The US government may have refused to throw its weight behind efforts to reduce greenhouse gas emissions, but Americans are increasingly acting on their own initiative.
In the latest in a series on changing US attitudes to global warming, the BBC's Sam Wilson profiles three grassroots ventures in the state of California.
California's generous endowment of sunshine gives it a golden opportunity to exploit solar power, but the town of Sebastopol, north of San Francisco, has been particularly energised.
Sebastopol swimming pool's pumps are powered by its solar panels
Its goal is to install one megawatt of solar power production across the town - equivalent to decking the roofs of 500 average-sized homes with solar panels.
It is over a third of the way there, with 380kW-worth of panels fitted so far on local government buildings, businesses and homes. One of the most eye-catching adorns the roof of the town's open-air swimming pool.
Sebastopol's Mayor Sam Pierce describes it as a "very aggressive effort, by both the city and the community", to tackle global warming.
His city council has also set itself a target of reducing its own emissions by 42% over a 10-year period - the most ambitious target in the US and far ahead of those demanded by the Kyoto Protocol.
Mr Pierce - whose Green Party has held a majority in Sebastopol for six years - says the pressure for action is definitely bottom-up.
"Our community is very tuned in, very well informed on climate change, and wants to take action," he says.
"So, as a result, the policy-makers are very aggressive, and find ways to satisfy that demand in the public."
The 42% target comes from closely audited assessments, says the city manager, David Brennan, and should therefore be achievable.
The city is improving energy efficiency in heating and lighting in council buildings, and has bought five hybrid vehicles when replacing its fleet, including three police cars.
The officials are disappointed that President George W Bush has refused to set nationwide emissions reduction goals, but hopes Sebastopol's efforts will be replicated at the local level elsewhere.
"If there's any silver lining to what I would call the debacle of the Bush regime, it's that it demonstrated to local jurisdictions that it's essential that they find local solutions," Mr Pierce says.
"The nationals aren't going to do it. But we as a community are going to demonstrate to the rest of the country what can be done."
"You do what you can, then find a megaphone."
BIOFUEL OASIS, BERKELEY
Biofuel Oasis is an all-female co-operative in Berkeley, which serves as a retail outlet for biodiesel.
The fuel is converted from waste cooking oil from local restaurants, and sold to customers willing to pay a little more than the regular diesel price.
Eric, one buyer of biodiesel, says it 'feels better in my soul'
The six partners in the enterprise take turns to open up in the evenings, where they do a brisk business, often to regular customers. Their occasional clients include country music star Willie Nelson, who fills up his tour bus when passing through.
It is a varied clientele, says one of the partners, Gretchen Zimmermann.
"I'd say they're more white-collar than blue-collar - anything from hippies to pretty normal looking people, but generally they're educated - either very concerned about politics or the environment, or both," she says.
Somewhat worn old Mercedes cars seem to be the most popular vehicles among the biodiesel set.
Diesel has never been very popular with American drivers, meaning most suitable cars are imported - mostly Mercedes and Volkswagens.
Many are strongly opposed to the war in Iraq and want to sever any link with a conflict they believe is motivated by desire for oil, and with a government they say is closely tied to the oil industry.
Ms Zimmermann says biodiesel is only likely to be taken up seriously when it is as cheap as regular fuel - "When people realise 'wow, I can run my truck on waste oil from Burger King'."
COOL SCHOOLS, SONOMA COUNTY
Sonoma County in northern California has taken it upon itself to reduce its carbon emissions 25% below its 1990 level by 2015 - one of the toughest targets in the US.
While the federal government has refused to impose nationwide targets, local communities are taking action themselves.
Nicole (left) and Christine are proud to be pushing for change
Sonoma's Climate Protection Campaign (CPC) is aware that to reach its objective, the county has to act on every level - not least in schools.
"It's young people that have to take on the burden of this issue," says Jessica Kellett, co-ordinator of the CPC's Cool Schools programme.
"We need to have young people to be leaders today - not just to be educated but to understand how to start engaging with elected officials, with their parents, because we need to be taking action now."
Analy High School challenged students to reduce their emissions, primarily by changing the way they got to school.
By promoting walking, biking and car-pooling, they reduced single-passenger car journeys by 21%.
"When you're at school you get your licence, so you want to hop in the car and drive everywhere," says 17-year-old Christine Byrne, who does her best to resist the temptation and cycle whenever possible.
"Through the educational programmes that we've begun, like Cool Schools, people are becoming more aware. It's slowly beginning to grab more people."
Nicole Caughell, 18, helped implement a similar programme at Windsor High School.
"It's pretty cool, it seems really revolutionary - we're the ones spearheading this issue, while still in high school," she says.
"There's a lot of people out there who are listening to us and trying to make a change because of what we're doing. We're really being the example."