In the 1980s, there was a general understanding that a large-scale nuclear war between the U.S. and the Soviet Union would be a disaster for the whole world. Recent research has shown that even a limited nuclear war, as might happen between India and Pakistan, would also cause a global catastrophe.

The new research has fueled a growing international movement to abolish nuclear weapons. Unfortunately, this research is not widely known in the U.S., and most people here continue to act as though the danger of nuclear war ended when the Berlin Wall came down.

So let’s look at the danger we still face, particularly in view of the new data. There remain in the world today more than 17,000 nuclear warheads, the vast majority in the arsenals of the U.S. and Russia. While the danger of a deliberate war has decreased since the end of the Cold War, both countries continue to spend tens of billions of dollars a year on these weapons, and military doctrine in both countries continues to countenance their use under a variety of circumstances.

Even if the weapons are not used deliberately, there remains the danger of an accidental war. More than 3,000 warheads are maintained on hair-trigger alert, mounted on missiles that can be launched in less than 15 minutes. If used, these weapons would produce a decade-long nuclear winter, with temperatures around the world dropping an average of 15 degrees F. Agriculture and food production would stop, and the majority of the human race would starve. We know of at least five occasions since 1979 when either Washington or Moscow prepared to launch a nuclear war in the mistaken belief that it was itself under attack.

It is not just a large war between the U.S. and Russia that we need to worry about. A report released last year by Physicians for Social Responsibility reviewed studies showing that a war between India and Pakistan involving only 100 Hiroshima-sized bombs—less than half their nuclear arsenals, and less than 0.5 percent of the world’s nuclear weaponry—would also cause global climate disruption. The impact would not be as severe as with a large-scale war, but it would cut world food production enough to cause a global famine.

Data generated just this summer suggests that the food shortfalls would be much more severe than estimated last year. China in particular would face food shortfalls that could put 1.3 billion people at risk and threaten a decade of social and economic chaos in the largest country in the world, a country with a heavy nuclear arsenal of its own.

In response to this new information, a movement has emerged around the world calling for the abolition of nuclear weapons. One hundred and twenty-five countries recently signed a statement at the U.N. calling for a new treaty to ban them. More than 100 nations will meet in Mexico in February to discuss this threat to human survival; a followup meeting is expected later in the year, with negotiations for a treaty to declare the use or possession of nuclear weapons illegal.

So far the U.S., despite President Obama’s talk about a world free of the threat of nuclear weapons, has actively opposed these initiatives. The American people need to demand that the Obama administration live up to its rhetoric and support the growing international movement to abolish nuclear weapons.•

Ira Helfand, M.D. is co-president of International Physicians for the Prevention of Nuclear War.