A Coronal Mass Ejection (CME) of Carrington-scale magnitude — or larger — would induce catastrophic electrical currents in every long conductor on Earth's surface. Power grids, undersea cables, railway networks, and pipelines would suffer simultaneous cascading failures.
The 1859 Carrington Event, the most powerful solar storm in recorded history, caused telegraph systems to catch fire. A comparable event today would destroy an estimated $2 trillion in infrastructure within the first 24 hours — and modern civilisation depends on an electrical grid that takes years to rebuild.
The true danger is not the storm itself but the collapse of supply chains that follow. Within weeks: no fuel distribution, no food refrigeration, no medical equipment, no communications. Within months: societal breakdown at a scale that could erase centuries of accumulated knowledge and population.