Could the sun reach a state that emits constant solar flares and CMEs?

Question

Basically, I want to create an apocalyptic event that knocks out most electricity, for a long time, hundreds of years at least. Electronic devices that do work would be extremely rare, and people eventually give up trying to create new tech because a CME would render it useless within the week/month.

Is there any way the sun could become active in this way? Maybe near the end of its lifespan?

Also, would it damage the Earth's atmosphere, change the climate, or raise radiation levels enough that Earth would become uninhabitable?

Answer 1

Confusing Geomagnetic Storms with Electromagnetic Pulses

So you want something that makes electricity difficult and that destroys electronics. The problem with that is you cannot achieve that by your proposed scenario.

A geomagnetic storm is something that lasts for hours. Geomagnetic storms will induce long lasting direct currents in very long conductors due to slow but significant changes in the magnetic field, in essence wreaking havoc on power transmission systems, metal telephone lines and similar. This does not affect small devices other than that they might suffer over- or under-voltages when connected to these grids

An electromagnetic pulse on the other hand is an extremely short spike of voltage. A large power grid or communications systems can handle that, if designed properly, with protection mechanisms that either soak up the extra energy and ride out that short pulse, or just trip out the lines to protect sensitive structures. Small un-shielded devices however — like electronics — cannot handle this very well and the spike will "fry" the semiconductor components.

Coronal Mass Ejections cause geomagnetic storms. They do not cause electromagnetic pulses.

Also worth noting is that it is not the increase in solar activity that causes geomagnetic storms but changes in solar activity, pulling and knocking the geomagnetic field lines about in a chaotic manner. And the faster is changes, the higher direct currents you get. So what you are looking for is not necessarily powerful CMEs but instead rapid changes in solar activity. You want CMEs that rise and disappear quickly.

Also worth noting is that if we were ever subjected to a constant geomagnetic storms we would soon adapt and ruggedise our transmission lines to deal with it. The fluktuations are slow enough for us to deal with it.

Answer 2

Plausible

Given how much we understand about stellar mechanics, a sudden, century-long increase in activity is not something that could be ruled out.

The first question is 'are geomagnetic storms that bad?' The answer is, we don't really know. There haven't been many bad ones affecting modern electronics. A big one in 1989 knocked out power in Quebec, but that isn't that big of an area, and the damage was repaired quickly.

The second question is 'could they be worse?' The geomagnetic storms that do hit Earth are like a super-powered solar wind consiting of charge particles. Since they are called a Coronal Mass Ejection, most of the particles discharged are hydrogen atoms (protons, basically) and electrons, with some alpha particles mixed it. The more dangerous parts of a nuclear weapon's EMP are caused by gamma radiation. If a huge gamma burst hit the Earth's atmosphere, it would effectively be worldwide EMP blast, at least on the side facing the sun.

The last question is "is that possible?" Well, solar flares do cause increased gamma emission, but the causes of solar flares are poorly known. So it is hard to say if something external could trigger them. It seems likely that high gamma emission has not happened in the past, because there would probably be evidence of that on Earth.

Far out speculation

One thing that cosmically causes gamma emission is accretion of one object into another, like a star being sucked into a neutron star or black hole. For example, if a Jupiter sized planet appeared out of deep space, approached the sun too closely, and then broke up into a ring, the accretion of the ring material into the sun would cause intense X-ray and/or gamma emission for a (geologically) short period of time; as long as it took the ring material all to settle into the sun.

Answer 3

Kingledion's answer is more plausible than the post makes it sound. It would take really bad luck, but if there is a gamma ray burst caused by a black hole slowly eating a massive star, and we happen to be in the path of those gamma rays. We could be fried.

https://en.wikipedia.org/wiki/Gamma-ray_burst

There was a TV show "Mega Disasters" aired 2007 (Season 2, episode 2) that discussed this possibility, and speculation that this sort of event could have been responsible for one of the mass extinctions. What you are aiming for is a more mild dose over a longer time period. If a Jupiter sized planet appeared out of deep space, the gamma ray emission will be the least of our problems. Maintaining a stable orbit and avoiding the new planet will be more than enough fun for all.