How many 'super nukes' would it take to destroy the world?

Shortly after the end of World War II, the scientists who developed the atomic bombs dropped on Japan tried to envision the kind of nuclear event that could lead to the destruction of not just cities, but the entire world.

nuclear weapon, mushroom cloud,

The U.S. detonated a ‘super bomb’ in an above ground test in 1954. (Photo: Department of Energy)

A declassified document shared by nuclear historian Alex Wellerstein gives the verdict that scientists at the Los Alamos laboratory and test site reached in 1945. They found that “it would require only in the neighborhood of 10 to 100 Supers of this type” to put the human race in peril.

In 1945, the Los Alamos scientists concluded it would only take between 10 and 100 “Super” bombs to end the world. pic.twitter.com/01I8ypmIP0

— Alex Wellerstein (@wellerstein) December 15, 2014

They reached this conclusion at a very early point in the development of nuclear weapons, before highly destructive multi-stage or thermonuclear devices had been built. But the scientists had an idea of the technology’s grim potential. “The ‘Super’ they had in mind was what we would now call a hydrogen bomb,” Wellerstein wrote in an email to Business Insider.

At the time, the scientists speculated they could make a bomb with as much deuterium — a nuclear variant of hydrogen — as they liked to give the weapon an explosive yield between 10 and 100 megatons (or millions of tons’ worth of TNT).

Also read: That time Jimmy Carter saved Canada from nuclear destruction

For perspective, the atomic bombs dropped on Hiroshima and Nagasaki had a yield of around 15 kilotons, or 0.015 megatons. These theorized bombs were several orders of magnitude more powerful than those that wrought destruction on Japan earlier that year.

The apocalypse brought on by these 10-100 super bombs wouldn’t be all fire and brimstone. The scientists posited that “the most world-wide destruction could come from radioactive poisons” unleashed on the Earth’s atmosphere by the bombs’ weaponized uranium. Radiation exposure leads to skyrocketing rates of cancer, birth defects, and genetic anomalies.

The Los Alamos scientists understood the threat that airborne radiation would pose in the event of nuclear war. “Atmospheric poisoning is basically making it so that the background level of radioactivity would be greatly increased, to the point that it would interfere with human life (e.g. cancers and birth defects) and reproduction (e.g. genetic anomalies),” says Wellerstein. “So they are imagining a scenario in which radioactive byproducts have gotten into the atmosphere and are spreading everywhere.”

Wellerstein says that this fear of widespread nuclear fallout was hardly irrational and that concerns over the atmospheric effects of nuclear detonations were “one of the reasons that we stopped testing nuclear weapons aboveground in 1963, as part of the Limited Test Ban Treaty.”

Taking both of the estimated scales to the extreme — 100 superbombs yielding 100 megatons of fission each — would result in a total yield of 10,000 megatons. As Wellerstein notes, that’s the same amount of fission that Project SUNSHINE determined was enough to  “raise the background radioactivity to highly dangerous levels” in a 1953 study.

That degree of nuclear power — though not necessarily accompanied by the radioactive component critical to meeting the fears documented here — rested in the hands of both the U.S. and Russia during the Cold War.

russian nuke nuclear weapons

A deactivated Soviet-era SS-4 medium range nuclear capable ballistic missile displayed at La Cabana fortress in Havana, on Oct. 13, 2012. (Photo: Desmond Boylan/Reuters)

In recent decades the total yield of U.S. and Russian nuclear weapons has fallen, such that “the threat of over-irradiating the planet is probably not a real one, even with a full nuclear exchange,” Wellerstein wrote. “A bigger concern is the amount of carbon that would be thrown up in even a limited nuclear exchange (say, between India and Pakistan), which could have detrimental global effects on the climate.”

Back in 1945 the Pentagon had speculated that it would take a few hundred atomic bombs to subdue Russia.

That thought experiment had a strategic bent. But the 1945 estimate seems to have advised caution in the new,  uncertain nuclear age.

The scientific push to learn more about the destructive weapons that were so hastily researched and used in the 1940s resulted in important insights as to the consequence of their use. Nuclear weapons aren’t just horrific on the intended, local scale. They can carry consequences on the planet’s ability to foster human life, whether that’s by contributing to the greenhouse effect or irradiating it beyond habitability.

These warnings aside, [the] U.S. did end up detonating a “super bomb” in above-ground tests. The U.S. detonated a 15 megaton device in the infamous Castle Bravo test in 1954. And the Soviet Union’s Tsar Bomba, detonated in 1961, had as much as a 58 megaton yield.

An earlier version of this article was written by Pierre Bienaimé.

TOP ARTICLES
This is how the Army Corps of Engineers is helping Puerto Rico

The Army Corps of Engineers is working to restore power to the island of Puerto Rico after four major hurricanes devastated these parts of the US.

This Marine is more operator than you'll ever be

One Marine isn't taking his life changing injury sitting down. In fact: he's running. Follow Marine Rob Jones as he runs 31 marathons in 31 days.

This is the agenda for Mattis' Indo-Asia-Pacific tour

Secretary of Defense Mattis is touring the Indo-Asia Pacific region to strengthen ties with ally countries and underscore our commitment to each of them.

This is the reason Russian and Western tactics are changing

Russia might be stepping up its War Games game, but the United States isn't having any issues keeping up. Even their Krasnodar can't get past us.

Here are the top conspiracy theories surrounding Kennedy assassination

Ahead of the release of 3,100 documents pertaining to the Kennedy assassination, here the top assassination conspiracy theories people are talking about.

Air Force says no plan to recall retired pilots

The Air Force says it has no intentions of recalling retired pilots to address personnel shortages, though it appreciates the ability to do it if it wants to.

Here is how Burke-class destroyers will be able to zap incoming missiles

Burke-class destroyers, already packing a formidable punch, could add lasers, improving capabilities against UAVs, missiles, and even piloted aircraft.

11 'totally real' things you should send your boot to find

Sending the FNG out to find things isn't malicious. It may look like hazing — but you're teaching them a little bit more about the unit. Isn't that nice?

This is the new version of the pup tent

This is not your grandfather's pup tent. Litefighter has developed a complete shelter that troops can carry, weighing in just over four pounds.

This is why Saddam Hussein's fedayeen troops wore Darth Vader helmets

Wondering why Saddam's personal militia wore all-black suits and ski masks in the middle of the desert all year 'round? It was to match their helmets.