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How a Rare Solar ‘Superflare’ Could Cripple Humanity
Our networked, electrified society makes us uniquely vulnerable to the effects of sudden solar weather
Life on Earth wouldn’t be possible without the steady shine of our sun, but every now and again, it flares up, at times so strongly it disrupts cell phone calls, knocks a satellite or two silly, trips a power grid, even in one extreme case, starts fires. But in modern times at least, the sun hasn’t yet erupted in a “superflare” — the kind of colossal cosmic disturbance scientists have detected emanating from sun-like stars elsewhere in the galaxy.
But a new study suggests it could happen here. And the results would be catastrophic.
“Our study shows that superflares are rare events,” says Yuta Notsu, a visiting researcher in the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. “But there is some possibility that we could experience such an event in the next 100 years or so.”
A superflare would be hundreds or even thousands of times stronger than the largest solar flare recorded by modern instruments, Notsu and colleagues note in the Astrophysical Journal. The findings were presented last week at an annual meeting of the American Astronomical Society.
While a superflare would likely be devastating, there is already broad agreement among scientists that a far less powerful solar storm, similar to at least two known to have occurred in recorded history (one that struck Earth, one that missed), would in this era of modern communications cripple technology and potentially even society as a whole.
Proof of concept
Solar storms are common. Here’s how they work:
Sunspots, darker areas of intense magnetic energy on the surface of the sun, behave a bit like a shaken soda bottle, trapping energy until the pressure becomes too much and the cap blows off in an eruption. Instead of a splash of carbonation, a flash of electromagnetic radiation — X-rays and other wavelengths — arrives at the Earth about eight minutes later.
A superflare would be hundreds or even thousands of times stronger than the largest solar flare recorded by modern instruments.
With some eruptions, a related cloud of charged particles, called a coronal mass ejection (CME), billows off the sun, creating a space storm. Think of it as a gargantuan bubble of tangled magnetic fields and billions of tons of superheated gas called plasma.
When a sunspot erupts in the direction of Earth, a CME will reach our planet anywhere from about 18 to 36 hours later.
The Earth itself is a giant magnet, with field lines that fan out from the poles into the atmosphere and beyond. This magnetic field surrounding the planet makes life possible by deflecting the constant, harmful stream of charged particles called the solar wind. The Earth’s magnetic field typically absorbs the blow of a CME as well, bending and twisting in a heavyweight bout of bubbles. But if a CME is particularly powerful, and if the two magnetic fields are aligned in opposite directions, they can connect — just as two child’s magnets do if you turn them the right way . And that’s when sparks fly.
Most CMEs do nothing more than disrupt radio signals and fire up the Northern Lights, colorful auroras that grace the skies above the Arctic Circle. In stronger storms, those curtains of color can even drift as far south as the northern United States.
The strongest solar flares overwhelm Earth’s magnetic field, like a boxer who’s taken too many jabs. In scientific terms, a powerful connection can create a rift, letting in a flurry of electrified punches. This can have serious consequences, inducing currents in anything on the ground that’ll conduct electricity. Like electrical grids.
In 1989, a solar storm hit Earth with such force that it brought our natural planetary protection system to its knees and even created electrical currents underground, delivering a knockout punch to the Hydro-Quebec power grid. Power was cut to the entire Canadian province of Quebec for several hours. A patchwork of U.S. power grids and some utilities also suffered electrical disruptions. The effects were felt on high, too: Some satellites “actually tumbled out of control for several hours,” according to NASA.
But that was nothing compared to what could happen.
The worst solar storm known to pummel Earth in recent history struck on Sept. 2, 1859. Colorful auroras snaked as far south as Hawaii and Cuba. There was no power to go out, so for many people, the event might’ve gone unnoticed. The only “modern” communication that existed was the telegraph — and it didn’t fare well. The force of the solar storm, called the Carrington event for the British astronomer Richard Carrington who made solar observations at the time, was so powerful it shorted out telegraph wires, burned some of the operators, and ignited widespread fires in the United States and Europe.
The effects would be far worse if such a storm hit now. “Today’s even more sensitive electronics and satellites would be devastated should an event of that magnitude occur again,” writes Roger Dube, a research professor at the Rochester Institute of Technology.
“If the eruption had occurred only one week earlier, Earth would have been in the line of fire.”
