The fault in our star

How do you convince people and governments to spend money on preparing for a weather event that may only happen every few hundred years, but whose effects could be catastrophic without the proper precautions?

That is the challenge faced by solar and heliospheric scientists worldwide who are working on early warning systems for severe geomagnetic storms that could destroy electronic devices and knock out whole electrical grids.

Although it sounds like the hamfisted plot of a disaster film, a destructive geomagnetic storm of global proportions has happened before in recorded human history — we were just lucky enough not to be so reliant on electricity and electronics.

Known as the Carrington Event, the incident is named for one of two amateur British astronomers, Richard C. Carrington and Richard Hodgson, who independently observed and recorded a “super flare” in 1859.

Such severe geomagnetic storms are caused by coronal mass ejections (CMEs), a type of solar storm that ejects part of the Sun’s corona and is often associated with solar flares.

If the Earth and Sun are in magnetic alignment when a CME occurs, the plasma collides with our magnetosphere, causing a geomagnetic storm.

At certain intensities, this can cause beautiful phenomena like aurorae — the northern and southern lights.

This would often be accompanied by a moderate disruption in high-frequency (HF) and very high frequency (VHF) communications, which many militaries rely on for radio communications.

Despite what the names might suggest, HF and VHF signals are no longer considered particularly high-frequency in wireless communications. Cellular networks use even higher frequencies and wouldn’t be impacted except by the most severe geomagnetic storms.

However, more severe geomagnetic storms can also be incredibly destructive to electric grids and electronic devices.

During the Carrington Event over 160 years ago, telegraph operators reported receiving electric shocks, being able to send and receive messages even after disconnecting power, and witnessing sparks from telegraph pylons.

If a similar CME were to hit Earth today, the effects would be far more devastating as we have become totally dependent on electricity and electronic devices.

It could also have other negative impacts, including destroying artificial satellites orbiting the Earth by knocking out their electronics.

Additionally, the storm would heat the upper atmosphere, increasing air density and causing more drag on low Earth orbit satellites like Starlink, potentially causing them to fall out of orbit.

Airline passengers and crew would also be exposed to harmful radiation from the Sun, which arrives before the plasma from the CME. This radiation could cause DNA damage and increase cancer risk.

There have been smaller-scale magnetic storms in more recent years that give an idea of what to expect should a CME the size of the Carrington Event hit Earth again.

For instance, a less severe storm in 1989 caused parts of Canada’s electrical grid to fail in its Quebec province.

This raises some concerning geopolitical questions.

It’s one thing if a CME big enough to overload the whole world’s electrical systems hits the planet — but what if it’s only big enough to take down one country, continent, or hemisphere?

Our current early warning systems are also imprecise. They can give from a few hours to a few days warning.

Telling a country or group of countries they need to switch off their electrical grid and electronic devices for several days would cause significant economic damage and potentially leave them vulnerable to malicious actors.

If the geomagnetic storm then turned out to not be severe enough to warrant such a response, the sacrifice would have been for nothing.

However, ignoring the risk could leave a country even worse off, as restarting an electric grid is much less arduous than repairing and replacing every transformer that becomes overloaded and explodes.

While a Carrington Event represents a worst-case scenario and is relatively rare compared to a human lifespan, rarity should not be confused with likelihood. It will happen again — it’s just a question of when.

Extremely severe solar storms tend to happen near “solar maximum” — a period of heightened solar activity in the Sun’s approximately 11-year cycle.

The Carrington Event in 1859 and the CME that took down part of Canada’s electrical grid in 1989 all happened a few months before the solar maximum.

Two years before a solar maximum, in July 2012, Earth narrowly missed a Carrington-sized CME. Interestingly, it was ranked among the weakest solar maxima on record.

The Sun is currently near a solar maximum, and scientists have recorded increased solar activity in recent months, including several large CMEs that have caused severe geomagnetic storms.

One of the leading researchers in this field is Ruhann Steyn, a senior lecturer at North-West University with a Ph.D. in Space Physics.

As part of his master’s degree, Steyn derived new equations describing the Sun’s magnetic field. His doctoral research focused on the transport of highly energetic particles from the Sun to Earth, specifically for space weather prediction.

Steyn has emphasised the responsibility of the scientific community to educate the public about Carrington Events without causing undue alarm.

Scientists must be transparent about the uncertainties surrounding these events while explaining the importance of preparedness.

“Although it could happen this afternoon or in 150 years, it is something people should know about, and there should be a plan for it,” Steyn said.

Currently, the most effective defence against a Carrington Event is to proactively shut down vulnerable electrical systems.

However, issuing timely warnings is a significant challenge. According to Steyn, the time between detecting a CME and its arrival can vary greatly.

“If the configuration is very simple, it takes a lot less time to put it through a model, and you can have three days’ warning,” he said.

“If you’re unlucky, it can take a very long time for computers to crunch the numbers, and you may only get an answer three hours before the CME hits.”

Regarding the geopolitical concerns, Steyn said the international community is making a concerted effort to collaborate on space weather prediction.

Building trust and sharing data are essential for issuing effective warnings that can mitigate the impact of such solar events.

While the prospect of a Carrington Event is daunting, awareness and preparedness are key to mitigating its potential impact.

“Although it could happen this afternoon or in 150 years, it is something people should know about, and there should be a plan for it,” Steyn said.

On the topic of whether we are currently at heightened risk of a Carrington-class CME, Steyn said it was difficult to say whether this solar cycle’s maximum had already occurred.

Steyn explained that solar maximum is something that can only be defined in hindsight.

While it is possible that the most severe CMEs of the current cycle may be behind us, its strongest storms may also be yet to come.