San Franciscans will be able to purchase absolution for some of their environmental sins under a new city program that will use the funds to reduce climate changing emissions from government work and from local businesses and residents.

Activities powered by fossil fuels or bio-fuels, such as driving, flying or building a bridge, change the Earth’s weather by increasing the amount of heat-trapping carbon dioxide in the air — a phenomenon scientists call global warming.

An array of new businesses have recently begun selling what’s known as carbon offsets, which reduce the effects of carbon dioxide emissions by paying for projects that fight global warming.

Mayor Gavin Newsom announced Tuesday that The City will create its own carbon offset program, saying it will be the first-ever city-based carbon offset program that funds only local green activities.

“It may not seem like a huge thing,” Newsom said, “but it’s really an innovative program.”

The City will initially pay $80 to one of three local nonprofits for every ton of carbon dioxide produced whenever a city employee takes a work-related flight, according to Environment Director Jared Blumenfeld. He said the program could be expanded to include car travel.

Offsets that can be bought on the Internet for as little as $8 a ton were described by Blumenfeld as scams.

The City aims to call for proposals in one year from other groups hoping to receive funding through the program, and it will begin selling carbon offsets to local businesses and residents, according to Blumenfeld.

San Francisco nonprofits expected to initially receive funding through the carbon offset program include Grid Alternatives and San Francisco Biodiesel Cooperative, as well as Ecology Action, which is based in Santa Cruz.

Ecology Action is a Santa Cruz-based group that has helped hundreds of San Francisco businesses reduce their energy use, according to Ecology Action Vice President Mahlon Aldridge.

Aldridge said the extra money could be used to provide new rebates on energy-saving devices.

Alex Farrell, a UC Berkeley energy professor, said many offset programs promise more than they deliver, but he said The City’s project was very interesting.

“There are two key things for solving climate change — a new energy system is number one, and stopping deforestation is number two,” Farrell said.