I posted this on another site this eve and it was deleted I suppose because it wasn't in line with the bitching and complaining about todays' wild market dead cat bounce. I suggested that an X7-Class CME if directed toward earth could knock out satellites, the internet, and the ability for people to buy gold and silver bullion from their dealers on line or over wireless and landline phones.
Today an X7-class corona mass ejection (CME) occurred on the sun today and was the most powerful of the solar cycle 24 (several years per cycle). Needless to say a large X-class could be a extermination event at one extreme and could shut down commerce for months at the other end with populations going into chaos. I just thought I'd publish this for those interested. If you value your existence watch this site for the next couple years. On average a CME takes about 2 days to arrive on earth, just to give you a reaction time line. Note CMEs also include nasty X-rays and proton bursts which are harmful in large doses.
.....is like worrying about an extinction level asteroid hitting Earth. Coronal Mass Ejections are relatively common occurrences. They tend to be more common and powerful during Solar Maximum (we are moving towards maximum now) The worst Solar Flares have indeed damaged power distribution grids and sensitive electronics like those in satellites.
If a CME were large enough to cause "extermination" as you put it, I doubt people will be worrying about how to buy gold and silver via online dealers. Hell, I've been hoping for a CME large enough to smoke cell phone satellites for the last 15+ years!
My personal experience with CME's comes in the form of hundreds of magnificent displays of Northern Lights. I live at 47 degrees north latitude and a big CME causes a coronal aurora directly overhead which is an event everyone must see before they die! Better than any manmade light show you will ever see. The last really big CME caused aurora that could be seen from positions on the Equator!