This has actually been discussed in great detail by scientists and engineers at a conference. The resulting PDF is here: http://lasp.colorado.edu/home/wp-cont

This has actually been discussed in great detail by scientists and engineers at a conference. The resulting PDF is here: http://lasp.colorado.edu/home/wp-content/uploads/2011/07/lowres-Severe-Space-Weather-FINAL.pdf http://lasp.colorado.edu/home/wp-content/uploads/2011/07/low... The TLDR is that it'd be really bad, but I encourage you to read it -- it's pretty fascinating, given that geomagnetic storms of an intensity great enough to take the first world off the electrical grid for a few years isn't just geologically common, it's historically common.