Not GP but it's a cascade failure mode with theoretically no upper bound in how much chaos it could cause. A toilet paper shortage caused millions to lose their goddamn minds, what do you think having no refrigeration on a world scale for even a week would do? A CME could potentially fry enough equipment that we would be left in in the dark and unable to repair for months, just due to availability of parts. I believe those estimates are at current production rates, too. If the supply chain and global comms are compromised, it's even harder.
It's definitely at the sweet spot of "terrifying" and "completely plausible."
My 40% is based on that information. I'm gut-extrapolating to the next few decades, with the understanding that large devastating flares occur every few hundred years.
Society is so incredibly dependent on technology that is not EMP resistant and if a solar flare knocks out most of our electronics the bottom is going to fall out. No phones or internet to figure out what's going on, no cars since the onboard electronics are needed- same with trucks, trains etc. Can't go to the grocery store and buy food with your debit card, can't get cash from the bank, grocery store isn't going to get shipments anymore etc.
Our dependence on it all puts us on really fragile ground given that we know there have been sun events in the last 150 years that would obliterate everything we have today
I have read that the dangers of EMP's are greatly overstated and they could damage stuff, but mostly the power grid, since you need long lines to induce sufficient power for it to matter.
It's definitely at the sweet spot of "terrifying" and "completely plausible."