OpinionThe next global crisis could come from the sun. We should prepare now.

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Solar flare
Coronal mass ejection
Solar flare
A time-lapse video of the sun captured by ultraviolet satellites, released by NOAA in March.

The sun occasionally emits larger-than-usual bursts of energy, known as solar storms. You’re looking at a video of one of these stormy days, captured in March.

The brightest spots are solar flares — regions that emit bursts of radiation.

The storm also emitted massive clouds of magnetized particles and hot plasma. One of these clouds, called a coronal mass ejection, headed straight toward the Earth.

Fortunately, this ejection wasn’t strong enough to cause problems to people — just northern lights in some areas. But things could be different if a more intense burst comes our way.

For example, a storm can damage the electronic components on satellites. Those orbiting around 22,000 miles from the Earth, including telecommunications and Earth-observing satellites, could be among the first impacted.

A severe solar storm could cause malfunctions on satellites closer to Earth. In extreme cases, they might crash into other objects in space or the atmosphere.

The undersea fiber optic cables that are the backbone of the global internet could also be at risk of outages lasting from a few minutes to several hours.

Finally, an intense solar disturbance would produce a magnetic storm enveloping the Earth — posing a threat to electric power grids.

(For design purpose)

Total blackouts, radios gone haywire, an internet implosion — do these hallmarks of doomsday and disaster movies stand any earthly chance of happening? Turns out, that might be the wrong question. One of the greatest threats to global infrastructure comes from the sun.

When we talk about weather, we generally mean snowfall, high winds or simply a light drizzle. But space has weather, too, and that weather includes storms. The sun is the stormiest spot in the solar system, a big ball of roiling plasma with an erratic rotation. The lines of the sun’s magnetic field are constantly moving. The images below, developed by NASA, show a period of intense solar activity a decade ago. They illustrate how magnetic fields shift:

How the Sun's poles shift

Most of the time, this flux produces regular irregularities, noticeable on Earth only as auroras such as the northern lights. But other times, the tangled lines of this field lurch outward and explode — releasing massive bursts of energy into space.

These explosions can produce what’s known as a solar flare, an eruption of radiation that can interfere with high-frequency radio signals and satellites along the globe’s sunny side. About half the time, these flares are accompanied by “coronal mass ejections.” Flares are basically light, but CMEs are, as solar physicist Ryan French explains, actual “physical stuff”: huge clouds of charged particles that can move at thousands of kilometers per second, expanding as they approach Earth. By inducing excess electricity to course across and through the ground, they can do catastrophic damage to power grids and perhaps even undersea internet cables.

A solar storm making an impact 93 million miles away isn’t theoretical. It has happened, sometimes subtly and sometimes dramatically. Solar flares occur frequently, but generally not with enough force to produce harmful effects on Earth. Scientists can identify three storms in the past 150 years of sufficient magnitude to cause real disruption: one in 1859, one in 1872 and one in 1921. The first of these, widely referred to as the Carrington Event, sent telegraph machines on the fritz worldwide. Some of them sparked; some of them stopped working; some of them sent bizarre messages, unprompted by any human.

Nowadays, there’s much more to worry about. Nearly everything the modern world relies on could fail if disabled by a serious enough solar storm. Phenomena like large solar flares and CMEs are most common during periods of “solar maximum” that occur approximately every 11 years — next up around 2025. The good news is, researchers estimate that storms of sufficient magnitude to cause real havoc occur only once every hundred or so years. The bad news is, we’re probably overdue.

The most important thing to know is that there’s no need to panic. There is, however, a need to prepare.

The scariest thing about solar flares is the short window of time people have to respond to them — the eight minutes or so that it takes anything moving at the speed of light to reach the Earth’s atmosphere from the sun. The most severe “X-class” flares can unleash the same amount of power as 10 billion megatons of TNT, which can disturb our ionosphere and disrupt any process that relies on signals beamed down from space.

Here is how solar storms’ power compares to big terrestrial phenomena:

The power of solar storms

Radios might go offline entirely, rendering it impossible not only to listen to the local NPR station but also to communicate with planes and ships. GPS systems might become inaccurate — no small matter for military operations, or oil and natural gas rigs, that depend on location data being perfectly precise. Other industries that depend on similarly accurate timing data, from finance to media, may also run into trouble.

All this is temporary. But satellites closer to us, in lower Earth orbit, can also suffer more permanently in a rough enough storm. They can drift out of their typical position thanks to drag, after radiation boosts the density of their surrounding atmosphere. That can lead to a collision in orbit, or to satellites crashing down to Earth. That’s what befell 38 of the 49 new satellites in Elon Musk’s Starlink fleet in 2022, and the storm responsible was considered fairly mild.

