Updated

The scene: a Manhattan art-house theater. The cause: a campaign against the gas drilling process known as fracking that's being led by more than 100 celebrities, including Yoko Ono, Sean Lennon, Robert Redford, Mark Ruffalo and Mario Batali.

Outside, demonstrators in hazmat suits circle the theater. Inside, actress Scarlett Johansson attends a benefit screening of "Gasland," the documentary film that has become the movement's manifesto. Johansson tells The Associated Press that her "Avengers" co-star Ruffalo introduced her to the cause, and that she found the film "incredibly shocking."

The campaign has galvanized hundreds of thousands of followers, but as with many activist causes, the facts can get drowned out by the glitz. Now, some experts are asking whether the celebrities are enlightened advocates or NIMBYs — crying "Not in my backyard!" — even as their privileged lives remain entwined, however ruefully, with fossil fuels.

Much of the anti-fracking activism is centered in New York City, where concerts, movies and plays use huge amounts of energy, gourmet chefs including Batali cook with gas, and most people — the glitterati included — heat with gas.

There's no doubt that critics of hydraulic fracturing — a practice colloquially known as fracking that involves injecting water, sand and chemicals into underground rock to free vast reserves of gas — have some legitimate concerns. There have been documented cases of leaking gas ruining nearby well water, of air pollution and of problems from the waste the drilling generates. Experts say those are important parts of the story — but far from the whole story.

More On This...

"With proper regulation and enforcement, gas provides a very substantial health benefit in reducing air pollution," compared with coal-fired power plants, said Daniel Schrag, director of Harvard University's Center for the Environment.

That is a theme not adequately covered in the debate over fracking, agreed Michael Greenstone, an environmental economics professor at the Massachusetts Institute of Technology and a former top adviser to the Obama administration. Greenstone is studying the local health effects of fracking, but he said it's not scientifically accurate to ignore "the tremendous health gains" from the coal-to-gas shift.

"Honestly," he said, "the environmentalists need to hear it."

The main celebrity anti-fracking campaign took off last summer when Ono and Lennon, her son, founded Artists Against Fracking. Their family farm sits near gas reserves in New York, and they fear fracking might be allowed in the area. Some celebrities also speak out independently, or through other groups. Among the claims:

— Ono, at a news conference: "Fracking kills. And it doesn't just kill us, it kills the land, nature and eventually the whole world."

— Robert Redford, in a radio ad: "Fracking is a bad deal for local communities. It's been linked to drinking water contamination all across the country. It threatens the clean air we breathe."

— Alec Baldwin, in an editorial in the Huffington Post, described a scenario in which companies promise people "some economic benefit, deliver a pittance in actual compensation, desecrate their environment and then split and leave them the bill."

— Josh Fox, the director of "Gasland," to the AP: "We have the capability of running everything in this country — including our fleet of 240 million cars — off of electricity from wind and from solar and from hydropower." Fox said that society should be changing over "to renewable energy and doing it vigorously and quickly. And we could be doing that in New York."

While such claims may contain a kernel of truth, they are at best subjective and at worst misleading or even hypocritical, some environmentalists say.

"In truth, celebrities are rich, and they use far more energy and resources than anyone else. There's this grass-roots NIMBY revolt against fracking," said Michael Shellenberger, who heads the Breakthrough Institute, a nonpartisan Oakland-based environmental think tank that is releasing a report this month on the environmental benefits of natural gas.

Many self-labeled "fractivists" say drilling ruins drinking water and farms — think the fictional disaster spun in the Matt Damon vehicle "Promised Land" — and makes no sense, since it's possible to quickly transform our society to one that's powered by clean, renewable energy such as wind and solar.

Yet the boom has created jobs, reduced imports of oil and gas, and lowered energy bills. In contrast with Baldwin's claim, local landowners have received billions of dollars in royalties, and the typical royalty of 18.75 percent is higher than what many novelists, actors or musicians are paid.

Pennsylvania dairy farmer Shawn Georgetti said he was struggling before signing a gas lease. Now, he's been able to buy better and more fuel-efficient equipment and says the drilling hasn't caused any problems. "It's a lot more fun to farm," he said.

As for Fox's claim about the ease of shifting to wind, solar and hydropower, "if that was true, we'd be doing it," said Stephen Ansolabehere, a Harvard University professor who has studied public attitudes toward renewable energy. "People think wind and solar are cheap; it's just not right. They see what the prices are, and the support drops."

Wind energy currently provides about 2 percent of total U.S. energy, and solar less than 1 percent. Hydropower is about 3 percent, and building more dams would also have environmental effects. In practical terms, it will take decades of nonstop solar, wind and other renewable investment to phase out fossil fuels.

Many celebrities are just beginning to embrace renewables. Sean Lennon told the AP in January that the family farm in upstate New York is still conventionally powered.

"I'm actually looking into it. It's a long process," Lennon said. "I've met with a lot of solar companies. I'm looking for the best possible solution, and there are a lot of options out there."

Redford spokeswoman Joyce Deep wrote in an email that he installed passive solar in his home in the mid-'70s, but she didn't know details about more recent installations. "Passive solar" means using windows or other materials in an energy-conscious way, not solar panels. Deep noted that Sundance, the Utah resort Redford helped found, uses some renewable energy.

Baldwin declined to comment about how much renewable energy he had installed, and Ono's spokesperson said Lennon spoke for her, too.

Ruffalo, an Academy Award-nominated actor, made the switch to solar last year on his property in New York's Catskill Mountains, also near gas reserves. "In fact, I have a 14 KW system on my single property," Ruffalo wrote in an email. "It is a beautiful system." And Fox said he uses electricity from wind power on a Pennsylvania property.

But experts note that even renewables need conventional backup, since the sun doesn't always shine and the wind doesn't always blow.

"It demonstrates the ignorance of renewable power advocates to suggest that renewables can run without gas. We don't get to say, 'I only want solar and wind,'" Shellenberger said.

Even the success that turns people into celebrities often involves tremendous amounts of energy. Restaurateur and Food Network star Batali started with one restaurant. He now has 16 — in New York, Las Vegas, Los Angeles, Hong Kong and Singapore — all using natural gas to cook.

Some of his restaurants "use a percentage of green power to help offset some of our non-renewable energy consumption, and we are looking to do more in the future," Batali spokeswoman Elizabeth Meltz wrote in an email.

Some celebrities acknowledge the complexities.

"Obviously the entire society is addicted to fossil fuels, and the reason that we're fractivists is to try to move toward a renewable economy," Lennon said. "That doesn't mean that any of us have extracted ourselves completely from the society itself, because the entire city's running off of oil and gasoline."