Sen. Dianne Feinstein offered a new Democratic outline Thursday night of a plan to attack global warming in the next session of Congress -- and put political opponents on the defensive headed into the fall campaign season.

In a speech to the Commonwealth Club in San Francisco, California's senior senator unveiled a legislative package she intends to introduce when Congress reconvenes in January. The bills would require carmakers to improve mileage and would coax power producers to meet emission standards, while extending California-style green-technology programs nationwide.

"There now is a scientific consensus that global warming is happening and we can't stop it," Feinstein said during an interview. "The effort we have to make is to restrict it."

Parts of her speech touched on legislation already introduced, such as a requirement that cars, sport utility vehicles and light trucks get another 10 miles per gallon within 10 years.

But Feinstein also called for new provisions, in particular a proposal to bring agriculture and forest managers into a market system for greenhouse gas emissions known as "cap and trade." This would allow farmers and landowners who plant trees or convert crops into bio-fuels to earn emission credits that could be sold to companies that exceed emission limits.

That could help alter the politics of the climate change debate in farm states and perhaps in some corporate circles, although coal producers have made clear that they will fight any program along the lines that Feinstein is proposing.

Internationally, the program would put the United States in a position to lead, Feinstein said, and would help coax countries such as China and India to hold down their emissions, too, despite fast-growing economies.

The goal would be to keep global temperature increases to a manageable 1 or 2 degrees by the end of the century. To do so by 2050, she said, the United States would have to cut carbon dioxide emissions to levels 70 percent below those of 1990.

Without such measures, she said, the global temperature could rise by maybe 9 degrees. In that scenario, 3 of every 5 species would die, the sea would rise by 2 feet, massive floods would hit every 10 years, and the state's drinking water supply would be in jeopardy, Feinstein told the audience.

Political analysts said it's hard to gauge chances for global warming legislation in the next Congress. Former Vice President Al Gore's movie, "An Inconvenient Truth," might have raised public appetite for action, they say. But the Bush administration and Republican allies on Capitol Hill have shown little enthusiasm for measures they suggest are unnecessary and potentially damaging for job growth and energy independence.

Coal producers maintain Feinstein's approach would "solve the so-called global warming problem by rationing the use of coal, essentially taxing the use of coal," said Luke Popovich, spokesman for the National Mining Association, which represents coal interests in 38 states.

Feinstein's proposals aren't the boldest to come forward in recent months. But environmental groups say there is a growing consensus that something needs to be done.

"People are waking up to the increasing threat of higher temperatures to the planet and impact that will have," said Brenda Ekwurzel, climate scientist at the Union of Concerned Scientists. "People also are realizing if we delay action on starting to reduce our heat-trapping emissions, then we will have lost precious time we can't get back."

Moves by California and a coalition of Eastern states to rein in greenhouse gas emissions also are changing the policymaking dynamic.

In California, for instance, UC Berkeley experts recently issued a study suggesting that clean-energy and other global warming policies actually boost economic activity, a theme championed by Republican Gov. Arnold Schwarzenegger.

Controversial caps on industrial emissions would be more effective, and perhaps more politically palatable, if incorporated into a carefully designed "cap and trade" system, said Alex Farrell, a UC Berkeley assistant professor of energy and resources who has studied market-based environmental regulations.

Details are critical, however, and Feinstein has yet to work those out. For instance, one key issue involves how the carbon-emissions credit-swapping would be monitored, to be sure that actual reductions are implemented.

Such systems have been tested before and shown to be "very effective in the United States at protecting human health and at very reasonable cost," Farrell said. "This is not a panacea, but greenhouse gas emissions are a good case for this."

Feinstein told her Commonwealth Club audience that global warming will be her top environmental priority in the coming Congress. She portrayed California's innovation-based economy as the pacesetter for the nation.

"With every challenge comes a new opportunity, and California is well positioned to take advantage of a new low-carbon economy," she said. "The state has already begun to reap the economic benefits of cleaner, greener and more efficient technologies and standards."

Speech highlights

Main points of Sen. Dianne Feinstein's global warming talk:

-- Action now can limit global temperature increases to 1 or 2 degrees by 2050. Without action now, there will be catastrophic increases on the order of 5 to 9 degrees.

-- A 70 percent cut in carbon dioxide emissions below 1990 levels could stabilize the atmosphere

-- Cars, SUVs and trucks account for one-third of carbon dioxide emissions and should be forced to improve mileage by 10 mpg by 2017.

-- Power plants and major emitters of greenhouse gases should have to cap emissions or obtain credit from other companies that have lowered their emissions below target levels. Farmers could obtain credits by planting trees or tilling land less often. Protecting rain forests in developing countries also could generate credits.

-- Parts of California's program to encourage energy-efficient construction and renewable technologies should be incorporated into a national program. The program should require that utilities meet a portion of energy demand with clean energy sources like wind and solar.

Source: Speech to the Commonwealth Club