He claims that a “small nuke” could cause all that damage.
He does not know much about EMP or what type of weapon causes it, or how that weapon is deployed.
If what he says is true, then Starfish Prime or Argus would have seriously impacted Hawai’i or the American East coast, respectively. Starfish was about 170 kt. There is still some controversy about the hundred or so streetlights that went out on the Big Island, but aside from pretty lights in the sky, there was no effect that the civilians were aware of.
Without getting into too much detail, it takes a pretty big thermonuclear device, popping off with the right characteristics, to get an ideal EMP effect. Not every old nuke will do. Placement is important, too, both X-Y and altitude.
Considering that he believes in AGW, I think he’s just repeating some inflammatory stuff he heard.
If you think about it, if the EMP device is coming in from orbit, there’s not a lot you can do about it. You’d need to know what it was in advance, and get it as it descends from 500 miles down to 60 miles at orbital speeds.
Sputnik was scary because we had nothing to counter. Eisenhower went on the air a year later with a nose cone for a ballistic missile, and baldly said we caould drop one anywhere, anytime, so the puny orbital Sputnik was not a threat considering our ability to retaliate.
Military systems are hardened, and submarines are protected from most EMP by being immersed in a conductive liquid. Our ability to retaliate with nukes will not depend on commercial telephone systems or car ignition systems. Just like in Ike’s day, we can drop lots of big nukes pretty much where and when we want.