It would be good business for the news industry: sky lights, plane crashes, exploding grid transformers, city blackouts, satellite damage, long, electricity-carrying wires would spark, start fires and and send signals when they are switched off. Burning buildings, dead people, everything.
big flares occur about every 100 years. the last was the Carrington event in 1859. It triggering telegraph malfunctions (even giving operators electrical shocks) and caused some telegraph pylons to suddenly spark and catch fire.
A surge in solar wind can blow out power transformers by melting the coating that insulates copper windings and by melting the copper itself, especially in highly interconnected regions (i.e. the East Coast), transformer failures can trigger cascading effects, spreading power outages over wide areas.
a flash of light is seen from the sun 17 hours in advance of the magnetic storm, and sunspots are monitored for activity.
If a massive CME were spotted, 3-day forecasts give us some lead time: there are some measures electric utilities could take to protect their equipment, such as quickly disconnecting transformers. Polar flights, which travel at the highest altitudes, could be rerouted to avoid contact with damaging solar particles, and some satellites could be switched into a safe mode to minimize damage. Here on Earth, at the very least, we’d have some time to prepare for potential power blackouts and other problems.
Given the scope of our current technological infrastructure, it’s been estimated that the next Carrington-scale event (which happens roughly once every 100 years) will cause upwards of $2.6 trillion in damage across the globe, and require four to ten years for complete recovery.
Scientists studying tree rings found a sharp increase in the amount of radioactive carbon-14 recorded in the rings of ancient Japanese cedar trees between 774 and 775. Carbon-14 can be created by cosmic ray particles arriving from space, and the 774 incident could have been a solar flare.
there is a list of big solar storms here: