Just as Al Gore's global warming documentary, "An Inconvenient Truth," sought to raise public awareness about climate change, the sobering film "Countdown to Zero" makes a compelling case for nuclear disarmament by depicting a world dangerously poised for possible disaster.

It could be the rash decision of a rogue state, an individual act of terrorism, or a simple accident, but British director Lucy Walker says the chances of nuclear destruction are greater now than ever in an increasingly volatile world.

"We're snoozing on the nuclear threat for sure," Walker says by phone from New York in a recent interview.

"I think the technology is getting far easier to achieve, that's one problem, and I think post-9-11 terrorism is much more sophisticated, that's another problem."

Bolstering her view are insights from an impressive list of world leaders and experts, including former U.S. president Jimmy Carter, former Soviet leader Mikhail Gorbachev, former Pakistan president Pervez Musharraf, former U.K. prime minister Tony Blair, as well as former CIA experts, physicists and writers. Even a Russian smuggler, who was caught selling weapons-grade bomb material to a man he believed belonged to al-Qaida, appears in the documentary.

The film traces the history of the atomic bomb from its origins to black-market proliferation today. Currently, nine nations possess nuclear-weapon capabilities and others are racing to join them.

"Even just one nuclear disaster is so cataclysmic that it's just game changing," says Walker, who is nevertheless encouraged by a current resurgence in the disarmament movement led by U.S. President Barack Obama.

"There have been reductions, but any sort of algebra of, 'You can destroy the planet X times over' is bad algebra, if you ask me.... And as time goes on, the risk isn't zero - there's a sort of statistical likelihood occurring that something (will happen). It's just a matter of when, not if."

While the overall number of weapons has dropped since the Cold War, Walker points to the staggering number still in existence.

"The Cold War ended and there was this nice assumption that weapons would be put away now... that somehow the weapons aren't still there, pointed, ready to be launched within one minute," says Walker.

"And they're still there pointing. It's a brazen example of institutional inertia. No matter how bad U.S.-Russian relations may seem, on any given day this week, it's not like we need to be launching missiles at every one of their cities within one minute."

Walker's previous films include "Blindsight," about six Tibetan blind teens who climb Mt. Everest, and "Wasteland," about Brazilian artist Vik Muniz and a group of garbage pickers that work in a massive dump in Rio.