The Carrington event happened in the 1850s because of a Coronal Mass Ejection (CME) on the sun. This video speculates on the effects of a similar event today. For more information see: Coronal Mass Ejections.
“The Doomsday Book” by Marshall Brain lays out this scenario in amazing detail and offers solutions to prevent this doomsday scenario from unfolding. You can order the book today on Amazon and other retailers.