The Wedge Game – Solving the Climate Problem By 2055

Targets For Legislative Proposals In The USA Congress Of Mandatory Cap And Trade Programs For Greenhouse Gases Emissions, courtesy of World Resources Institute (WRI) – December 8, 2008.

The top (red) line shows historical and projected carbon emissions for the USA for 1990-2050 under conditions of "business as usual." The other lines show estimated carbon emissions reductions trends for 2010-2050 under different legislative proposals.

WRI offers a high resolution image of this graph plus details about the methodology, assumptions and references that went into creating it. WRI updates the graph each year.


A World In Transition

In the brief span of about two years – between the end of 2006 and the beginning of 2009 – our global society has greatly accelerated its transformation towards a new energy economy. Considering where we were just two short years ago, those of us in the business of climate change and economic improvement solutions should be very encouraged by this progress. In late 2006, global warming and climate change science and solutions were barely on the radar of our general public and the popular media.

As we begin 2009, concrete measures to better understand our Earth’s systems together with actions to manage climate change dominate global news, global politics, and the thinking of people at all levels of our global societies. Two years ago, I would have told people that such an expansive level of activity was a decade or more away.

By about the middle of 2007, my correspondents and audiences were demanding a story far more comprehensive than scientific accounts of global warming and its impacts. People were demanding solutions. And like people everywhere, they were demanding (and offering) straightforward solutions. And most were (and remain) convinced that somehow there would be an easy-to-understand and easily implemented single solution. How do we fix this quickly? What is the single most important thing we can do? What technology do we need? How much will it cost?

Unfortunately, there is no “silver bullet” solution to drastically eliminating the bulk of our polluting greenhouse gases (GHG) emissions in a reasonably short time. However, we can solve a major part of our emissions problems beginning now and using currently available technologies.

Often described as “silver shotgun” approaches, there are solutions scenarios that comprise several concurrent actions. These are actions that make sense physically, economically, and politically – actions that might be understandable and palatable across a broad spectrum of political, economic, cultural, spiritual and other viewpoints.

In 2004, prominent carbon management researchers Stephen Pacala and Robert Socolow of Princeton University introduced the “stabilization wedges” concept for solving our climate problem for the next 50 years using current technologies. This work continues to advance, and now is a joint project of Princeton University, BP, and Ford Motor Company. The project is called the Carbon Mitigation Initiative (CMI), and it seeks practical solutions to the greenhouse gases emissions problem.



The “stabilization wedges” concept is based upon using a suite of seven low-carbon energy technologies and enhancing natural carbon sinks. The concept name comes from the “wedge” or cut in emissions depicted on a graph of carbon emissions projected for 2005 – 2055. Each “wedge” represents a carbon-cutting strategy that can grow from zero in 2005 to one billion tons of carbon emissions by 2055.

Thus, pursuing seven “wedge” strategies would cut carbon emissions by seven billion tons, keeping global carbon emissions flat for the next 50 years. Pursuing more than seven strategies would reduce our carbon emissions below today’s levels by 2055. The CMI demonstrates that at least 15 “wedge” strategies are available now, showing there is already a more than adequate portfolio of tools available today to control carbon emissions for the next 50 years.



The CMI shows opportunities for cutting carbon emissions using current technologies in combinations of actions under these headings:

Efficiency & Conservation

Increased transport efficiency
Reducing miles traveled
Increased heating efficiency
Increased efficiency of electricity production

Fossil-Fuel-Based Strategies

Fuel switching (coal to gas)
Fossil-based electricity with carbon capture & storage (CCS)
Coal synfuels with CCS
Fossil-based hydrogen fuel with CCS

Nuclear Energy

Nuclear electricity

Renewables and Biostorage

Wind-generated electricity
Solar electricity
Wind-generated hydrogen fuel
Biofuels
Forest storage
Soil storage

The CMI provides briefs showing how GHG emissions reductions are calculated for each opportunity in this list. The briefs include commentaries on the pros and cons of each technology and how they interact with each other. The numbers in these commentaries should be useful to those wishing to understand the dimensions of combatting GHG emissions.

The CMI has produced a “Teachers Guide to the Stabilization Wedge Game.” This is a team-based exercise in which players build a portfolio of stabilization strategies and assess their impacts and costs. Those interested in explanations of our climate and carbon problem – and the relative contributions and costs of solutions using the strategies above – might want to examine this guide and its associated resources.

A significant feature of the “wedge” concept and game is that people may choose their preferred combinations of strategies from the above list, and reject strategies that might be less palatable for various political, economic or other reasons. For example, if you do not like current-technology nuclear or coal-fired electricity as a part of the suite of solutions, you can select a balancing alternative from the list of 15 opportunities. You might also consider the extra costs and benefits of substitututing compensating amounts of current-technology wind- and solar-generated electricity, for example.