Two Virginia environmental groups are entering the legal fray over whether the U.S. Environmental Protection Agency can regulate greenhouse gases in an effort to slow climate change.

A motion to intervene in a federal lawsuit was filed Thursday by the Southern Environmental Law Center on behalf of Wetlands Watch, a Norfolk-based group concerned about rising sea levels.

The legal move comes one month after Virginia Attorney General Ken Cuccinelli filed court papers asking the EPA to reconsider its finding that carbon dioxide and other emissions contribute to global warming.

Cuccinelli has argued that recently disclosed e-mails suggest the EPA relied on flawed data and, in some cases, falsified information.

The Southern Environmental Law Center called Cuccinelli's action "an unwarranted stall tactic, and a dangerous distraction from grappling with the damaging impacts of climate change."

At stake, among other things, is the EPA's authority to regulate greenhouse gas emissions from new automobiles. The agency is also taking other steps to enforce the Clean Air Act, such as toughening federal guidelines on ozone emissions.

A recently announced proposal to reduce the maximum allowed emissions level to 70 parts per billion could mean that the Roanoke Valley will soon exceed the standards.

The complex lawsuit, filed in the U.S. Court of Appeals in Washington, dates to 1999, when the EPA refused to set standards for automobile emissions at the request of clean-air advocates. The case went to the U.S. Supreme Court, which ruled against the EPA in 2007.

The EPA then conducted research and public hearings before determining, late last year, that greenhouse gases endanger public health.

That in turned sparked another court challenge by the Coalition for Responsible Regulation, which argued that the EPA had overstepped its authority. Three states, including Virginia with Cuccinelli's finding, have joined the case in support of the coalition.

Thirty-two other states have filed motions to intervene, with 18 siding with the EPA, according to SELC attorneys. Numerous private groups and even some members of Congress are also seeking to enter the case.

At a news conference last month, Cuccinelli said internal e-mails and documents from a British climate research center cast doubt on the EPA's findings and provided the basis for his attempt to block federal regulation of greenhouse gases.

Environmental groups argue that those concerns are outweighed by years of research supporting the EPA's position.