Coronal mass ejections, in contrast, provide a longer response window: at least half a day, sometimes multiple days. Humans can see them coming, but when they do arrive, they can cause on-the-ground devastation — like the CME that hit the planet in 1989, taking down the entire Quebec power grid and knocking out 6 million people’s electricity for nine hours, interfering with other parts of the North American grid, and causing damage in Europe.

The risk is highest not for electric current traveling locally from a nearby substation to your home, school or office, but for power traveling to those substations from large, central facilities where power is generated. That means a lot of people could suffer a blackout at the same time — and, because the United States is basically separated into three grids, if a large portion of one of those grids gets fried, it will prove difficult for another, functional grid to compensate. No, humans wouldn’t be “sent back to the Stone Age,” as hyperbolists warn. The chips in our smartphones and, indeed, our toasters would be just fine. But the outlets in the walls could go kaput — so good luck charging your ear buds.

CMEs threaten satellites in ways different from mere solar flares, too. Satellites can suffer physical damage from particles, including supercharged “killer electrons,” hurtling directly into key bits of hardware — or zapping a whole machine into dysfunction. One last worry: the undersea cables that allow the internet to travel around the world. There’s at least an outside chance that a CME could cause some of these to break, preventing people from accessing websites that store data globally.

A National Academy of Sciences report estimates that a truly disastrous solar storm could cost as much as $2 trillion during its first year alone. Not only would people have to replace burned-out transformers and other equipment, but every hour of an outage that could last months takes a tremendous toll — by putting the economy, and daily life, on hold.

A catastrophic solar storm is a “low-frequency, high-consequence” event — which means it’s urgent, sure, but very rare. Such phenomena are a lot easier for institutions to ignore than the smaller disasters the planet suffers more regularly. Encouragingly, governments are paying attention.

Scientists can’t predict solar flares, at least not yet. The best they have is probability models, based on foreboding spots that appear on the sun’s surface. Scientists are laboring over artificial intelligence-enabled models that could, someday, improve this guesswork. But scientists can observe flares and notice coronal mass ejections. The United States Geological Survey has observatories monitoring the planet’s magnetic field. Recently, in collaboration with the National Oceanic and Atmospheric Administration, it has been providing real-time maps to utility companies so they can make smart decisions during a storm about where, if necessary, to modulate or cut the flow of power. NOAA and NASA also operate satellites 1 million miles from Earth to monitor the sun — and NOAA’s Deep Space Climate Observatory can alert authorities as much as an hour before a CME that’s likely to affect the grid arrives. Then, people can act.

That means people also have to know what to do. Some steps can be taken ahead of time to protect the grid against any potential hit — as simple as replacing old transformers with newer, more robust ones, or as complicated as placing a sort of force field called a Faraday cage around critical equipment. But this is expensive: The Foundation for Resilient Societies estimates that securing the entire U.S. grid would cost $25.5 billion dollars per year. Officials also need plans for what to do if the grid gets fried anyway. Multiple federal agencies, for instance, are considering a strategic reserve of portable transformers, deployable in an emergency wherever, whenever.

There ought to be the same degree of planning for submarine internet cables, as well as for satellites, potentially in collaboration with international partners, given the global nature of these networks. The United States seems to be serious about this work; the country even has a National Space Weather Strategy. The White House should ensure that these efforts make it off the page and into practice, and Congress should provide funding. Fortifying critical infrastructure would help deal with other types of disasters, too.

Solar storms sound scary, and they are. But for everything to go wrong, everything really has to go wrong: For humans to get stuck in an analog world during the digital age, the GPS has to die, the electricity has to cut out and the internet has to disconnect. The megastorms most dangerous to Earthlings probably won’t do all these things, particularly with the right preparations. But they could still be extremely disruptive. Governments should ready themselves for solar storms as they would for a pandemic: by preparing to prevent disaster in the first place, as well as by building capacity to respond quickly if it strikes anyway.

Everyone else, meanwhile, doesn’t need to stockpile supplies or construct backyard bunkers. In fact, by hiding underground, people would miss out. Stunning auroras could show up in unexpected places, with celestial blues, greens and purples across lower latitudes. With the right preparation, the real worst-case scenario could be a severe storm striking on a cloudy night.

About this story

Sources: NASA, NOAA, TeleGeography.

Special thanks to Dimitris Vassiliadis, NOAA’s Space Weather Follow On project scientist.