years as well.

Scientists predict that these changes will trigger disaster. For example, a major shift in weather patterns could cause droughts, tropical storms and increase temperatures that would make some currently habitable areas of the Earth become uninhabitable. Scientists also predict that melting polar ice caps could cause a rise in sea levels and, in turn, flood low-lying areas, such as coastal cities like New York City and San Francisco. The melting of the icecaps could also dilute marine saline concentrations, threatening marine life.

While most scientists believe that the greenhouse effect will gradually warm the Earth's climate, some scientists predict that as the temperature rises, more water will evaporate from the oceans, resulting in more clouds. This increase in clouds could block out sunlight, causing an overall decrease in the Earth's average temperature. This increased atmospheric reflectivity is called an increase in the Earth's albedo.

Photosynthesis

Forests have been called the "lungs of the Earth" because animals inhale oxygen and exhale carbon dioxide in the process of breathing, and plants take in carbon dioxide and give off oxygen in the process of photosynthesis. See The Carbon Cycle Diagram attachment.

As of 2019, more than 78 million acres of tropical forest are cut and burned each year to clear land for farming and ranching. According to the World Resources Institute, averaged over 2015 – 2017, global loss of tropical forests contributed about 4.8 billion tonnes of carbon dioxide per year (or about 8-10% of annual human emissions of carbon dioxide).

Engineering

Environmental engineers are concerned about photosynthesis because plants help clean the air of harmful carbon dioxide gas, replacing it with oxygen. With the decreasing numbers of trees in the world, the air is not being cleaned as well. Additionally, the carbon dioxide levels continue to increase due to increasing numbers of automobiles and industrial pollution. Environmental engineers are continually challenged to find methods to reduce carbon dioxide emissions from industry and cars, and find ways to clean our polluted air. Students can explore taking the matter into their own hands with the literacy-based associated activity Pollution Politics.

Associated Activities

• Greenhouse Effect Models: Hot Stuff! - Students observe demonstrations, and build and evaluate simple models to understand the greenhouse effect and the role of increased greenhouse gas concentration in global warming.
• It's Really Heating Up in Here! - Students create and observe a greenhouse effect model and discuss the implications of global warming theory for engineers, themselves and the Earth.

  Watch this activity on YouTube

• Pollution Politics - In this literacy activity, students learn how a bill becomes law in the U.S. Congress, and research legislation related to global warming.

Lesson Closure

Ask students to create a final, more detailed and thoughtful splash sheet describing their full understanding of the greenhouse effect and global warming. Consider using butcher block paper or large, bulletin board-size paper for the splash sheets. Display these in the classroom or a school common area.

Have the students create a pie chart or bar graph using the data on the Sources of CO₂ Emissions attachment (see the Assessment section for details).

Vocabulary/Definitions

albedo: The reflectivity of a substance, usually a percentage of the amount of incoming radiation that is reflected.

global warming: A gradual increase in the overall temperature of the earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, chlorofluorocarbons, and other pollutants.

greenhouse effect: A naturally occurring phenomenon in which the atmosphere of the Earth traps heat from the sun.

habitable: The idea that a place is suitable to live in or on.

photosynthesis: The process by which plants take in carbon dioxide and give off oxygen.

Assessment

Pre-Lesson Assessment

Splash Sheet: Ask students to create a "splash sheet" about the greenhouse effect and global warming. A splash sheet is similar to a brainstorm, but includes pictures, diagrams, words, etc., to help students quickly jot down their ideas. Consider assigning this as homework the night before the lesson. If done in class, provide students with large sheets of butcher block paper on which to create their splash sheet.

Questions: Have students come up with questions to ask each other about global warming (i.e., what factors have caused the rise in global temperatures over the past century?) After the lesson, have students answer the questions.

Post-Introduction Assessment

Question/Answer: Ask students: From where does carbon dioxide come? (As necessary, review The Carbon Cycle Diagram with the students.) Why is it considered such a problem? What does it have to do with the greenhouse effect and global warming?

Lesson Summary Assessment

Graphing: According to the U.S. Environmental Protection Agency, the sources of carbon dioxide emissions in the U.S. in 2018 were: 34% from transportation, 32% from electricity generation, 15% from industrial, 11% from residential and commercial, and 7% from other non-fossil fuel combustion. Using this data, have students make a pie chart and/or a bar graph. Ask them to include a paragraph explaining what the graph represents and how this information relates to the greenhouse effect and global warming. Refer to the Sources of CO₂ Emissions attachment.

Create a Poem: Have the students write a short poem that expresses what they understand about global warming and how it may affect our environment in the next 50 years.

Lesson Extension Activities

Explore carbon monoxide production in more detail. Will our individual efforts really make a difference or do we need to address carbon dioxide production at another level? Are there other greenhouse gases to which we should be paying more attention?

Have students act out the greenhouse effect. Some students can be a carbon dioxide wall, some can be the Earth, and others can be the trapped energy between the greenhouse gasses and the Earth.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.