IPCC Radiative Forcing

Cristina Archer
California State University Chico
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This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.


Students use model results to identify radiative forcings of individual anthropogenic emissions, such as CO2, CH4, O3, PM, etc.

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Upper division class on climate change, for majors of our BS in Environmental Science with option in Climate and Atmospheric Sciences and MS in ES

Skills and concepts that students must have mastered

Students should understand the basics of a climate model, global average, anomaly, error range, scenarios, and a linear vs non-linear system.

How the activity is situated in the course

This activity is used in the second half of the semester.


Content/concepts goals for this activity

  1. Understanding that the climate is non-linear;
  2. Quantitative appreciation of which anthropogenic factors are more and which are less important to climate.

Higher order thinking skills goals for this activity

Other skills goals for this activity

Students gain the practical skills of computing averages, seeing anomalies, looking at various scenarios, and summarizing all of these together.

Description of the activity/assignment

Divide the class in 9-10 groups, one for each of the important climatic forcings that we want to focus on. The groups are of 2-5 students each. For example:
  1. CO2
  2. CH4
  3. N2O
  4. Halocarbons
  5. O3 (tropo)
  6. O3 (strato)
  7. Land use
  8. Aerosol (direct)
  9. Aerosol (cloud albedo)
  10. Solar irradiance (natural forcing).

Then students basically need to arrive at the same numbers that are shown in the IPCC table uploaded here. Each group needs to go find the IPCC model results relevant to their forcing, look at various scenarios/models that were run with that forcing alone and without, generate a range form the scenarios/models and perhaps an average. I do not know if/where the results would be available and if yearly averages are easily found or need to be calculated. I do not know if this can be done in a 2-hr lab session, or perhaps it should be a project. This is just the basic idea, but have not had time to fully expand it. At the end, they all get together and we collect each group's numbers and basically reconstruct the table from scratch. They should not see the table prior to the activity, but show it at the end to compare results. The sum of all their inputs should be close, but not identical, to the global anthropogenic forcing of +1.6 W/m2. Why? Non-linear effects. This could start a discussion on what such effects could be and perhaps use this activity to introduce the concept of climatic feedback.

Determining whether students have met the goals

If they get the same numbers as the IPCC, then they got it right.

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