Comedy and climate change don't have a lot in common. But Laurie David's an expert in both.

A TV comedy producer turned global warming activist, David knows that the seemingly disparate goals of making people laugh and saving the planet share an important guiding principle: Timing is everything. Even as she calls for fewer CO2 emissions, and laments General Motors' "pig-headed leadership" on her Huffington Post blog, David wonders whether we can save the planet before we destroy it.

"We have to move towards a more sustainable world. We have to," says David, who produced Al Gore's Oscar-winning "An Inconvenient Truth." "And we will get there — but how long is it going to take us?"

Growing up on Long Island, David had an aversion to litterbugs. But it wasn't until a fateful breakfast with Robert F. Kennedy in the '90s that she fully comprehended our environmental threats. "I'm not a person who could understand what was happening and not do something about it," says David, who was married to "Seinfeld" writer and "Curb Your Enthusiasm" star Larry David until last year. "It wasn't even a choice like, 'I could have lunches every day or I could work on global warming.' It was urgent and necessary and I had to do everything I could."

Towards that end, she founded the Stop Global Warming Virtual March, produced the 2005 comedy special "Earth to America!" with Jack Black and Tom Hanks, and launched last year's Stop Global Warming College Tour with Sheryl Crow. "One of the best ways to impart information is to entertain people while you're doing it," says David, dubbed "the Bono of climate change" by Vanity Fair. "That's been my M.O.: to present stuff in a non-wonky way, to bring everyone into the movement."

Pop culture and peer pressure go a long way toward changing minds — and behaviors, says David, who used to yell at SUV drivers on the highway until her mortified daughters, 12 and 14, begged her to stop. "I will always admire Leonardo DiCaprio for being the first guy to get into a hybrid car and make it sexy," she says. His efforts, and hers, are starting to pay off. "People are finally realizing that we're all environmentalists! If you enjoy snowy winters, or a normal sunny day, or you want clean water and air, you're an environmentalist. All the things we care about are at risk now."

And — if we fail? "It's a real possibility," she says. "But I don't spend time dwelling on that because there are so many solutions! I know a lot of scientists working on this, and they're all optimists.

"We have the resources to (stop global warming)," she says. "And every single individual can be part of the solution. It's so empowering."