On September 1, 1859, a massive solar flare struck the Earth, resulting in beautiful auroras but also inducing currents in telegraph wires causing them to spark and start fires. Hours earlier amateur astronomer Richard Carrington was observing the sun and noticed large sunspots giving off a brief bright flare. In 1859 the telegraph was about the only electric infrastructure we had. What if a Carrington-type event struck today?

Solar flares result from the complex magnetic fields of the sun. Gas in the sun is so hot the electrons are stripped from the hydrogen, resulting in a plasma. Since plasma is therefore made from ions, it carries an electric charge, and when electric charges move they generate a magnetic field. Magnetic fields further induce electric current.

Sometimes the magnetic fields near the surface of the sun interact in such a way that they give off an explosion of energy, called a solar flare. There is also something called a coronal mass ejection, in which a bubble of hot gas erupts from the sun’s corona in a fashion similar to a solar flare. CMEs and solar flares often occur together, but not always, and their causal relationship is not clear.

Solar flares and CMEs cause a pulse of energy in the solar winds. Charged particles racing from the sun, if they were aimed in our direction, would strike the Earth about 17 hours after the visible solar flare, so we would have some warning. The charged particles would interact with the Earth’s magnetic field, causing aurorae.

More importantly, the magnetic fields induced by the ions striking the earth would induce powerful currents in any conductive material. Any electronic device that was not shielded would be fried, its components damaged or even melted.

Think about what this would mean for our civilization. Every computer would be gone. Our satellites would be destroyed also. The power grid would go down. Communications would be gone.

Essentially we would be plunged into a pre-electrical age. I was recently asked what would happen to jets in the sky. Their electronics would be fried also, knocking them out of the air. Of course, there would be sufficient warning to ground all aircraft.

Modern cars with their electronics would also not function. We would all be trapped, without communication, transport, or electricity. The damage would be so extensive it could take many months to restore basic services. Damage would be in the trillions of dollars. It’s hard to imagine there wouldn’t be massive loss of life and suffering as a result.

What are the chances of a Carrington event hitting. One published estimate is that there is a 12% chance of a similar event occurring in a 10 year span (at least between 2012 and 2022, this varies with the solar cycle). We’re not talking about the possibility of an asteroid striking something in the next 100,000 years – there is very likely to be such as event in the next 100 years.

In fact, a CME of the size of the Carrington event occurred just in 2012. Luckily, it missed the Earth.

So what should we do about it? First we need to have a reliable early warning system. Sun activity monitors are necessary to guarantee we see the solar flare, and then immediately distribute the warning throughout the world.

But of course we need to have some way to respond to the warning. Grounding aircraft and stopping any activity that would be dangerous if equipment stopped functioning is a start. What we really need to do, however, is shield critical electronic infrastructure against strong external magnetic fields.

This is possible. The military also does this, as nuclear explosions release an electromagnetic pulse with similar effects. We would need to shield our satellites against solar flares, and they need the ability to turn away from the sun and quickly fold their solar panels (if they have them) and close up any exposed electronics. We would also need to shield the power grid and build in safety shut offs.

Consumer electronics are another matter. I’m not sure how much I would pay for a shielded computer, but I might buy a shielded hard drive to back up my data. Would you pay a few hundred dollars extra to have your car’s electronics shielded from an EMP or Carrington size solar flare? That would be an interesting upgrade.

The cost of protecting our electronic infrastructure from a Carrington event would be billions of dollars, but the cost of a Carrington event would be orders of magnitude greater.

I suspect that any attempt to predict what would happen should such an event occur is an underestimate. It’s difficult to trace the sequence of progressive collapse that would happen to civilization. Further, it’s actually likely that this might occur.

This is definitely an investment in prevention that seems worth the probable expense.