One of the scary things I learned in writing my thriller Patriarch Run is that our civilization has unwittingly evolved to become absolutely dependent on the power grid. It's not an exaggeration to say that if the grid went down today and didn't come back up again, most of us would die. If you're curious about how that can be, you can read my Discussion Guide.
What's frightening about our dependence on widely-available, reliable electrical power is that there are several mechanisms of destruction that could deny us the grid, including weather created by the sun.
Several leading scientific organizations (NASA, NSF and NOAA) gather annually at the Space Weather Workshop near Denver to discuss, among other things, this type of threat. For example, Kazunari Shibata gave a presentation at the 2015 Space Weather Workshop titled Superflares on Solar type Stars and Their Implications on the Possibility of Superflares on the Sun.
Shibata's presentation covered the usual topic of the 1859 Carrington Event which was the largest Coronal Mass Ejection (CME) of the last 200 years. A CME is a regular event in which the sun's corona ejects a large amount of plasma into space. When such an ejection is directed at Earth, it interferes with Earth's magnetic field and, consequently, our electronics. If a similar CME were to occur today, it could take down power grids worldwide.
Although a Carrington-type event poses a massive destructive potential relative to our civilization, Shibata speculated that the Carrington Event might be a small CME compared to what's possible.
If empirical statistics rule of solar flares is applied to much larger flares (superflares), then the frequency of superflares with energy 1,000 times larger than the largest solar flares might occur once in 10,000 years.
Because of the catastrophic potential of such an event, Shibata assembled a research team to further assess the threat. Shibata's team used NASA's Kepler satellite to study a large sampling of stars similar to our sun. After crunching the data, the team determined that a superflare 1,000 times larger than the Carrington Event might occur on our sun much more frequently than Shibata originally hypothesized: once every 800-5,000 years.
In his presentation at the 2015 Space Weather Workshop, Shibata surmised that such a superflare would devastate of our civilization. The following disasters were introduced as probabilities:
All artificial satellites would be damaged
All astronauts and some airline passengers would be exposed to fatal radiation
Ozone layer depletion would occur
Radio communication trouble would occur all over the world
Global blackout would occur on all over the Earth
All nuclear power stations would lose electricity and hence be in a state of meltdown
CMEs are note worthy threats because they require no human intent, no malice. There are several other mechanisms of destruction that could bring down the power grid, but those eventualities are contingent on a will to destroy us. If you're interested, you can read more about this topic at my Discussion Guide.