http://news.bbc.co.uk/1/hi/world/americas/6288172.stm
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.
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. 
Sebastopol mayor
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 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.
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'."
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. 
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.
Student
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."http://news.bbc.co.uk/1/hi/world/americas/6896365.stm
| By Sam Wilson BBC News, Napa Valley |
Creating wine is all about getting the balance right.
You have to find the best location, with good soil, the right range of temperature, and rain at certain times of year. You must plant the right grapes.
And then you must get lucky with the weather.
So it is no wonder that winemakers are especially aware of the issue of climate change.
Some studies have suggested that the wine map could be changed completely if global warming proceeds apace over the coming decades.
In North America's most renowned wine-growing region, Napa Valley in California, current conditions are near-perfect.
"You have the climate, you have ideal soils and a history of winemaking that goes back to the turn of last century. It's a combination of those things that makes Napa Valley unique," says Jeff Virnig, winemaker at Robert Sinskey Vineyards.
A subtle variation of temperatures and conditions in different places means "you can pretty much grow any grape variety here in this valley".
Alarmed
Some scientists say global warming could turn that all on its head.
A study by the America's National Academy of Sciences last year suggested that the area of the US suitable for growing premium wine grapes could decline by 81% by the end of the century.
Findings like that have alarmed wine industry figures around the world.
Pancho Campo, a Spaniard who put on the first international Global Warming and Wine conference last year, urged attendees to "spread the word... It might not help sell wine today, but global warming will bite us all in 20 years' time".
Napa Valley Vintners
He had particular reason for concern, as studies suggest Spain would be one of the first wine-growing areas to become unviable.
The effects on cooler regions, however, might be beneficial, at least initially.
In Bordeaux, for instance, recent vintages have been acclaimed, following a succession of warm summers that have allowed it to ripen its grapes more consistently than before.
The US study suggested that climate change could make viticulture much more successful in northern parts of Europe, at the expense of Spain, Italy and the south of France.
'No crisis'
At Napa's Sinskey Vineyards, they believe the worst-case scenarios are alarmist.
"The sensational aspects that you hear - that's doom and gloom," says owner Robert Sinskey.
As a farmer who has seen many unexpected weather events in his time, he is reluctant to say definitively that the climate is in flux. 
"What we can say is we have an impression that change is happening. Are we in crisis mode? No we're not."
In any case, Napa Valley growers believe their proximity to the Pacific coast may protect them from the worst effects of climate change.
"As the interior of California heats up, coastal regions actually cool off," says Terry Hall, a spokesman for Napa Valley Vintners.
This is because hot air inland rises, drawing in cool, moist air from over the sea.
"2005 was the warmest year ever in the US," he says. "For us [in Napa], it was a very cool year.
Vineyard owner
"The headlines read that Napa's going to hell in a handbag," he says. In fact, he says, "microclimate cooling may be as big an issue for us as global warming."
Napa's refusal to panic over climate change does not mean it is unconcerned, however.
Mr Hall says it is vital not just to accept that climate change is under way, but to "make that a cornerstone of your agricultural decisions".
That might mean planting different varieties, or thinning fewer leaves from the vines to provide more shade.
In Sinskey's case, it means trying to make practices as environmentally friendly as possible.
Organic buffer
Walking round the vineyard, winemaker Jeff Virnig shows how he allows grass and plants to grow between the vines, to recycle organic material into the soil. The grass is grazed by sheep.
"One of the reasons we've gone to organic farming practices is we figured we'd be better able to buffer against extremes of weather," says Mr Virnig.
By raising the level of organic material in the soil, he explains, it can hold more water, which is useful both in dry and wet periods.
The winery is also decked with solar panels, that produce 75% of the power needed on the site. Its trucks and tractors run on biodiesel.
Robert Sinskey believes that as someone who makes a living off the land, he has a responsibility to work in "the most efficient, least intrusive way possible". 
He says that also makes good business sense.
"Our customer base are highly educated. If they're not practising green, they're thinking about it. If we can inspire in any way and also be true to the spirit, and non-damaging, there's a security in doing business that way."
And if the worst-case scenarios come to pass, getting the right acidity and crispness in his pinot noir will be the least of his problems.
