US spends 7 billion a month on Afghanistan

Al Qaeda nuclear terror threat high

“Countdown to Zero’’ includes the troubling and well-known development of Iran’s nuclear program, but its writer and director, Lucy Walker, also chronicles little-publicized thefts of enriched uranium that show this fear has been more reality than rumor.

As Mowatt-Larssen says in the film: “There are three ways to acquire a nuclear weapon: You can steal a bomb. You can buy a bomb. And you can build a bomb.’’ Walker shows that all three options are very much in play.

According to Dr. Ira Helfand of Northampton, former president of Physicians for Social Responsibility, even a relatively small nuclear exchange between, for example, India and Pakistan would have serious global repercussions. Temperatures across the planet would drop about 1.3 degrees centigrade, Helfand said, and lead to mass starvation.

In a large-scale nuclear war, temperatures would drop 8 to 10 degrees centigrade, agriculture would be devastated, and “the likelihood is that the entire human race would starve to death,’’ Helfand said during a panel discussion after a recent screening at the Coolidge Corner Theatre in Brookline.

“Countdown to Zero,’’ developed by Participant Media in conjunction with the World Security Institute and Magnolia Pictures, has been shown at the Cannes and Sundance film festivals. However, the sparse turnout at the Brookline screening underscored the difficulties that the documentary faces in attracting a large, paying audience.

“We have kind of an issue fatigue that all of us understandably experience,’’ said the Rev. Jim Antal, president of the Massachusetts Conference of the United Church of Christ, who also spoke after the screening. To help counter that fatigue, Antal plans to send an alert to all of the 400 churches and clergy in his jurisdiction.

“This problem has not gone away,’’ Antal said.

The issue of complacency or unawareness might be even more acute among younger people who have no recollection of the Cold War and its hair-trigger threat of nuclear annihilation.

Ryan Scott McDonnell, executive director of the Boston Faith & Justice Network, said the group will be encouraging its 5,000 young men and women to watch the film.

“This is a first step to convince people that this is an issue that you at least need to learn about even before you care about it,’’ McDonnell said. “But that’s just the starting point.’’

Despite the seemingly increasing nuclear threat posed by terrorists and rogue organizations, some activists see more opportunities for large-scale disarmament. The United States and Russia already have dramatically reduced their nuclear arsenals, and Presidents Obama and Dmitry Medvedev have pledged to eliminate even more weapons.

The Nobel Peace Prize committee made Obama its 2009 recipient partly because of his support for universal nuclear disarmament. And that effort, by the leader of one of the world’s two nuclear giants, is an important reason for hope, Antal said.

“This is an unprecedented opportunity for humanity to put the genie back in the bottle,’’ Antal said. “To have a person of Obama’s values in his position, and his relations with the Russians, I just think this is something that can give the world hope.’’

Time, however, might be running short.

Allison said that while the threat of all-out nuclear war has declined, the rise of terrorism continues to make the intersection of motive and materials a wildly unpredictable one.

Indeed, Allison said in a phone interview, the findings of a congressionally appointed committee on weapons of mass destruction and terrorism underscored the dangers. Allison, who was a member of that committee, recounted its conclusions from 2008.

“We said that, unless there’s some significant change from the current trend lines, we believed it was more likely than not that there would be a successful nuclear or biological attack somewhere in the world before the end of 2013,’’ Allison said.

“I subscribe to that.’’