Virginia can’t withdraw from a multistate initiative designed to reduce greenhouse gas emissions unless the Legislature agrees to it, a judge has ruled, dealing a blow to Gov. Glenn Youngkin’s efforts to exit the compact.

The ruling, issued Monday by retired Judge C. Randall Lowe in Floyd County, said Virginia’s Air Pollution Control Board exceeded its authority when it voted last year to exit the Regional Greenhouse Gas Initiative.

The Regional Greenhouse Gas Initiative is an effort by 12 mid-Atlantic and Northeast states to reduce power plants’ carbon emissions. Participating states require plants of a certain generating capacity to purchase allowances to emit carbon dioxide, a greenhouse gas that contributes to global warming.

Virginia joined the compact in 2020 when it had a Democratic governor as well as Democratic control of the Legislature. In 2021, Youngkin, a Republican, won election as governor but one or both legislative chambers have remained under Democratic control for the entirety of his term.

Youngkin has said Virginia’s participation in the cap-and-trade program amounts to a hidden tax on Virginians’ energy bills.

His spokesman, Christian Martinez, said Wednesday that the state will appeal the judge’s ruling.

“Governor Youngkin remains committed to lowering the cost of living for Virginians by continuing to oppose the Regional Greenhouse Gas Initiative, which fails to effectively incentivize emission reductions in the Commonwealth,” he said in a written statement.

Shaun Kenney, a spokesman for Republican Attorney General Jason Miyares, also expressed disappointment in the judge’s ruling in a written statement, saying: “We look forward to defending the commonsense repeal of this counterproductive program on appeal.”

The State Corporation Commission has estimated the typical monthly bill could increase by $2 to $2.50 for the years 2027 to 2030.

Last year, before the pollution board voted to end participation in the compact, Dominion Energy, the state’s largest utility, estimated that it had incurred about $490 million in compliance costs from the initiative and recovered about $267 million from customers.

Virginia House Speaker Don Scott, a Democrat, praised the judge’s ruling, calling it “a win for all Virginians, their wallets, and our environment. Programs funded by RGGI have helped Virginians cut household energy costs, helped protect communities from floodwaters, and have been critical in the fight to cut pollution and address climate change.”