Wow! Getting ready for all kind of scenarios require time, money and knowledge. Tonight we are discussing different scenarios that are likely (or not?) to bring a massive disruption in North America...
Massive Electromagnetic Pulse
Super Volcanos & Volcanic Winter
Global System Collapse
Geomagnetic Reversal - Or: Earth Pole Inversion (seriously! Click to check this article and scroll down to Effect on Biosphere)
The Sun Running Out of Fuel (4-5 billion years to go though... humans will screw it up before then!)
1. Electromagnetic Pulse (EMP) - This is a very strong electromagnetic radiation not dangerous to humans per se, but that has the ability to fry electronics containing transistors, electrical node transformers of the grid. The most damaging impact would happen on bigger electronic devices like electrical grid transformers. Most fear either a natural EMP coming from the sun. We have experienced EMP from solar flares that has impacted the grid in local areas, but the fear of a more important sun pulse can be considered real. The other source, well, would come from humans...
A real threat in the USA would require a specially designed nuclear bomb to explode at around 200 miles of altitude to have a massive measurable impact on the grid. It is not a small bomb hidden in someone's suitcase... It requires a missile capable of reaching space in a very specific location. This reduces the number of countries that would be capable to throw an effective EMP bomb.
Some say that in the case of a nuclear war, the enemy would want to first neutralize the measures to respond by first detonating an EMP nuclear weapon... quite scary! Is it likely to happen? Hard to tell, because the public does not know who has such a weapon and what the real damages could be. I like to think that the radiation emitted by such a bomb would have massive long term impact, which can be more devastating that the electromagnetic pulse itself.
Here is an interesting review by the Canadian Preppers channel: