Participatory Learning in Climate Change Law Policy, Part 1

Over the next few weeks, I’ll post a few entries about using participatory learning activities in a Climate Change Law and Policy class.  I’ve just taught the class at the University of San Diego School of Law for the third time, and I have a few ideas to share.  I teach a three-hour seminar with no more than 20 students, which is a great length and size for doing such activities.

After an initial class focused on the science of climate change, we spend the second class on climate change mitigation.  For this, I use the Stabilization Wedge Game materials posted on the website of Carbon Mitigation Initiative (CMI), Princeton University (  The game was developed by Princeton professors, Stephen Pacala and Robert H. Socolow, based on their article entitled “Stabilization wedges: Solving the climate problem for the next 50 years with current technologies,” Science, 305, pp. 968-972 (2004).  The articles presents 15 technological strategies to reduce emissions such as mass adoption of solar (i.e. an array of photovoltaic panels with an combined area about 12 times that of metropolitan London would provide one wedge) or widespread energy efficiency retrofits (i.e. replacing all the world’s incandescent bulbs with compact fluorescent lights would provide 1/4 of one wedge.)  Some of the strategies are dated, particularly the ones involving hydrogen, but they still give a great sense of the types of technological change that are being called for.

I assign the Pacala and Socolow article as reading for the class, and I use the first part of class to talk through the mitigation technologies proposed in the article and answer any student questions.  Then I break the class into 4 or 5 groups, and they play the game, meaning that they select seven wedges representing technologies that could be implemented to stabilize atmospheric concentrations of CO2 at 500 ppm, as suggested by the authors’ model.  They generally take about 30 to 45 minutes to play the game, and they spend about 15 more minutes presenting their solutions to each other.

Then we debrief.  There is a lot that can be discussed:

1)      Many scientists now think that we need to stabilize atmospheric concentrations at a level much lower than 500 ppm – 450, 400 or even lower (we are currently at about 380 ppm.)  To do this, you need more wedges. See Joe Romm’s Grist post,, for a discussion of how many wedges are needed to stabilize concentrations at acceptable levels given that we have continued to emit at ever higher rates in the past five years since the original analysis.  Here’s a preview: to stabilize at 450 ppm, we’ll need 14 wedges assuming we start next year.

2)      The game doesn’t provide much information about the costs of implementing the proposed strategies.  It gives a very rough estimate of cost for each approach symbolized by one, two or three $ signs.  Thinking seriously about costs – and the uncertainty of costs – makes decision-making more difficult.

3)      One of the premises of the article (and game) is that all the proposed technologies are available. Yet several have not been proven feasible at the scale that they would have to be implemented, such as strategies involving carbon capture and storage.  I have sometimes assigned an article that makes this argument, Hoffert, et al (2002) “Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet.” Science,  298: 981-987.  Hoffert et al. argue that while a strategy may be technically available, it may require a large amount of government or private investment to make it available at the scale envisioned by Pacala and Socolow.

4)      The model does little to help understand the political challenges of various strategies.  Energy efficiency and conservation approaches are popular with students, but they tend to be difficult politically because they involve lifestyle choices.  And then there’s the wedge for nuclear power…  More generally, the model considers the needed changes in the world as a whole, without consideration of the political and social differences (and inequities) regionally, nationally, and subnationally.

Despite its limitations, the game is a useful interactive vehicle for getting law and policy students to understand something about the various emissions reduction technologies.  And the really great thing about the game is that it makes the problem of reducing emissions seem tractable while at the same time communicating what a huge challenge it will be.

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