( CNN ) -- Recent ballistic missile tests by India , Pakistan and North Korea -- which has ominously threatened to `` reduce to ashes '' the South Korean military `` in minutes '' -- are once again focusing the world 's attention on the dangers of nuclear war . This concern was dramatically underscored in a new report released at the Nobel Peace Laureates Summit in Chicago . Titled `` Nuclear Famine : A Billion People at Risk '' ( PDF ) , the study shows that even a limited nuclear war , involving less than half of 1 % of the world 's nuclear arsenals , would cause climate disruption that could set off a global famine . The study , prepared by International Physicians for the Prevention of Nuclear War and its U.S. affiliate , Physicians for Social Responsibility , used a scenario of 100 Hiroshima-sized bombs exploded in a war between India and Pakistan . If there were such a war , the study estimated that 1 billion people , one-sixth of the human race , could starve over the following decade . Along with recent events , these findings require a fundamental change in our thinking about nuclear weapons . The study , in positing a war between India and Pakistan , shows the importance of understanding that smaller nuclear powers , not just the United States and Russia , pose a threat to the whole world . But the greater lesson concerns the forces of the larger nuclear powers . Each U.S. Trident submarine can destroy 100 cities and produce the global famine described in the study . The United States has 14 of them , a fleet of land-based nuclear missiles , and an arsenal of nuclear weapons that can be delivered by bombers . The Russians possess the same grotesque overkill capacity . Even the most ambitious arms reductions under discussion would leave the United States and Russia with 300 warheads each , most of them 10 to 30 times larger than a Hiroshima sized bomb . This would be a massive arsenal capable of producing the global famine scenario many , many times over . These arsenals are an archaic , but lethal , holdover from the Cold War . Their continued existence poses an ongoing threat to all humanity . Steps can and should be taken immediately to lessen this danger . Substantial numbers of these weapons remain on what The New York Times has described as `` hair-trigger alert . '' They can be fired in 15 minutes or less and destroy cities a continent away 30 minutes later . This alert posture creates the needless danger of an accidental or unintended launch , and the United States and Russia have had many close calls , preparing to launch a nuclear strike at the other under the mistaken belief they were under attack . The most recent of these near-misses that we know about took place in January 1995 , well after the end of the Cold War . The United States and Russia should stand down their nuclear arsenals so that it takes longer to launch their missiles , lessening the danger of an accidental war . U.S. President Barack Obama and Russian President Vladamir Putin can take this step on their own without negotiating a formal treaty . Beyond this , it is time to begin urgent talks aimed at reducing the U.S. and Russian arsenals as the next essential step toward multilateral negotiations for a Nuclear Weapons Convention , a binding , verifiable , enforceable treaty that eliminates nuclear weapons altogether . As former Soviet President Mikhail Gorbachev observed on reviewing the new `` Nuclear Famine '' study : `` I am convinced that nuclear weapons must be abolished . Their use in a military conflict is unthinkable ; using them to achieve political objectives is immoral . `` Over 25 years ago , President Ronald Reagan and I ended our summit meeting in Geneva with a joint statement that 'Nuclear war can not be won and must never be fought , ' and this new study underscores in stunning and disturbing detail why this is the case . '' The opinions expressed in this commentary are solely those of the writers .
Writers : India , Pakistan and North Korea missile tests bring up dangers of nuclear war . Study shows war using half of 1 % of global nuke arsenals would set off world famine . U.S. and Russia have huge nuclear arsenals , they say , a lethal holdover from Cold War . Comment: