Most of the information needed to recover from such an event exists only in digital form on magnetic media. These days, most of it probably exists only in "the cloud", which is this happy place immune from the electromagnetic effects of coronal mass ejections and very easy to access after the power grid goes down.NASA has a post discussing recent research into CMEs which is required reading:
Analysts believe that a direct hit by an extreme CME such as the one that missed Earth in July 2012 could cause widespread power blackouts, disabling everything that plugs into a wall socket. Most people wouldn't even be able to flush their toilet because urban water supplies largely rely on electric pumps.An extreme CME called the "Carrington Event" actually did hit the Earth in September 1859:
Intense geomagnetic storms ignited Northern Lights as far south as Cuba and caused global telegraph lines to spark, setting fire to some telegraph offices and thus disabling the "Victorian Internet."And:
A similar storm today could have a catastrophic effect. According to a study by the National Academy of Sciences, the total economic impact could exceed $2 trillion or 20 times greater than the costs of a Hurricane Katrina.Not to worry, because:
In February 2014, physicist Pete Riley of Predictive Science Inc. published a paper in Space Weather entitled "On the probability of occurrence of extreme space weather events." In it, he analyzed records of solar storms going back 50+ years. By extrapolating the frequency of ordinary storms to the extreme, he calculated the odds that a Carrington-class storm would hit Earth in the next ten years.Only 12%. I'd say that CMEs need to be part of the threat model of digital preservation systems.
The answer: 12%.