My fear has always been a super volcano eruption, like Yellowstone. It would disrupt the whole planet. I've had this feeling that our world is going to change drastically and we won't have power nor cell phone/internet service. I feel that we should make plans with our distant family members to meet up at certain places in case of disaster. Choose a few different areas in case some become inaccessible. Have a workable plan and hope it will never be needed.