North Korea's Plenty Scary Without an Overhyped EMP Threat

Angst over a potential electromagnetic pulse attack bubbles up every few months, and it’s easy to understand why. The EMP impact envisioned by people who have studied it closely would be downright apocalyptic: a decimated US power grid, and up to 90 percent of Americans dead within a year. It doesn’t help, either, that North Korea recently invoked the specter of an EMP attack, and seems increasingly like it would have the wherewithal to pull one off.

In broad strokes, if you explode a nuclear weapon at high altitude, it generates an electromagnetic pulse, which in turn can disrupt electronics ranging from cars, to street lights, to the US power grid itself. By what degree depends on whom you ask.

Scary stuff, especially that 90 percent number, which was first offered by representative Roscoe Bartlett in a 2008 Congressional hearing, and backed by a physicist—and leading voice in the EMP issue—named William Graham. But Bartlett himself sourced the figure from a work of science fiction, William R. Fostchen’s One Second After. And while an EMP surge, be it from a hydrogen bomb detonated high above North America or powerful solar storm, would surely impact daily life, the extent of the possible repercussions remains uncertain. At least where North Korea is concerned, that lack of an assured outcome should help ease—if not totally erase—EMP concerns.