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Energy & EnvironmentPrice signalPositive

Regional Greenhouse Gas Initiative (RGGI) — Cap-and-Trade Evaluation

Resources for the Future / Acadia Center / multiple academic evaluations · Northeastern United States (12 states) · 2009

Summary

RGGI is the longest-running cap-and-trade program in the United States and the most rigorously evaluated subnational climate policy in the world. The empirical record demonstrates that a regional, electricity-sector-only carbon market can deliver substantial emissions reductions without economic damage and with positive secondary effects (lower air-pollution health impacts, energy-efficiency program funding). The program's significance for civic experimentation is twofold. First, RGGI is a working demonstration that subnational jurisdictions can implement effective climate policy when federal action is unavailable — a finding with broad implications for climate policy design under conditions of federal political constraint. Second, the RGGI evaluation literature has provided perhaps the cleanest available estimates of carbon-pricing effectiveness in a real-world implementation: emissions declined, prices didn't spike, generation didn't leak catastrophically, and revenue was productively recycled. These results have been cited extensively in subsequent state and national climate-policy debates and remain among the strongest available evidence on the practical effectiveness of cap-and-trade design.

Research question

"Does a regional cap-and-trade system for electricity-sector CO2 emissions reduce emissions cost-effectively, and what are the broader economic effects on consumers, generators, and state economies?"

Methodology

Intervention

The Regional Greenhouse Gas Initiative began in 2009 as the first mandatory cap-and-trade program for greenhouse gases in the United States. Participating northeastern states (initially 10, now 12) set a declining cap on CO2 emissions from electric power plants and required generators to purchase emission allowances at quarterly auctions. Revenue from auctions (over $7 billion to date) was returned to participating states for energy-efficiency, renewable-energy, and bill-assistance programs.

Assignment

Quasi-experimental — difference-in-differences comparing electric-sector emissions, electricity prices, and economic outcomes in RGGI states to comparable non-RGGI states; multiple independent evaluations with somewhat differing estimates

Sample size

Twelve participating states (CT, DE, ME, MD, MA, NH, NJ, NY, PA, RI, VT, VA) covering approximately 70 million people and electric generation across the region

Primary outcome

Electricity-sector CO2 emissions; electricity prices; state economic outcomes (GDP, employment); emissions leakage to non-RGGI states

Effect estimate

RGGI-state electricity emissions declined by approximately 50% between 2009 and 2020 — substantially faster than non-RGGI state declines (~30%) and faster than the program's own declining cap had required. Independent econometric studies attribute 20-30% of the decline directly to RGGI policy. Electricity prices in RGGI states grew more slowly than in non-RGGI states. Modest leakage of generation to non-RGGI states was detected but offset by other compliance pathways.

Decision

RGGI has been a foundational model for subsequent US state-level climate policy. California's cap-and-trade program (operational since 2013), Washington State's Climate Commitment Act (2023), and Pennsylvania's (intermittent) RGGI participation have all drawn on the RGGI design. The cumulative auction revenue distribution model has been particularly influential.

Result

Positive

RGGI-state electricity emissions declined by approximately 50% between 2009 and 2020 — substantially faster than non-RGGI state declines (~30%) and faster than the program's own declining cap had required. Independent econometric studies attribute 20-30% of the decline directly to RGGI policy. Electricity prices in RGGI states grew more slowly than in non-RGGI states. Modest leakage of generation to non-RGGI states was detected but offset by other compliance pathways.

Evidence strength

Moderate

Quasi-experimental design with replication support.

Replication status

Replicated

Institution

Resources for the Future / Acadia Center / multiple academic evaluations

Location

Northeastern United States (12 states)

Year

2009

Policy area

Energy & Environment

Mechanism

Price signal

Other trials of this mechanism

Cite this entry

Resources for the Future / Acadia Center / multiple academic evaluations. (2009). Regional Greenhouse Gas Initiative (RGGI) — Cap-and-Trade Evaluation. The Experiment Society Registry. Retrieved from https://www.experimentsociety.org/registry/regional-greenhouse-gas-initiative (primary report: https://www.rff.org/publications/reports/regional-greenhouse-gas-initiative-2020/)

Citation network

Cited by 1 other entry in the registry

Cross-references

Adjacent experiments — same domain, parallel pilots, or alternative mechanisms.

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