Think of Arnold Schwarzenegger, and he hardly comes across as a poster-child for the environmental movement. For much of his movie career, he wasn't engaged in saving the planet so much as causing sizeable chunks of it to blow up. Off camera, he cut a figure almost as extravagant as his muscular physique - flying on private jets, showing up at wantonly lavish Hollywood parties, smoking cigars and single-handedly championing production of the Hummer, a civilian version of the ultra-wide four-wheel-drive military Humvee, which is widely regarded as the most obnoxiously wasteful vehicle on America's roads.
And yet the action star turned California governor is nothing if not a man of surprises. He mixes in the social circles of Hollywood's liberal elite and is married to a member of the Kennedy clan, Maria Shriver, and yet he has always regarded himself as a staunch Republican - among other things, an act of rebellion against the staunch social democratic values of his native Austria.
He is capable of schmoozing with the hardest of hard-edged conservatives from the Bush administration, and yet he shares none of their puritanical disgust for gay marriage, abortion rights or any of the other social "wedge issues" that have proved so successful in promoting Republican candidates and securing party control of both houses of Congress as well as the White House.
When Schwarzenegger made his typically dramatic entry into politics three years ago - throwing himself behind a rebellion against California's anaemic then-governor Gray Davis and replacing him in a special recall election - he promised to break all the usual rules of the game and use his celebrity to shake up a broken system. Until now he has proved something of a disappointment on that front, falling in with much the same special-interest campaign contributors he had denounced so loudly on the stump.
This week, though, marks something of a watershed. After months of negotiation with the Democratic leadership in California's state assembly, he gave his blessing to a ground-breaking initiative on global warming - a new state law that would require California businesses to cut greenhouse gas emissions by 25 per cent before 2020.
It's hard to overstate the significance of this, especially at a time when the Republicans in Congress and the Bush administration have treated the whole question of global warming as the fever dream of a bunch of ivory-tower scientists and academics they feel they can safely ignore. Schwarzenegger's fellow California Republicans are furious, as is the state Chamber of Commerce, which until now felt convinced it had the governor in its pocket.
There are plentiful reasons to see Schwarzenegger's move as smart politics, though. First of all, environmental activism is popular with California voters - eight out of 10 told a polling organisation last month they regarded global warming as a threat to the economy as well as their quality of life. As Schwarzenegger runs for re-election this November, he can now be confident he has robbed his Democratic challenger, Phil Angelides, of any possibility of attacking him for his environmental policies.
The initiative is also an opportunity to put California - powerful enough to qualify as the world's sixth largest economy - in the forefront of an issue that will have to be addressed, sooner or later, by everyone. Just a month ago, Schwarzenegger scored a major coup when he persuaded Tony Blair to share the limelight with him, instead of the recalcitrant Bush administration. Together, they announced a joint UK-California partnership on combating climate change.
Both men share a similar conviction - that the only way to reverse global warming is to find market-oriented solutions and convince companies it is in their economic interest to cut emissions. Under the deal hashed out this week, California will introduce a trading system so that companies ahead of schedule on cutting greenhouse gas emissions can sell the excess as a form of credit to companies running behind. In other words, environmental virtue will carry a monetary value.
He is breaking the Republican Party mould on other issues as well. He has approved funding for stem-cell research that the Bush administration, influenced by its Christian fundamentalist grass roots, feels is unethical. And he has championed an increase in the minimum wage and helped to devise a discounted drug scheme for the uninsured.
In some ways, Schwarzenegger is now governing like a Democrat - an acknowledgement that California remains a solidly Democratic state. Perhaps more significantly, he is spurning the wishes of his corporate campaign contributors, from whom he has assiduously extracted tens of millions of dollars, and stretching the patience of his party's grass-roots supporters.
The gamble, bolstered by Schwarzenegger's considerable personal charisma and continuing movie-star status, is certainly paying off. His popularity ratings, which were mired somewhere in the mid-30s this time last year, have climbed back up over the 50 per cent mark, and his prospects for re-election look distinctly rosy.
This is the Schwarzenegger that Californians thought they were voting for three years ago but has taken a long time in coming. He may have been in elective politics for only three years but already he has undergone several dizzying transformations, to the point where it is hard to remember that there has been just one man, not three, in the governor's office since November 2003.
