EDUCATION: GLOBAL METHANE INVENTORY

Lesson 1-1: The Role of the Atmosphere and Greenhouse Effect in Determining the Surface Temperature of the Earth

The following lesson is a Methane Project Interactive Lesson.

Specifications

Time: 2 to 3 class periods

Learning Objectives

At the end of this lesson, students will be able to:

• Use a model to investigate the relationship between radiative balance and the Earth's surface temperature, conducting three experiments:
• Scenario 1: no atmosphere
• Scenario 2: an atmosphere without greenhouse gases
• Scenario 3: an atmosphere with greenhouse gases
• Use graphical data to investigate the historical trends in greenhouse gas concentrations.
• Calculate the percent change in greenhouse gas concentrations for a given time period.
• Use a model to see the effect of the percent change in greenhouse gases might affect global temperature.

Credits

Developed at the Institute on Climate and Planets, NASA Goddard Institute for Space Studies by Harvey Augenbraun, Teacher of Earth Science, The Mott Hall School, I. S. 223 (Grades 4-8), New York City, August 1997.

The interactive courseware module for this lesson was created by Samuel Borenstein, Professor of Physics York College, City University of New York.

Using the Interactive Software

To use the interactive courseware module described in this lesson, you will need:

• a PC running Windows 95 / 98 or later versions
• a web browser: Netscape Navigator or Internet Explorer
• plug-in "Neuron" installed (available here)
• the module (available here)

Science Content

The Greenhouse Effect is an important and timely topic in the study of Earth science. In topic 1 the student will use an interactive computer module to investigate the nature of the natural greenhouse effect and its effect on making the Earth a habitable planet. By looking at the relationship between insolation at the Earth's surface and radiation of infra energy from the surface, the student will investigate:

• What would the Earth's surface temperature be if there was no atmosphere?
• What would the Earth's surface temperature be if there was an atmosphere with no greenhouse gases?
• What would the Earth's surface temperature be if there was an atmosphere with greenhouse gases?

At the completion of this section the student will determine that the greenhouse effect is natural and necessary for making the Earth a habitable planet.

Continuing with this module, students will investigate historical changes and trends in greenhouse gas concentrations, both natural and anthropogenic (created by people), for the pre- and post-industrial era. They will also investigate:

• What were the corresponding temperature changes during these periods?
• What is the human impact on greenhouse gas concentrations?
• What might result if the present trends in atmospheric concentration of greenhouse gases continue?

At the completion of this section, students will discover that greenhouse gases vary naturally. They will also discover the human influence on changing rates of increase in greenhouse gas concentrations during the post-industrial era.

Science Skills

Skills used:

• Use of technology
• Data analysis
• Mathematical reasoning

Students will interpret historical graphical data for atmospheric concentrations of greenhouse gases derived from analyses of ice core samples and more recent direct measurements of air. From this they will derive atmospheric concentrations of carbon dioxide and methane for 120,000 and 20,000 years ago and compute the percent change for each gas over the time period. These values may then be input to the computer program which will calculate the change in temperature that results*. They will repeat the procedure for the time period from 1800 to the present.

From the analysis of these data the student will see that:

• Concentrations of atmospheric greenhouse gases vary naturally with time.
• Human activity may influence the rate of change in atmospheric concentrations of greenhouse gases.

The student can predict what might occur to concentrations of greenhouse gases if present trends continue. As an optional activity they can vary the concentrations of these gases and use the program to compute temperature changes^*.

^* The resulting temperatures are what would occur if the change in greenhouse gas(es) were the only factor. In reality there are other factors involved which produce the final surface temperature.

Teacher Notes

• For the first three sections, the teacher can take students through each step, explaining what the module shows at each step or the students may do it on their own as they go through the questions.
• For the last two sections, Natural Changes and Anthropogenic Changes in Concentrations of Greenhouse Gases, the students should get the data from the graphs, do the calculations to find the percentage change in greenhouse gas concentrations, then use those values in the courseware module to find the change in global temperature that might result from those increases in greenhouse gas concentrations.

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