The important role of state policy in cutting carbon emissions

Using a breadth of datasets, researchers modeled how states’ clean energy goals might evolve under state-led action versus federal support.

June 12, 2025 Rachel Metea

Image: Rob Davis, AgriSolar Clearinghouse, CC BY 2.0

State-led policy can cut emissions at roughly the same costs as federal policy, but the technologies used will vary by region, according to a study published in Nature Communications.

The paper, “State-led climate action can cut emissions at near-federal costs but favors different technologies,” said state and other local policy can often better address a patchwork of regions with differing needs, beliefs, environments and infrastructures.

According to the study, state-level energy and climate legislation has grown over the last decade, and academic interest in environmental policy at the state level is nearly at a 30-year peak.

The study noted that advocacy groups are calling upon “New Climate Federalism,” a multi-tiered government collaboration framework that recognizes the strengths of each government level. However, the study said that the return of the Trump Administration will greatly reduce the likelihood of passing climate-friendly energy policy at the national level.

“We have two major political parties with vastly different climate objectives,” the authors noted. “One party advocates for existing renewable energy tax incentives, forthcoming vehicle emissions mandates from the Environmental Protection Agency, and the United States’ participation in the Paris Agreement, while the other explicitly seeks their removal.”

Additionally, federal action on climate change is volatile and may shift abruptly with changes in administration, the study said. “Further federal action in the near-term is unlikely,” the researchers added.

For this reason, a piecemeal approach using the states’ strengths may offer the most resilient and plausible pathway for further reductions in emissions, the study said.

With the energy transition, the researchers said, the federal government may be framed as fragmented, and “perhaps supplementary to the states.”

In contrast to the uncertainty of federal support, over two-thirds of the Americans believe the United States should prioritize developing alternative energy sources, according to the study.

Legislation at the state or more local level can be designed to play to both a region’s strengths and needs, the authors said.

For example, the researchers said they were unable to employ a one-size-fits-all strategy for states with deep-carbonization constraints to meet net-zero goals in the state-led scenario. California and the Northeast, for example, both achieved their net-zero goal using the same technology, but to do so, the Northeast added solar and battery resources, along with electric heat pumps, while California imported Southwestern solar and wind.

Channeling energy and climate policy to subnational groups, such as state and local lawmakers, taps their institutional capacities in more effective ways than the weaknesses of the top-down approaches at the federal level, the authors said.

The researchers identified states that are most likely to pursue net-zero emissions by 2050 using a set of political indicators, such as whether they had a state-level renewable portfolio standard, their political leanings and any existing energy and climate policy. Using energy data from across sectors, they estimated the cost of decarbonization and the most likely technology they would use to get there.

Political score used to identify net-zero ambition states States shaded blue are included as net-zero states in the State Action scenario, while those shaded red are excluded.

The study found state-level and federal-level efforts were roughly the same in cost, but would likely result in the adoption of different decarbonization technologies across regions.

For regions with low involvement in decarbonization efforts, with the Southwest in particular, the researchers found a national-led plan could lead to a generation portfolio with increased solar, wind, battery and biomass generation. Under a state-led plan, without incentive to reduce emissions, the researchers found more natural gas and coal would likely be deployed in the region.

The researchers found a “substantial” increase in overall electricity generation in regions committed to decarbonization under state-led scenarios compared to federal-led efforts.

Differences in CO2-eq emissions by sector. Positive values indicate higher emissions in the national action scenario, while negative values indicate higher emissions in the state action scenario.

“Broadly, the outcomes of these two regions in the state-led scenario demonstrate the need for an energy policy designed to play to both a region’s strengths and needs,” the researchers said.

The researchers found that in the federal-led scenarios, in Texas and the Southeast, a moderate national emission constraint is sufficient to motivate added bioenergy with carbon capture and storage, solar, and wind generation. “The substantial addition of these technologies under federally-led decarbonization changes the involvement of these regions entirely, turning politically reluctant regions into significant contributors to climate mitigation,” the study said.

The research received financial support from the Alfred P. Sloan Foundation.

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