The first incarnation of Arnold the Politician, which lasted until the end of 2004, was of the slick, somewhat superficial campaigner who filled his speeches with body-building metaphors and well-known lines from his Terminator movies, but didn't betray too many hints of what he actually intended to do in office. Everything, in this phase, was "fantastic". He opened a smoking tent outside the state capital building in Sacramento so he could share his cigars with legislators, slapped a lot of backs and, memorably, used his charisma to give George Bush some crucial last-minute presidential election campaign support in Ohio, where he just happened to be attending an annual body-building contest.
The biggest challenge in that first phase was a multibillion-dollar budget deficit, which Schwarzenegger vowed to sort out once and for all. But all his vague campaign lines - to cut down on waste and eliminate spending mandates established on behalf of special lobbying interests - proved easier to say than to enact. One person's waste, after all, is another person's pay packet. So Schwarzenegger, together with the legislature, put together an underwhelming bond measure to cover the immediate budget shortfall but shrank away from making tougher decisions.
The second incarnation, which first manifested itself in 2004 but mostly spanned the 2005 calendar year, was altogether harder edged. Having initially made friends with the Democrats in the state assembly, he now denounced them as "girlie-men" and vowed to use his celebrity status to shove a hard-line Republican agenda down their throats. When they refused to go along with him, he decided to go straight to the people.
Sure enough, Schwarzenegger called a special election last November, inviting Californians to clobber the political reach of the (overwhelmingly Democrat) public service unions, gut a key provision of education funding, and give him unprecedented powers to change the budget without legislative approval if revenues started to falter.
The whole initiative was a disaster. Schwarzenegger's attacks on public service workers - he once told the state's nurses he would "kick their butts" - backfired spectacularly. A brief flirtation with the vigilante movement calling for mass expulsion of Mexican immigrants lost him the sympathy of the state's growing Latino population. His popularity plummeted, and the quartet of ballot measures he championed last November all went down to defeat.
Clearly, a new incarnation was called for. So Schwarzenegger stopped listening to his hard-line Republican advisers and paid closer attention instead to his wife, who had disapproved of the special election from the get-go. He hired a prominent Democrat - and, to the horror of the social conservatives, a lesbian - as his new chief of staff, and revamped his media strategy to make himself more available, more spontaneous, and more open to public criticism.
"I've tested movies, and I know right away," Schwarzenegger told reporters as he explained the changes. "I've got to re-edit this thing."
Soon, he and the assembly Democrats were best friends again, making plans for an ambitious public works scheme to overhaul California's groaning infrastructure of roads, bridges, aqueducts and river dams. This year's budget was, unusually, done and dusted on time, without the slightest hint of partisan rancour.
Part of that can be ascribed to luck. The California economy, whose temporary woes earlier in the decade had prompted the budgetary shortfall, has started recovering, which means that the state's coffers are filling up again and that the immediate need for either tax increases or draconian cuts in public services is gone.
Part of that, though, is a testament to Schwarzenegger's dogged refusal to bow to political convention. The environment, curiously, is one area where he has been relatively consistent all along - harking back to the environmentalism of Republicans such as Teddy Roosevelt and Richard Nixon rather than following the Big Oil agenda of the Bush administration and much of the rest of the modern Republican movement.
With some of his wife Maria's best friends as his advisers, he has promoted solar energy and other renewables, hydrogen fuel cell technology and cleaner car exhaust pipes. These initiatives have not been spectacular, but they have been several shades more progressive than those of his Democratic predecessor, Governor Davis.
Now, perhaps improbably, he is making a serious claim to be regarded as the ultimate Green Governor. If his gamble pays off - if the state holds its nerve and California enjoys a new boom in technologies to combat global warming - he will have earned himself more than a political legacy. The whole planet may have cause to be grateful to a muscle-bound movie star.
A Life in Brief
BORN Arnold Alois Schwarzenegger, 30 July 1947, in Thal, Austria, to police chief Gustav Schwarzenegger and his wife Aurelia.
EDUCATION Attended local schools, and as a teenager began attending a gym in nearby Graz for weight training and body building. BA in international marketing and business administration (1979) from the University of Wisconsin-Superior.
FAMILY Married to TV journalist Maria Shriver, 1988; four children.
CAREER Body-building: Junior Mr Europe, 1965, followed by four Mr Universe and seven Mr Olympia titles. (Documentary about his career: Pumping Iron, 1977.) Acting: Best known for his action films, particularly the Terminator series (1981-2003. Politics: Governor of California (2003 - ).
HE SAYS "I would rather be Governor of California than own Austria."
THEY SAY "Governator III is a different person than Governator II. He's being much more the Kindergarten Cop than the Terminator." - Phil Trounstine, political media consultant