Insights on Emissions Reduction among U.S. States

A Report by the Clean Resilient States Initiative

From 2005 to 2018, the United States reduced its carbon dioxide emissions from the energy sector by 12 percent, but the national average masks wide variation in performance across states. Declines in emissions were dramatic in some states; in others, emissions changed little or even grew. What explains this variation? What might policymakers learn from the states reducing emissions?

To answer these questions, the CSIS Energy Security and Climate Change Program investigated state policies that aim to reduce emissions or boost low-carbon energy. This report focuses on 16 U.S. states that are representative of the country. The authors were interested in the following questions:

  • Which states reduced emissions the most, and what drove those reductions?
  • Did emissions fall across the energy system, or were they concentrated in some sectors?
  • Was the reduction in emissions a product of policy, market forces beyond the control of policymakers, or exogenous factors?
  • What policies did different states adopt to lower emissions and support low-carbon energy sources? Is there evidence these worked?
  • What lessons can be learned about designing policies to reduce emissions?
  • How have interstate collaborations and federal policy complemented or inhibited state action?

The first section of this paper describes facts about greenhouse gas emissions in the 16 states sampled: where they fell, by what magnitude, etc. The second assesses how specific policies might have affected these outcomes. The analysis here focuses on the power sector, where the biggest reductions were made, and policy instruments that supported decarbonization of the power sector. The third section looks at equity and environmental justice. A final section presents the report’s main conclusions.

This report is made possible by the Sloan Foundation.

Morgan Higman

Morgan Higman

Former Fellow, Energy Security and Climate Change Program

Stephen J. Naimoli

Nikos Tsafos