Telecom networks depend on GPS for timing, however they generally have backup Rubidium atomic clocks in their central offices to carry them through a GPS outage. I suspect that ATMs have some form of timing failover as well.I know we don't have 100% prediction capability for solar flares. And that in the past some things have escaped observation and were known too late or when they were already on the way.
Sooner or later there will be another Carrington event and its consequences could be disastrous.
The collapse of the GPS network alone would bring immense inconvenience.
Once I read that without the GPS network the ATM network does not work, I do not know if this is true
(it was said that without the GPS system the time synchronization does not work and the ATM network goes haywire)