A four-megaton nuclear bomb was one switch away from exploding over the US in 1961, a newly declassified US document confirms.
Two bombs were on board a B-52 plane that went into an uncontrolled spin over North Carolina – both bombs fell and one began the detonation process.
The document was first published in the UK’s Guardian newspaper.
The US government has acknowledged the accident before, but never made public how close the bomb came to detonating.
The document was obtained by journalist Eric Schlosser under the Freedom of Information Act.
How Powerful Are Today’s Nuclear Weapons and, If Used, How Would They Affect the World?
Ask a Scientist – April 2010
K. Carlson from Fort Collins, CO, asks “How much more powerful are today’s nuclear weapons than the ones dropped on Nagasaki and Hiroshima, and if one was actually used, what would the impact be to people and the planet?” and is answered by Senior Scientist & Co-Director of the UCS Global Security Program Lisbeth Gronlund, Ph.D.
The atomic bombs dropped on Hiroshima and Nagasaki were comparable to explosions of about 15 to 20 kilotons of TNT. It is estimated that these two bombs killed roughly 200,000 people in the near term, with more dying in the following years from cancer. In comparison, today’s thermonuclear weapons are much more powerful. An average U.S. weapon would explode with a yield of 300 kilotons of TNT.
The impact of a powerful weapon like this is a little hard to fathom. But here’s what would happen if one of these thermonuclear weapons were actually detonated. First, there would be a large initial blast, creating a destructive shock wave that would collapse most buildings out to three miles, killing most of the people in the area. The blast would be followed by a tremendous amount of heat, which could cause as much, if not more, devastation than the initial blast. In most cities, a big concern would be fires caused by the heat spontaneously igniting fabric and other items within four to five miles of the blast. These fires could coalesce into a firestorm fed by intense winds.
And then there’s the radioactive fallout—large amounts of highly radioactive dust and debris, which could be carried long distances by the wind and could eventually contaminate many thousands of square miles. This fallout would kill thousands of people, cause acute radiation sickness in thousands more, and increase cancer rates for decades across the contaminated area.
There’s also the sheer number of weapons currently in the world today. I remember about 20 years ago, when I was at Cornell, I was looking at the size of the world’s nuclear arsenal and I started looking up U.S. cities by population. Syracuse was about 100 on the list—with the tens of thousands of nuclear bombs that were out there, even a smaller city like Syracuse would easily be a target.
Today there are some 11,000 operational nuclear weapons worldwide. If even a small fraction of these were detonated, there could be global effects. One big concern is the amount of soot and smoke that would be produced from the kind of fires a nuclear bomb can create. A recent study that used climate models to study the effects of a nuclear exchange between India and Pakistan involving 100 weapons found that there would be enough smoke and soot to reduce sunlight and precipitation across the world. There would be shorter growing seasons, which would have an enormous effect on agriculture worldwide. A lot of people would starve. Although these models are difficult to verify, it’s clear that the detonation of just a small fraction of the weapons worldwide would have global effects that last for many decades. Everyone would be affected.
With nuclear weapons, it’s not rational to speak of numbers in terms of how many we purportedly “need” for deterrence; we need to look at arsenal levels based on the reality of the destruction they create. It should be illegal for nations to possess the means of wiping entire countries off the face of the earth in a span of 30 minutes. The limits have to be meaningful, not just political. With the amount of damage these kinds of weapons can cause, the United States has to renew efforts to reduce their numbers and ultimately work with all nations to rid them from the planet. If they continue to exist, it is hard to imagine that they won’t eventually be used—with devastating consequences. And that is unacceptable.
Dr. Gronlund’s research has focused on technical issues related to nuclear terrorism and fissile material controls, U.S. nuclear weapons policy and new nuclear weapons, space weapons, and ballistic missile defenses. She holds a Ph.D. in physics from Cornell University and is a fellow of the American Association for the Advancement of Science and the American Physical Society.