"Wedges": Early mitigation with familiar technology

This chapter focuses on the Stabilization Triangle with respect to global carbon management. The Stabilization Triangle pays attention to the choice between two paths for the next fifty years: a path consistent with stabilization at less than double the pre-industrial CO₂ concentration (500 ppm), and a path that is likely to lead to tripling of that concentration (850 ppm). If the world is willing to accept a tripling of the pre-industrial atmospheric CO₂ concentration, significant carbon mitigation can be delayed for most part of the next fifty years. If the world is to be put on a path to avoid a doubling, however, a monumental mitigation effort needs to be initiated now. To convey the magnitude of the effort, the chapter introduces the "wedge" as the unit of mitigation. A wedge is an activity that would create 1 GtC/y of carbon emission reductions in 2054, relative to a world unconcerned about global carbon emissions. To pursue 500 ppm stabilization, the task for the next fifty years is to achieve about seven wedges by avoiding about 175 billion tons of carbon emissions.