"If we were to see dramatic change, we'd have to kiss our business goodbye," he says.
"But I think there'd be bigger concerns than our business. We'd be concerned about basic survival."http://news.bbc.co.uk/1/hi/in_depth/629/629/6528979.stm
Some regions are likely to experience water shortages. Coupled with increasing demand, this is likely to result in large increases in the number of people at risk of water scarcity. It is likely to affect livelihoods, the report by the International Panel on Climate Change says. 
Projected reductions in the area suitable for growing crops, and in the length of the growing season, are likely to produce an increased risk of hunger. In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020.
Rising sea levels threaten large cities. Degradation of coral reefs and mangroves is likely, with impacts on local fisheries and tourism.
Rising temperatures, coupled with over-fishing, will decrease the supply of fish from large lakes, with important impacts on food supplies.
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Glacier melting in the Himalayas is virtually certain to disrupt water supplies within the next 20 to 30 years. Floods and rock avalanches are virtually certain to increase. Heavily-populated coastal regions, including the deltas of rivers such as the Ganges and Mekong, are likely to be at risk of increased flooding. 
Economic development is likely to be impacted by the combination of climatic change, urbanisation, and rapid economic and population growth.
Forecast changes in temperature and rainfall are likely to reduce crop yields overall, increasing the risk of hunger.
The presence of lethal diarrhoeal diseases associated with floods and droughts is expected to rise in East, South and Southeast Asia and rises in coastal water temperature could exacerbate cholera in South Asia.
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Ongoing water shortages, notably in southern and eastern Australia, are likely to get worse by 2030. 
Ecologically important regions such as the Great Barrier Reef and Kakadu National Park are likely to lose a significant part of their wildlife before then, by 2020.
Some coastal communities are very likely to see an increased risk of coastal storms and flooding.
Temperature rises of 1C-2C are likely to bring benefits to cooler areas, such as New Zealand, in the form of longer growing seasons and reduced energy demand. Greater warming is likely to bring a net negative impact - such as increased risk of drought and fire.
Nearly all European regions are expected to be negatively affected by some future impacts of climate change.
Central and Eastern European countries could face less summer rainfall, causing higher water stress. Health risks due to heat waves are expected to increase. Forest productivity is expected to fall and the frequency of peatland fires to increase.
Southern European countries are very likely to see reduced water supplies, lower crop production, more wildfires and health impacts from increased heatwaves.
Northern countries are likely to benefit from increased crop yields, forest productivity, and food supplies from the North Atlantic. By 2020, most areas of Europe are likely to see an increased flood risk.
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Increasing temperatures and decreases in soil water in the eastern Amazon region would lead to replacement of tropical forest by savannah. Species extinctions are likely. 
Drier areas are likely to see salinisation and desertification of agricultural land, with falling crop yields and livestock productivity reducing food security. However, soybean yields are likely to increase in temperate zones.
Sea level rise is very likely to bring flooding to low-lying regions such as the coast of El Salvador, Guyana and the Rio de la Plata estuary. Increasing sea temperatures are likely to impact coral reefs and south-east Pacific fish stocks.
Changes in rainfall patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation.
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Warming in western mountains is very likely to reduce snowpack, bringing more floods in winter and reduced water supplies in summer. 
Increases in problems with pests, diseases and forest fires are likely.
Cities with a history of heat waves are likely to experience many more, with potential health impacts, especially for the elderly.
Rising sea levels, severe weather and storm surges, combined with population growth in coastal areas, are very likely to increase economic losses.
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Reductions are likely in the thickness and extent of glaciers and ice sheets, and the extent of sea ice and permafrost. 
The depth of summer permafrost melting is likely to increase.
Changes to natural ecosystems are likely to impact migrating birds, mammals and higher predators adversely. Specific ecosystems and habitats are expected to be vulnerable, as climatic barriers to species invasions are lowered.
There are virtually certain to be both negative and positive effects on Arctic peoples. Detrimental impacts would include those on infrastructure and traditional indigenous ways of life while beneficial effects would include reduced heating costs and more navigable northern sea routes.
