Coronal Mass Ejections And EMP Pulses
The sun is currently at a low point in activity but that will ultimately change.
In 1989 much of Canada was blacked out by one and a worldwide one took place in 1859, back then, we only had the telegraph and that was fried. In 2012 (ironically) a major coronal mass ejection just missed the Earth. Something we really should try to prepare for but we seem to have that mentality, "If it ain't broke, don't fix it"