Inside a leaf-coloured cover, an alpha list of names from Julia Roberts to Robert Kennedy Jnr, and George Clooney to Bette Midler are sending a message to their President and all those still in eco-denial. "Time to get real, " the magazine tells its 1 million buyers. "Global warming is the problem the biggest problem. It's not a matter of when any longer. It's here. Green is the future the only future."
Hot in pursuit, Elle magazine ("go green with our round-up of the best organic treatments for your body") will unveil its own environmentally friendly issue this week for May with a competing clutch of celebrities, including Cameron Diaz, television star Evangeline Lilly, supermodel Carolyn Murphy, and yes Robert Kennedy Jnr.
Back here the fashionistas are abuzz about David Cameron, who since being elected Tory leader has given the greenies kudos and clout. This week he heads off to study global warming in the high Arctic togged out against the cold by polar explorer Tom Avery.
"Green is the new black," Graydon Carter, Vanity Fair's editor, declares, promising that the magazine relaunched to exploit Ronald Reagan's "greed is good" era will keep up "an increased commitment to reporting on the threat to our precious environment", especially climate change.
Alongside its adverts for Louis Vuitton handbags, Mercedes people-carriers and Dior diamond watches, it reassures its readers that being green " doesn't need to be grim".
"In this special issue, Vanity Fair cuts through the hand-wringing, denial and confusion about climate change with an in-depth look at the challenge ahead, a 30-page portfolio of a passionately, pro-environment new generation. Don't just sit there, turn the page."
The trouble is that this page, and all the others in the issue, is printed on non-recycled paper. "They were scrambling to do it, but it was too short a time frame and they couldn't make it happen," says one insider.
So the "green edition", critics calculate, has used up 2,247 tons of trees. And that's not to mention the production of 4,331,757 pounds of greenhouse gases, 13,413,922 gallons of waste water and 1,744,060 pounds of solid waste.
Elle promises greater virtue. "We are the first fashion magazine to devote an entire issue to the environment and the first to print that entire issue, including the fashion well, on recycled paper," boasts Carol Smith, the group publishing director. "The response from our advertisers has been absolutely inspiring. The Green Issue is a perfect example of the right idea at the right time in the right magazine."
It is Vanity Fair, however, that wins the eco-celebrity clash. Its green-tinted cover shot by legendary snapper Annie Leibowitz features Julia Roberts green-clad and garlanded with leaves, with George Clooney, Robert Kennedy and Al Gore tastefully laid out at her feet.
Thronging the pages are Arnold Schwarzenegger, the Governor of California; actors Edward Norton and Bette Midler; Lord Browne of Madingley, BP's chief executive (shot by Lord Snowdon); and Zac Goldsmith (described with more awe than accuracy as "the eco-aristocrat".)
All pledge their environmental faith, but it is the former vice-president Gore who grabs the most space by penning a long essay on global warming.
It is something of a second coming for him. He originally ran for high office on an environmental platform, but seemed to forget it once elected: America's emissions of greenhouse gases grew so fast under him and Bill Clinton that George Bush could never have met the Kyoto Protocol's targets, even if he had wanted to.
If Al Gore had stuck to his principles first time round he would probably be president today.
For Ralph Nader ran against him on a Green Party platform, capturing enough votes in Florida from disillusioned environmentalists to hand the White House to the "Toxic Texan".
For those who do want to practise what they preach, Vanity Fair includes a pull-out supplement advising its readers to stop using plastic carrier bags, use green household paints, grow grass on their roofs and finish off with green burials in wicker coffins.
Its conversion has bemused eco-Brits. "It's quite ironic that a magazine which champions the most destructive lifestyles are now majoring with green issues," says Tony Juniper, the director of Friends of the Earth.
But even he concedes it may convince the glamour-hungry that being green does not inevitably entail endless lentils and unbleached linen shirts.
Additional reporting: Marie Woolf