Stabilization Wedge Game
The Stabilization Wedge Game, or what is commonly referred to as simply the 'Wedge Game', is a serious game produced by Princeton University's Carbon Mitigation Initiative. The goal of the game creators, Stephen Pacala and Robert H. Socolow, is to demonstrate that global warming is a problem which can be attacked right now by using today's technologies to reduce CO2 emissions. The object of the game is to stabilize CO2 concentrations under 500ppm for the next fifty years, using seven wedges from a variety of different strategies which fit into the stabilization triangle. A new estimate by the original authors indicates that 9 wedges are now necessary, as emissions have continued to rise since the original paper on which the game was based was published.
Emissions of CO2 and other greenhouse gases have been increasing ever since the Industrial Revolution, and if the world continues business as usual, emissions will double by 2055. To prevent the worst consequences of global warming, scientists recommend freezing and reducing net global emissions immediately.
Stabilization triangle 
If global emissions of CO2 are graphed for the next 50 years, the difference between the business as usual scenario and the flat path forms a triangle. This triangle is known as the stabilization triangle. Pacala and Socolow divided this hypothetical triangle into seven stabilization wedges, which represent different measures that must be taken to reduce emissions. When speaking of different strategies to reduce emissions, the language "to reduce one wedge's worth," is often employed, and by reducing the stabilization wedge of fourteen gigatons of CO2 into seven wedges, the task is much easier to conceptualize.
Wedge strategies 
As Pacala and Socolow originally presented the wedges concept in Science, there are fifteen different wedge strategies. Regarding the specific number, Socolow says that he and Pacala didn't include all of the possibilities, but that "It was a matter of rhetoric to stop at 15. And exhaustion. There was nothing magic about 15." On the CMI website, the same strategies are presented and expanded upon in detail, and are re-organized into four categories:
- Efficiency (4 strategies)
- Decarbonization of power (5 strategies)
- Decarbonization of fuel (4 strategies)
- Forest and agricultural soils (2 strategies)
Because of the simplicity of the wedge game, it has become popular as a communication tool for global warming mitigation. It is used in a variety of arenas and by a variety of players including businessmen, politicians, teachers, and students. David Hawkins, climate director at the Natural Resources Defense Council, puts the ease of use of the Wedge Game this way:
|“||The wedges concept is sort of the iPod of climate policy analysis... It's an understandable, attractive package that people can fill with their own content."||”|
The Carbon Mitigation Initiative (CMI) permits anyone to use the game and make use of their materials, provided that they share the results with CMI. Because it is so widely accessible, it has become included in certain high school curricula. The Keystone Center has deemed the Stabilization Wedge Game to fulfill the following National Education Standards: S1, S6, LA4, LA5, C4, C5, E1, G1, G5, and WH9.
The American Association for the Advancement of Science hosted a conference for educators at the Hilton in San Francisco 2007-02-18. Collaborating with AAAS were the National Science Teachers Association and the United Educators of San Francisco (representing the National Education Association and the American Federation of Teachers). Dr. Socolow and Dr. Hotinski personally presented the Stabilization Wedge concept at the event.
The Stabilization Wedge Game is also used as a centerpiece for business seminars. Business executives played the game at as seminar held by the Sustainable Enterprise Academy at York University in Toronto.
The primary critique of the Wedge Game is that it is too simple, especially regarding the economic aspect of global warming mitigation. The materials provided by CMI only attach one, two, or three dollar signs to each wedge as a broad estimate of the expense of each option. James L. Connaughton, former chairman of the White House Council on Environmental Quality in the Bush Administration, is a critic of the Wedge Game for its oversimplicity, and he has even said that some of the numbers used by Socolow and Pacala, such as 550 ppm as a maximum allowable target for CO2, lack a scientific basis. Richard G. Richels, a senior engineer at the Electric Power Research Institute, says that the lack of economic precision in the game could create misconceptions:
|“||We have to find out what it's going to cost to make it affordable. By not including the cost issue, people come away from this thinking it will be a piece of cake. It's going to require some serious bucks. If the environment is priceless, we should be willing to pay some serious bucks to protect it.||”|
Another criticism of the game is that one of the premises, i.e. that humanity already has the tools and technologies to halt climate change, is misleading. Marty Hoffert of the New York University Physics Department claims that while the technologies are available in a technical sense, they are not available in an operational sense, and it will take a massive mobilization to make progress. Hoffert explains:
|“||...humanity had the know-how to build nuclear weapons in the late 30s or go to the Moon in the 50s. But it took the Manhattan and Apollo programs to make it so...An Apollo-like program in alternate energy is needed over a broad spectrum of mitigation technologies.||”|
In a 2010 Science article, Hoffert also suggested that 18-25 wedges may be necessary to achieve the goal, given the higher rates of emission growth that have occurred since the original study, even if no new sources were added beginning in 2010.
In June 2008, Joseph Romm argued in Nature magazine that "If we are to have confidence in our ability to stabilize carbon dioxide levels below 450 p.p.m. emissions must average less than 5 GtC per year over the century. This means accelerating the deployment of the... wedges so they begin to take effect in 2015 and are completely operational in much less time than originally modelled by Socolow and Pacala."
A final criticism is that the Wedge Game focuses on technological fixes rather than fundamentally challenging the endless growth economy that is at the heart of global climate change. The 2007 IPCC reports state clearly that economic and demographic growth are the fundamental drivers of global climate change. Yet of the fifteen wedges developed by Pacala and Socolow, only one—halving the number of miles driven by the world's automobile fleet—might be considered a "demand reduction" wedge. None of their wedges treat population reduction.
- Robert Socolow, Bulletin of the Atomic Scientists website, 27 September 2011,
- Hotinski, Roberta (2007-01). "Stabilization Wedges: A Concept & Game". Carbon Mitigation Initiative. Retrieved 2007-07-20.[dead link]
- Stephen Pacala; Robert Socolow (2004-08-13). "Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies". Science. Retrieved 2007-08-20.
- Darren Samuelsohn. "Princeton profs drive 'wedges' into policy debate". Environment & Energy Publishing. Retrieved 2007-08-17.
- "Stabilization Wedges Calculations & Data". Carbon Mitigation Institute. 2006-07-31. Retrieved 2007-08-20.
- "CSI: Climate Status Investigations (grades 9-12)". The Keystone Center. Archived from the original on 2007-09-29. Retrieved 2007-08-16.
- "Communicating and Learning About Global Climate Change". American Association for the Advancement of Science. Retrieved 2007-08-17.
- Boyce, Nell (2007-06-25). "Climate Game Gives Real Options to Save World". National Public Radio. Retrieved 2007-08-16.
- Arthur Smith (2005-12-15). "Stabilization Wedges:Comments". Retrieved 2007-08-20.
- Marty Hoffert (2005-02). "Low-Carbon Sustainable Energy in the Greenhouse Century?". Retrieved 2007-08-20.
- Hoffert, Martin I. (10 September 2010:). "Farewell to Fossil Fuels?". Science 329 (5997): 1292–1294. doi:10.1126/science.1195449. Retrieved December 2010.
- Romm, Joseph. "Cleaning up on carbon", June 19, 2008