A pragmatic approach to deep reduction in U.S. CO2 emissions

It is now widely accepted that CO₂ and other heat-trapping gasses released into the atmosphere by human activities are driving a global temperature rise that, if unchecked, could result in severe damage to natural and human systems [1]. The urgency of deep decarbonization of the U.S. economy is now clear and several renewable energy technologies are approaching cost parity with fossil fuels. However, debates around the requisite rate of reduction, and the form of regulations that can achieve those reductions fairly and cost-effectively have resulted in near inaction. Typical studies of the GHG reduction pathways rely on multiple sets of assumptions including a fixed trajectory for reduction in GHG emissions (a ‘glide-path’) designed to achieve a chosen representative concentration pathway (RCP, the actual atmospheric concentration of GHG) [2, 3], costs of technology alternatives and some form of model for technology selection and deployment. These models seek to minimize total cost (net of taxes and incentives) within other constraints [4-7]. As a result, such models are highly informative as to what technology pathways might be effective in meeting the stated goals (given the model assumptions) but are far less informative in regard to how precisely a given regulatory concept – which cannot ‘know’ the future or change personal preferences – will steer technology choices along a preferred pathway.