Environmental groups filed a lawsuit today against a major component of California's landmark cap-and-trade program for greenhouse gases.

The suit from Citizens Climate Lobby and Our Children's Earth Foundation alleges that the plan violates state law by allowing companies to meet part of their emission-reduction obligations with credits purchased from outside the program.

The program lets businesses use offsets for up to 85 percent of their total required reductions under the cap, which runs from 2013 to 2020. Yesterday, the state Air Resources Board announced it would delay the first auction of allowances from this August to November, citing unpreparedness (ClimateWire, March 28).

The suit, filed in San Francisco Superior Court, argues that offsets are inherently uncertain to result in greenhouse gas emissions reductions above what would have occurred without the incentive to curb them. California has four different offset guidelines, covering reductions from livestock farms, forests, urban forests and ozone-depleting substances.

Also supporting the suit, but not party to it, is the watchdog group Public Employees for Environmental Responsibility.

PEER Executive Director Jeff Ruch said two plaintiffs, U.S. EPA enforcement attorneys Laurie Williams and Allan Zabel, asked him to help publicize the suit. The married couple have been vocal on emissions policy in the past, arguing in 2009 that a market-based program would be more vulnerable to scams than a carbon fee or tax (ClimateWire, Feb. 24, 2009).

Air Resources Board spokesman Stanley Young said the lawsuit would run counter to the environmentalists' ultimate goal of limiting emissions that spur climate change.

"It is disappointing that a group who claims to understand the pressing severity of climate change is seeking to put up roadblocks in California's effort to address it," he said.

The program meets all requirements of A.B. 32, the 2006 law that set an emissions reduction target of 1990 levels by 2020, he said. "It will cost-effectively deliver major reductions in greenhouse emissions," he said, "and serve as a model for urgently needed national and international efforts."