https://www.spaceweather.gov/noaa-scales-explanation

Here are some of the risks that are currently unfeasible to mitigate:

G5:

> Widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.

S5:

> Satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible.

---

One extremely unlucky solar event can set us back for years, and there is absolutely nothing we can do to prepare for it long term. Our best predictive models give us a couple of days notice.

In a sense, we're more prepared for an asteroid collision (not by much) than a solar event.

> 1. If it were true, I expect it would be a national security concern, and quickly remedied

You can’t prepare for everything, and even if you could remedy it, there are loads of more likely disaster scenarios that would get higher priority.

> If it were true, I expect it would be a national security concern, and quickly remedied

I dunno... things happen that expose these risks and lead times for replacement equipment can push out to 2-3 years.

https://en.wikipedia.org/wiki/Moore_County_substation_attack

https://en.wikipedia.org/wiki/2021_Texas_power_crisis

https://pv-magazine-usa.com/2026/09/02/u-s-bulk-power-equipm...

Not sure that I can speak to everything, but I did take a course specifically on space weather + its impacts on Earth and have some context I can maybe share. For your first point, you are correct it is a national security concern. There are standards already in place that aim to address/mitigate potential disruptions from solar storms/ space weather, but the concern is/would be if these standards are sufficient for an extreme event like Carrington or this 1840s example. From a national security perspective, it's also not a risk that comes from an adversary, it's not something Russia/China/Iran/[insert country] can do to us, it's just an environmental consideration, and could happen to anyone (and if any one country is effected in a significant want, it's likely that others would be facing some consequences of the storm as well - especially w.r.t. satellites). From a strategy perspective, it's similar to if an earthquake destroyed the 3 gorges dam - it's obviously a risk but it's categorized a bit differently. It's more about how quickly can you re-establish normal operations rather than how do you fully prevent it. Obviously mitigation is part of that, but it changes where it gets prioritized.

And to segue into your later points, the reason it's unknown if the current standards would be sufficient is because these sort of events, and how they interact with a continent-sized electrical/ transmission systems (the grid), is a pretty complex problem. It's also one that we can't exactly test in a lab or controlled environment beforehand with a super high degree of confidence given the scale that the phenomenon takes place at (the whole planet). EMI testing that occurs for most tech products today isn't super focussed on the currents induced by a solar storm, which are low frequency/quasi-DC/much less predictable (the effects vary geographically and in time-scales/patterns that "typical" EMI/EMC does not).

Some googling lead me to a NOAA doc that says GIC's "quasi-DC ... currents flow through transmission lines and enter/exit the power grid through grounded transformer neutrals" which to me reads that simply having a neutral line isn't sufficient, but I'm not an EE and could be misunderstanding what you're saying and what this doc is speaking to.

The good news is that events like this are relatively rare, confined (generally) to certain parts of the 11-year solar cycle.

> 1. If it were true, I expect it would be a national security concern, and quickly remedied

If only the world worked this way. Until something happens, a lot of potential problems remain potential problems rather than getting remedied. Especially when it'll be expensive to fix.

>1. If it were true, I expect it would be a national security concern, and quickly remedied

It was known in the early 2000s and they've been working on it for decades. Presumably things are better now.

> 4. As long as there’s a neutral line, i think any common mode should be rejected, in which case this should be fine?

The (grounded) neutral conductor actually completes the circuit, a wye/star transformer has a grounded neutral and the primary and secondary neutral terminals are bonded. The return path is ground and all of the transformers are linked together via the grounded neutral.

Apparently this can be mitigated by wiring a capacitor into the grounded neutral path of a wye transformer.

I’m not an EE, just an electrical PM who knows enough to be dangerous :)

Hydro Quebec was very strongly hit, primarily due to its long power line runs:

https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm

Supposedly, they've hardened things, lots of info on what they've done here:

https://news.hydroquebec.com/news/press-releases/all-quebec/...

I have zero idea of 1989 vs the event in 1840 though.

>1. If it were true, I expect it would be a national security concern, and quickly remedied

You live on Earth correct :) just joking.

Just look at what has been done for Climate Change, we knew for 50, probably 70 years what fossil fuels are doing to Earth. Plus a good estimate was know when Climate Change would affect the Earth. Here we are heading to +3.5C, probably 4C.

Since when a Carrington type event will happen is unknown, do you really think we would prepare for it ? That would cost real money, maybe taking wealth from the super rich.