James,
The magazine Infoworld is a fairly trusted source in the information technology (IT) field. They recently posted an article titled, “Tech apocalypse: Five doomsday scenarios for IT”.
Here is a quote:
“What could happen [from a wide scale EMP attack]: Workstations? Dead. Data centers? Gone. Cell phones might still work, but the cell towers probably won’t, rendering them useless. Your car won’t start. A large enough attack will also shut down automated controls at power substations, leaving everyone in the dark. Think pre-industrial revolution days. In our scenario the New York Stock Exchange shuts down, causing shock waves to reverberate throughout worldwide markets.”
That is not bad for a mainstream IT magazine, though in this scenario they downplay the aftermath. in my opinion. However, they call it “higher than you might think” when talking about chances of this happening.
Their description of the effects of a massive coronal ejection (their last scenario) is pretty good, with a prediction of a recovery time of 4 to 10 years, if at all. – MP