SAN FRANCISCO — A coalition of private companies and government agencies is launching a grassroots marketing campaign to persuade more Americans to help combat global warming by using energy-efficient light bulbs.

The 18Seconds movement is aimed at getting Americans to replace electricity-wasting incandescent bulbs with compact fluorescent bulbs that are up to five times more efficient and last several times longer.

The campaign — named for the average time it takes to change a light bulb — is scheduled to launch Thursday at the Tech Museum of Innovation in downtown San Jose.

The coalition includes Yahoo Inc., Wal-Mart Stores Inc., Environmental Defense, U.S. Environmental Protection Agency, Energy Department, U.S. mayors, retailers, religious organizations and conservation groups.

The campaign’s goal is to increase awareness of energy-efficient light bulbs as a way to slow global climate change, organizers say. If every American swapped just one bulb, advocates say, the country could save $8 billion in energy costs and eliminate 2 million cars worth of greenhouse gas emissions.

“It’s a huge savings for the country and consumers, and it gets people thinking about what can they do,” said Lawrence Bender, producer of “An Inconvenient Truth,” Al Gore’s documentary on global warming.

The coalition plans to create a series of “hip and cool” public service announcements featuring Hollywood actors, sports stars and other celebrities to play on Internet video sites and at movie theaters, Bender said.