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Sea level rise is likely to worsen floods, storm surges and coastal erosion, with impacts on the socio-economic wellbeing of island communities. 
Beach erosion and coral bleaching are likely to reduce tourism.
There is strong evidence that water resources in small islands are likely to be seriously compromised.
Increased invasion by non-native species is likely.
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The supply of water is very likely to increase at higher latitudes and in some wet tropics, including populous areas in east and southeast Asia. It is very likely to decrease over much of the mid-latitudes and dry tropics, which are presently water-stressed areas. 
Drought-affected areas will likely increase. Instances of extreme rainfall are likely to increase in frequency and intensity, raising the risk of floods. Increases in the frequency and severity of floods and droughts will have implications on sustainable development.
Water volumes stored in glaciers and snow cover are very likely to decline, reducing summer and autumn flows in regions where more than one sixth of the world population currently live.
Many ecosystems are likely to be challenged beyond their capacity to adapt over the course of the century by an unprecedented combination of climate change, associated disturbances such as wildfires, and other aspects of modern-day global change. 
In the second half of this century, ecosystems on land are likely to become a net source of carbon rather than a net absorber. This extra carbon will amplify climate change.
Roughly 20-30% of species are likely to be at high risk of irreversible extinction if the global average temperature rises by 1.5-2.5C beyond 1990 levels. For increases in global average temperature exceeding 1.5-2.5C, there are very likely to be major changes in ecosystems which will adversely effect the environmental goods and services which humans use.
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Crop yields are likely to increase at higher latitudes for global average temperature increases of up to 1-3C (depending on the crop), and then decrease beyond that. This is even after allowing for effects of CO2 fertilisation. 
At lower latitudes, especially the seasonally dry tropics, crop yield potential is likely to decrease for even small global temperature increases, which would increase risk of hunger.
Global agricultural production potential is likely to increase with increases in global average temperature up to about 3C, but above this it is very likely to decrease.
Increased frequency of droughts and floods would affect local production negatively, especially in subsistence sectors at low latitudes.
Coasts are very likely to be exposed to increasing risks due to climate change and sea level rise, and the effect will be exacerbated by increasing human-induced pressures on coastal areas. 
It is likely that corals will experience a major decline due to increased bleaching and mortality due to rising seawater temperatures. Salt marshes and mangroves will also be negatively affected by sea-level rise.
Many millions more people are expected to be flooded every year due to sea-level rise by the 2080s, especially in densely populated and low-lying settlements which already face other challenges such as tropical storms or local coastal subsidence. The numbers affected will be largest in the mega-deltas of Asia, but small islands face the highest relative increase in risk.
The benefits and costs of climate change for industry, settlement, and society will vary widely by location and scale. Some of the effects in temperate and polar regions will be positive, and others elsewhere will be negative. Generally, a higher degree of warming is more likely to bring negative consequences. 
The most vulnerable industries, settlements and societies are those in coastal and river flood plains, those whose economies are closely linked with climate-sensitive resources, and those in areas prone to extreme weather events, especially where rapid urbanisation is occurring.
Poor communities can be especially vulnerable because they tend to be concentrated in relatively high-risk areas, have more limited coping capacities, and can be more dependent on climate-sensitive resources such as local water and food supplies. Where extreme weather events become more intense, the economic costs of those events will increase, and these increases are likely to be substantial in the areas most directly affected.
Projected climate change is likely to affect millions of people, particularly those with low capacity to adapt, through increases in malnutrition and consequent disorders. 
This will have implications for child growth and development; increased deaths, disease and injury due to heat waves, floods, storms, fires and droughts, the altered burden of water-related diseases; the increased frequency of cardio-respiratory diseases due to higher concentrations of ground level ozone, and the movement of some infectious disease carriers into new regions. vectors.
Climate change is likely to have some mixed effects, such as the expansion and contraction of the range of malaria in different regions. In some places, climate change is likely to bring some benefits to health such as fewer deaths from cold exposure.
IPCC definitions of probability of occurrence
Virtually certain: more than 99%Extremely likely: more than 95%
Very likely: more than 90%
Likely: more than 66%
More likely than not: more than 50%
Very unlikely: less than 10%
Extremely unlikely: less than 5%
