U.S. President Donald Trump and North Korean leader Kim Jong-un made the news in recent weeks, threatening each other with nuclear ruin by means of long-range missiles.
But what sort of damage would a nuclear detonation on New York, Los Angeles, Washington or London actually inflict? Are North Korea’s missiles accurate enough to attack an American city, and if so, what are the chances they would actually succeed in striking their targets?
Much of the data that can answer these questions is publicly available, and reasonable guesses can be made about still-classified data. But making intuitive sense of it, even for experts, can be surprisingly difficult.
That's why Stevens Institute of Technology professor and historian of science Alex Wellerstein created and manages several software tools that make it easier to test scenarios and depict the terrible power and potential of the world's vast nuclear arsenals.
Wellerstein’s NUKEMAP tool, which works in any web browser, can simulate a nuclear detonation anywhere on the planet. At the click of a "detonate" button, the software produces simulations and visualizations of blast zones, mushroom clouds and fallout plumes spreading through the air — plus fatality and injury estimates — atop Google Maps renderings of cities.
Users can experiment with a wide range of nuclear weapons, from small "backpack bombs" to large-scale thermonuclear weapons (such as a hydrogen bomb). The weapons it can simulate range from those in the earliest days of the nuclear age to those currently deployed by nuclear-capable nations. Wellerstein’s simulator has been highlighted by a variety of news organizations, including The New York Times.
"Being told a certain nuclear weapon emits 500 rem of radiation over a given radius means little to the average person,” he explains. "But when you pair that with an illustration of a cloud spreading over a city they live in, along with a qualitative description of the effects and casualties, the picture suddenly becomes much clearer."
Wellerstein’s newly unveiled MISSILEMAP does much the same for long-range missiles. Users select launch sites, missiles and targets according to the range of each missile. The accuracy of each missile, the explosive power of its warhead and the odds of hitting its target are instantly calculated and displayed.
"We still don’t know exactly what North Korea’s missiles are capable of," he cautions. "But you can plug some fairly conservative numbers into the MISSILEMAP and see that hitting Guam accurately would be somewhat difficult but not impossible, while hitting Los Angeles is easy — if they have the range."
A North Korean missile aimed at San Francisco, for example, could potentially kill or injure at least a quarter-million residents and obliterate the city's downtown district according to the MISSILEMAP and NUKEMAP simulations.
Public data, powerfully programmed
While Wellerstein created the visualizations and integrated the data, he didn't need to create the math from scratch; that had already been done by the U.S. government decades ago, and later declassified as open data.
The professor dove into national defense archives and obtained painstaking blast-zone research derived from postwar U.S. government studies of the detonations at Hiroshima, Nagasaki, the Nevada Test Site and the Marshall Islands.
"Those Cold War calculations were daunting for the computing machines of the 1960s, but now easily run in a modern web browser," he explains.
New missile model simulates long-range attacks and local consequences
MISSILEMAP, a new tool Wellerstein rolls out this August, works with more complicated calculations, assumptions and defense concepts such as Great Circle trajectories, Circular Error Probable (a measure of missile accuracy) and the Single Shot Probability of Kill (a measure of the likeliness of a target to be destroyed by a launched missile). Coordinates are entered, and a missile's maximum target range appears on a world map; the resulting data can also be exported to NUKEMAP to help visualize the consequences of a successful missile launch on, say, Los Angeles.
"Again, this is public data," he notes. "All models used in the creation of these tools are adapted from government research that was paid for by U.S. taxpayers. It's good to put them to public use again."
The images and casualty figures can be shocking, and they are receiving wide attention. Media small and large, from the Los Angeles Times to Popular Science to London's The Telegraph — even former U.S. Defense Secretary William J. Perry — have referenced or published images from Wellerstein's research.
What's most striking, Wellerstein says, is the historical perspective these new visualizations give.
"In the NUKEMAP simulation, a Hiroshima-type bomb detonated in Manhattan punches out the center of the downtown, yes, but observers only a mile or two away mostly experience shattered windows," he notes. "A hydrogen bomb, however, destroys the entire metro area, with tremendous casualties and a huge mushroom cloud."
Wellerstein's students audibly gasp when they see these visualizations unfolding, he says.
"If you can make undergraduates exclaim verbally in class, you know you must be doing something powerful," he points out.
But the students also begin to understand, in a visceral way, the real gravity of the modern nuclear threat
"Even a small modern nuclear weapon is many times more powerful than the largest weapons ever used in World War II," concludes Wellerstein. "It's my hope that NUKEMAP and MISSILEMAP help everyone begin more serious and careful conversations about the real power of these weapons, not only among the public but among national and international leaders."