More recently, a close call frightened the bejesus out of Daniel Baker, a University of Colorado researcher who studies space weather.
In July 2012, the sun kicked up what Baker estimates was the most powerful storm since the 1859 Carrington event. But the sunspot it emanated from was not aimed our way, so while the storm shot out across Earth’s orbit at some of the fastest CME speeds ever seen — 1,800 to 2,200 miles per second — it missed our planet entirely. Here’s what it looked like to NASA’s STEREO-A satellite:
The event was well documented by satellites, and Baker and colleagues detailed its power in the journal Space Weather. “Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did,” Baker said in a statement at the time. “If the eruption had occurred only one week earlier, Earth would have been in the line of fire.”
Today, Baker oversees the lab where Yuta Notsu is currently a visiting scientist, but he was not involved in Notsu’s study. Baker notes that Notsu’s analysis of Kepler data on sun-like stars is “very important and valid,” and he says the possibility of a superflare — something much more powerful than the 2012 event — “should be taken seriously.”
The 2012 near-miss and the 1859 direct hit involved solar eruptions “only” five to 10 times more powerful than the March 1989 storm that knocked out Canadian power, Baker points out — nothing like Notsu’s prediction of a monster hundreds to thousands of times more powerful.
If the 2012 space storm had struck Earth, it would have produced “immensely dangerous effects in our modern power, communication, and navigation systems” and “we might still be picking up the pieces today,” Baker says in an email. “If an event were to occur that was yet another factor of 10 or 100 stronger in key respects compared to the 2012 event, I think the effects on modern space- and ground-based technological systems could be quite devastating.”
A 2008 report from experts commissioned by the National Academy of Sciences warned that if a flare similar to the 1859 tempest were to occur today, it could cripple communications, cause up to $2 trillion in damage (in 2008 dollars) in just the first year, and lead to long-lasting social disruption. Hurricane Katrina in 2005, the most expensive natural disaster in U.S. history, caused a mere $166 billion in damages in current dollars.
The National Academy report discusses how power lines act like antennas for the electrical energy released in a solar storm. Copper windings in large, expensive transformers — vital notes in an electrical grid — can melt. And when a transformer goes, there can be a cascade effect, crossing from one connected power grid to the next. Referencing a 1921 solar storm that struck Earth and is thought to have generated ground currents 10 times stronger than the 1989 Quebec event, the report explains how hundreds of failing transformers across the United States could leave 130 million people without power.
The lights would go out, but that would just be the beginning. Cell phones need to be charged. Cell towers require electricity. Gas stations and water treatment plants don’t work without power. A repeat of the 1859 Carrington event would lead to “extensive social and economic disruptions,” the report warned. Consider all the interdependent technologies, services and agencies that would be disrupted:
Water distribution would be affected “within several hours,” the report stated. “Perishable foods and medications lost in 12–24 hours; loss of heating/air conditioning, sewage disposal, phone service, fuel re-supply and so on.” Replacing transformers could take weeks or months, the experts wrote. Manufacturing plants that might make all the newly needed transformers could be out of power. It might take four to 10 years to recover.
“It really looks like another 1859 event could be pretty devastating today,” says Justin Kasper, a University of Michigan scientist who studies the sun and the impacts of space weather on society. “Without electricity, communications, there is a cascade effect that could lead to a major disaster. Imagine no food, electricity or communications in half the country for months.”
Another concern experts have is the sun’s ability to throw a powerful one-two electromagnetic punch, hitting a planet when it’s down. In fact, on rare occasions, activity ramps up and multiple sunspots fire in rapid succession. In the fall of 2003, the sun unleashed at least nine major flares inside two weeks.
Notsu’s team is not the first to consider the possibility of a superflare. But their new study is the most comprehensive done yet.
They sifted through information from NASA’s planet-hunting Kepler Space Telescope, identifying stars that had flared in the past. They then used data from the European Space Agency’s Gaia spacecraft and from the Apache Point Observatory in New Mexico to take a closer look at 43 of the flaring stars that resemble our sun. No surprise, they found that hot young stars — like people — are more prone to outbursts. The surprise: Older stars, similar in age and other characteristics to our 4.6-billion-year-old sun, continue to flare up in super ways, albeit less frequently.
“Young stars have superflares once every week or so,” Notsu says. “For the sun, it’s once every few thousand years on average.”
