Much of the planning for a severe space weather is based on the Carrington Event of 1859, the most intense geomagnetic storm in recorded history.
This created rapid variations in the Earth’s magnetic field that caused electricity to be generated in long wires.
Telegraph operators suffered electric shocks, pylons were seen to spark and some conversations between operators could carry on while batteries were disconnected.
All this happened a long time ago, but with today’s advanced technologies the effects of a similar event would be far more disruptive.
Satellites can be badly affected. Strong solar storms can cause the Earth’s atmosphere to expand out into space, which creates more drag for satellites. This can cause them to slow down enough for some to deorbit and fall back to Earth.
This is not just a theoretical risk – in February 2022 a solar storm led to the loss of 38 satellites, external.
Orbital changes of satellites also increase the risk of collision and space weather can also play havoc with sensitive electronics on board, causing malfunctions.
Radio communications can be badly impacted with GPS systems lost or disrupted for many days – so your car sat-nav could stop working, creating gridlock in cities.