PNNL

Abstract

The potential impact of climate action from non-national actors—including states, cities, businesses, and others—in delivering higher global climate ambition may be much greater than has been generally realized. Recently expanded sub-national action in the United States provides a test for how diversification of climate action including these actors can accelerate emissions reductions. We aggregated U.S. state, city, and business commitments within an integrated assessment model (GCAM) to assess how a national climate strategy can be built from subnational actions, and what these actions are currently on track to deliver in the U.S. We find that existing sub-national com20 mitments from states, cities, and some businesses could reduce U.S. emissions 25% below 2005 levels by 2030, and that enhancing actions by these non-federal actors alone could reduce U.S. emissions up to 37% below 2005 levels by 2030. We show that these actions can provide a stepped23 up basis for additional federal action that could reduce emissions by 49%—a pathway consistent with 1.5ºC. Our analysis demonstrates sub-national actions can lead to substantial near-term re ductions; moreover, it shows that such actions can build a basis for higher ambition and more effective implementation at the national level. Approaches that root actions in local and regional processes will be essential for all countries as they develop new nationally determined contribu28 tions under the Paris Agreement.