Coming down to earth: what if a big geomagnetic storm does hit?

Abstract

I devoted the first three posts in this series to describing geomagnetic storms and assessing the odds that a Big One is coming. I concluded that the iconic Carrington superstorm of 1859 was neither as intense nor as overdue for an encore as some prominent analysts have suggested. (I suppose that’s unsurprising: those who say more-alarming things get more attention.) But my analysis is not certain. To paraphrase Churchill, the sun is a riddle, wrapped in a mystery, inside a corona. And great harm would flow from what I cannot rule out: a blackout spanning states and lasting months.

I shift in this post from whether the Big One is coming to what will happen if it does. And here, unfortunately, my facility with statistics does less good, for the top questions are now about power engineering: how grids and high-voltage transformers respond to planetary magnetic concussions.