Global Warming in 5 Steps

Stephen Taylor, Kauai Community College
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Initial Publication Date: June 3, 2013 | Reviewed: July 21, 2015


Scientists say the planet is warming because of human activities, namely the greenhouse effect from carbon dioxide released to the atmosphere when burning fossil fuels. But, how do we know? How do scientists know?

Students are presented with the following questions:
1) What makes a greenhouse gas a greenhouse gas?
2) Is carbon dioxide a greenhouse gas? [Instructor: How do we know?]
3) Is the amount of carbon dioxide in the atmosphere increasing? How do we know?
4) Is carbon dioxide [in the atmosphere] increasing because of human activities? [Instructor: How do we know?]

---- Discussion of results and prediction of what students expect will happen to global average temperature...
5) Is global average temperature increasing? How do we know?

Separate groups of students research just one question each on the internet and submit a brief summary to the instructor. The instructor and class go over results for just the first four questions. The instructor addresses "How do we know" for questions 2 and 4. Then, students are asked what they think will happen to global average temperature based on results of the first four questions (i.e. make an hypothesis). Finally, the results from the last group are presented and students are asked to discuss how observed global temperature changes compare with their hypothesis.

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The activity is appropriate for any science course where discussion of the physical science basis of global warming is appropriate. The activity is designed for lower-division undergraduate courses for science or non-science majors.

Skills and concepts that students must have mastered

Students should be able to interpret graphs. In particular, they must be able to read axes and legends and discern increasing and decreasing trends from a variety of graphs (line, bar, etc.). Students should have successfully completed high school English such that they have adequate reading comprehension. Students should be independent and confident enough to identify relevant information from among and within scientific agency websites geared toward the general public but much more technical than a newspaper. Students should have successfully completed high school math such that they are somewhat comfortable with ratios and percents. Students should be able to reason such that they can recognize the a series of logical steps. The instructor should at least briefly cover the basic science of the greenhouse effect for 15 minutes or so in a previous class (though not specific to carbon dioxide). The instructor may or may not cover scientific hypotheses and hypothesis testing principles.

How the activity is situated in the course

The exercise could be done in one class or expanded or divided across up to three classes. Additionally, a couple questions could be placed on pre-post tests at the beginning of the course and anytime after the activity is complete.


Content/concepts goals for this activity

  • Describe essential science behind the idea of human-caused global warming.

Higher order thinking skills goals for this activity

  • Demonstrate increased awareness that scientific ideas like human-caused global warming go beyond opinion and are built upon a basis of well-tested physical principles of nature and verifiable observations to support logical conclusions.
  • Provide contextual practice in interpreting scientific source material.
  • Provide contextual practice in interpreting graphs.

Other skills goals for this activity

  • Quickly and easily identify credible internet sources of information.
  • Provide contextual practice with group collaboration by researching and formulating a group report.

Description and Teaching Materials

See student instructions and teaching notes documents for more information.

Teaching Notes and Tips

Students will need access to the interent. See Teaching Notes and Summary of Findings documents for more information.


A pre-post set of questions are recommended. See the attached assessment document.

References and Resources

The exercise does not depend critically on any specific URL. As can be seen in the teacing notes, a number of credible sites will be encountered on the basic searches. As little as one working site may be sufficient to accurately answer the questions. So long as students stick with guidelines for what constitutes credible internet sites (e.g. "edu"), they should find several sources of accurate information at an appropriate level for them to answer the questions. Sites described in the teaching notes are only examples and it should not matter if some of those URLs no longer work.