The blinding light. The microsecond of silence before the roar. The mushroom cloud. For children of the Cold War, nuclear holocaust remains the ultimate nightmare.

Yet for many, the nuclear threat today seems as antiquated as the dial-up connection Matthew Broderick’s character used to hack into the NORAD system in the 1983 movie War Games. Think again.

The planet is still bristling with nukes—23,000 of them scattered among nine nuclear powers, including some countries rife with instability. Dozens more either have enough nuclear materials to build a bomb or are in hot pursuit of the materials necessary to do so.

It would only take one weapon falling into the wrong hands to unleash unimaginable death and destruction. That scenario is frighteningly possible. As I write this piece, reports from nuclear-armed Pakistan tell of Taliban troops overrunning towns just 60 miles from the capital, Islamabad. It reminds us of just how thin the buffer can be between security and devastation.

If extremists got their hands on a nuclear weapon, it would be too late to do anything about it. Terrorist groups cannot be deterred. And a softball- size amount of plutonium (enough to crush a city) smuggled in an average-looking van would be nearly impossible to detect. Counting on a real-life Jack Bauer to save us is not a strategy.

Here in Los Angeles—where giant explosions are usually saved for moviesets—the issue feels remote. But it is urgent.

Our margin for error is zero. The only long-term solution is to reduce the threat to zero—rid the earth of nuclear weapons.

This is not “Kumbaya” thinking. The former US chief negotiator for the Strategic Arms Reduction Treaty (START) recently presented a feasible plan to get to “global zero.” It starts with the US and Russia—which together have 96 percent of the world’s nukes—demolishing their arsenals, followed by all other nuclear powers phasing to zero. On April 1, President Obama and President Medvedev of Russia met, and in a historic joint declaration, “committed [their] two countries to achieving a nuclear-free world.”

But the ultimate success of denuclearization depends on—you guessed it—us. Politicians act boldly only when they feel the pressure of public opinion. If we’ve learned nothing else from the startling events of the past year, it is that engaged citizens can change everything.

Yes, this is a downer issue. The world won’t be more beautiful on the day we rid it of nukes. The air won’t be sweeter or the grass greener, but a very dark cloud will be lifted.

Through no fault of our own, we were born into a world in which the possibility of nuclear destruction is an omnipresent reality. But through our actions, we can make it so that our children’s children will have one less nightmare to plague their peaceful sleep.