What Bill Would Do, Who's Affected

Amid concern about global climate change, the state Legislature gave final approval Thursday to AB 32, a bill to combat global warming.

What would the bill do?

AB 32 requires California's Air Resources Board to develop a program to reduce the state's greenhouse gas emissions to 1990 levels by 2020, a cut of about 25% from today's levels. Reductions will be required starting in 2012.

What are greenhouse gases?

Greenhouse gases, which trap heat in the atmosphere, are identified in the bill as carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

Where do they come from?

Globally, power plants and office buildings produce about two-thirds of greenhouse gas emissions, and cars and trucks produce much of the rest. In California, the percentage from mobile sources is slightly higher, both because we drive so much and because statewide energy efficiency standards exist for buildings but not vehicles.

What businesses would be affected?

Utility plants, oil and gas refineries, factories and cement kilns, among other major emitters of the gases.

How can the state reach 1990 levels?

Experts say emissions would have to be reduced by 174 million metric tons. The approaches for achieving those reductions could include mandatory limits on emissions from utilities, cement companies and other heavy industries; energy efficiency measures; and the establishment of a market-based emissions trading program.

What are the major challenges to meeting the goals?

The U.S. Environmental Protection Agency has declined to support a California tailpipe emissions-control law, which is being challenged in court by automakers. Moreover, the EPA has chosen not to classify greenhouse gas emissions as pollutants, a decision being challenged in court by the Sierra Club and several states.

If California were to meet its emission-reduction goal, what would the effect be on the state's climate?

Unless other states and nations follow suit, there would be little effect, according to Ken Caldeira, a climate scientist at the Carnegie Institution's department of global ecology at Stanford.

"While it's important for the United States and California to show leadership, the actual effect on California's climate of reducing the state's carbon dioxide emissions will be negligible," Caldeira said. "It would be an altruistic gift from California to the rest of the world."

But Dan Kammen, who heads UC Berkeley's Renewable and Appropriate Energy Lab, called the legislation a "big step because every trend until now has been toward ecological devastation, and this reverses that." He said there would be a multiplier effect because California buys 25% of its power from elsewhere and would require much of that power to be clean or its greenhouse emissions to be traded in a market-based cap-and-trade program.

Will consumers pay more or less for energy as a consequence of the state's efforts?

Experts disagree.

Kammen said costs would go down. He co-authored a 2004 study that found $20 billion in consumer benefits over the next few years from increased use of wind power and energy efficiency measures. But other researchers say reducing greenhouse gases just from power plants, which are major greenhouse gas emitters, will create costs in the billions of dollars. Sally Benson, a UC Berkeley geologist who is testing carbon sequestration technology, said studies show possible increases in electric bills of 15% to 20%.

Can the 2020 deadline be changed?

The bill allows the governor to extend the deadline by as much as one year, "in the event of extraordinary circumstances, catastrophic events or threat of significant economic harm." Of course, the Legislature could always pass a new bill to change the law.

janet.wilson@latimes.com

marla.cone@latimes.com

Times researcher Scott Wilson contributed to this report.