The team also cites events back here on Earth, from the years 774 and 993, when signatures of solar storms, in the form of radioactive carbon-14, became embedded in tree rings, according to other studies. It’s not known exactly how powerful those blasts were, but they were definitely more powerful than the 1859 event, Notsu says in an email.
“If a superflare occurred 1,000 years ago, it was probably no big problem,” he says. “People may have seen a large aurora. Now, it’s a much bigger problem because of our electronics.”
Kasper, the University of Michigan researcher, was not involved in Notsu’s research, but he calls the superflare scenario plausible. Kasper points out, however, that satellites have been able to observe solar storms for only a short period of time, especially compared to the vast age of the galaxy. “It is very difficult to estimate the probability of the worst-case event when you only have 50 years of observations from space.” And he adds: “The major problem in translating this is we don’t know if a superflare will also produce a super coronal mass ejection.”
The sun sometimes generates powerful flares (the radiation that arrives in 8 minutes) that aren’t accompanied by a CME. Little to nothing is known about any possible relationship between other stars’ superflares and CMEs. In fact, it was only last month that the first study was published regarding a CME observed in any detail on another star.
It’s worth noting that a solar superflare alone, sans any CME, would still cause serious problems to the planet.
“The superflare itself would probably at least temporarily dazzle many of our spacecraft,” Kasper says. “It would be lousy if you were an exposed astronaut.” In 1972, in between the Apollo 16 and 17 missions, there was a large flare that would have almost surely sickened any astronauts in space, due to the radiation exposure, and might even have been deadly, Kasper says. It seems reasonable, he figures, that a solar flare 1,000 times stronger than any we’ve recorded would deliver even more radiation.
The extra energy from a solar flare also causes layers of atmosphere to swell outward. Satellites in low-Earth orbit (LEO), such as the International Space Station and many communications satellites, are in very thin air, but there are atmospheric molecules up there, causing drag. (The Space Station periodically fires boosters to lift it back into position.) During a flare, denser layers of the atmosphere move higher, adding to the slight drag.
“Our uppermost atmosphere would swell up from all the X-rays and UV [radiation], and the drag on spacecraft would jump for a couple days,” he explains. “You’d probably lose a lot of spacecraft in low-Earth orbit.”
Are we prepared?
In recent years, our sun has been pretty quiet. It is expected to reach a low ebb in its roughly 11-year cycle of activity later this year or early in 2020. Forecasters say activity should ramp up starting in 2020, reaching the next peak between 2023 and 2026.
The good news: Scientists predict the next cycle, Solar Cycle 25, will be moderate, as was this one. And new research, led by Irina Kitiashvili at NASA’s Ames Research Center, indicates that the number of sunspots — a measure of solar activity — might be 30 to 50% lower than during the last peak.
The bad news: Sunspots are unpredictable and can show up even during low points in the cycle, and the next big flare, super or otherwise, could come at any time. “The trillion-dollar question is, ‘What are the odds?’” says Kasper, who testified on the threat earlier this year before the Senate Committee on Homeland Security and Governmental Affairs.
Kasper told Congress that to prepare ourselves for the next bout of space weather, we must first improve surveillance. “We need spacecraft closer to the sun providing earlier warning of Earth-directed events and their properties, better models of these eruptions and regional forecasts of geomagnetic disturbances,” he testified. “Most importantly, we need leadership with a mandate to coordinate and direct the research and operational components of space weather that are spread over multiple agencies.”
A superflare would vindicate the doomsday preppers.
“Politicians in D.C. are well aware of this threat,” Kasper tells me now, “but they need at least an estimate and not a complete guess of the probability and impact so they can determine the level of investment in safeguards.”
For now, though, the U.S. power grid is sitting duck. Longer wires, if they can’t be disconnected when a storm approaches, create greater opportunities for damage, as the telegraph wires showed so dramatically back in 1859. “The only way to reduce vulnerability to geomagnetic storms is to substantially revamp the power grid,” says Dube, the Rochester Institute of Technology researcher. “Now, it is a vast web of wires that effectively spans continents.”
Otherwise, a superflare would vindicate the doomsday preppers — at least those who’ve gone solar.
“A family using solar panels and batteries for storage and an electric car to get around would likely find its water supply, natural gas or internet service disrupted,” Dube says. “But their freedom to travel, and to use electric lights to work after dark, would provide a much better chance at survival.”