Co-directors Steve Pacala and Rob Socolow lead the effort to synthesize CMI results for a wider audience and steer CMI research toward broad and timely questions.

Early on in the project, we committed to a third-year goal of producing a comprehensive assessment of proposed solutions to the carbon and climate problem, as well as our own recommendations. Toward this end we are now writing a document that addresses the feasibility of different strategies in cutting emissions through 2050, using the concept of a “stabilization wedge.”

The Stabilization Wedge

Our document is a response to an argument in the scientific and popular press over whether currently known low-emissions technologies could displace enough CO2 emissions from the global energy system to mitigate future climate change. On one side are scientists who look far into the future and call for investing in research and development for “magic bullet” technologies that would solve the problem in one fell swoop. On the other side are scientists who maintain that existing technologies can be scaled up to tackle the problem gradually if action is started now.

Our approach focuses on the carbon emissions problem from now through 2050. Between now and that time, global emissions are typically projected to double from 7 to around 14 billion tons of carbon per year. An alternative path would keep emissions at current levels, cutting out a “Stabilization Wedge” of emissions equal to 175 billion tons of carbon over 50 years. This wedge is represented by the central pink triangle in the diagram above, and grows from zero today to replacing 7 billion tons of carbon per year in 2050. The alternative path is consistent with some of the lower stabilization targets under discussion today; it most resembles stabilization at 500 ppm.

We divide this wedge up into seven “slices,” which represent activities that grow from nothing now to preventing 1 billion tons of carbon from entering the atmosphere per year in 2050. We ask: Can existing technologies provide the slices to build this wedge? Our estimates indicate that scaling-up technologies and programs that exist today could provide more than enough slices to replace this wedge of emissions, while at the same time keeping pace with the world’s energy needs. The strategies we believe could provide one or more slices include:

  1. Energy efficient technologies
  2. Replacing coal use with natural gas
  3. Zero-carbon electricity from solar cells, wind  turbines, and nuclear plants
  4. Zero-carbon fuels from biomass
  5. Carbon capture and underground storage
  6. Biological storage

This simple wedge model is proving to be a useful focal point for our internal objective of an integrated research plan.