Proponents and opponents of capping carbon-dioxide emissions in New Mexico crammed the auditorium Monday at the Willie Ortiz Building, waiting for their chance to testify before the Environmental Improvement Board.

The board is considering a petition by the nonprofit New Energy Economy and several co-sponsors to cap greenhouse-gas emissions at 25 percent below 1990 levels in the next decade. The petition specifically targets any industry that emits more than 10,000 metric tons of carbon dioxide per year. The cap would impact coal-fired power plants, oil and gas producers, cement and asphalt plants and other companies that need state air-quality permits.

Monday's packed auditorium for the Environmental Improvement Board hearing was a testament to the big public interest in climate change and the bitterly divisive politics behind the science.

Proponents in the health and environment sector say the emissions cap is needed to mitigate long-term damage from climate change. The scientists they listen to say greenhouse gases from human industrial activity are causing sea levels to rise, melting polar ice caps and increasing temperatures and droughts in Western states such as New Mexico. They believe switching to "clean energy" in the form of solar, wind and geothermal will create jobs and, in the long run, save consumers money because the cost of fossil fuel, a nonrenewable resource, will go up as supplies run out.

Katherine Campbell, a Los Alamos National Laboratory statistician and president of the League of Women Voters New Mexico, said the state needs to adopt an emissions cap now and not wait for Congress. "Change is never easy, but inaction is not a choice," she told the board.

Opponents of the emissions cap are split. Some say studies that show humans are causing global warming are based on junk science. They tout scientists who've said climate change is associated with other factors.

Others oppose the petition because they say a cap on carbon-dioxide emissions in New Mexico alone will jack up the cost of electricity to consumers and chase out businesses — and won't make a dent in climate change. They believe the emissions cap will hurt an already struggling economy in a state dependent on revenues from the oil and gas industry. They think New Mexico should wait until a federal cap on greenhouse-gas emissions is passed.

The public had six hours to testify before the board Monday. Technical testimony and further public testimony will be accepted later in the spring. The Environmental Improvement Board also has received more than 300 pages of written testimony from the public.

Michael L. Johnson, a retired Conoco executive now living in Santa Fe, opposes the New Mexico emissions cap. In written commentary to the board, Johnson says he has the experience and education to understand climate change — he has a master's degree from Rice University in geochemistry and paleoclimatology and another master's in finance from the Massachusetts Institute of Technology.

"There is no compelling case that capping CO2 would result in any significant economic improvements in employment or the economy," Johnson wrote. "There is no practical case for climate impacts if New Mexico were to ... cap CO2."

Public Service Company of New Mexico, the state's largest power utility, opposes the petition for different reasons. Most of its electricity is generated by coal-fired power plants. In documents opposing the petition, PNM recognizes climate change "as the most important environmental challenge facing the nation. ... PNM supports the conclusion of the International Panel on Climate Change that the Earth is warming and the human activities are a major contributing factor."

The company said it is working to increase its renewable energy power sources, but in the meantime it is obligated to keep customer electricity rates as low as feasible. A cap would have an "adverse impact on PNM customer rates," the company said.

New Energy Economy maintains that the Environmental Improvement Board, an unelected body appointed by the governor, has authority under existing law to implement statewide limits on greenhouse-gas emissions.

Industry groups, some state lawmakers and others disagree. More than a dozen opponents have filed a lawsuit challenging the board's authority.

Contact Staci Matlock at 986-3055 or smatlock@sfnewmexican.com.