Sunspots are the main sources for solar flares ? brief pulses of intense radiation created when the Sun?s magnetic loops spontaneously snap and rearrange themselves. Sometimes, a spate of solar flares will spur an even more violent phenomenon, a billion-ton belch of magnetized plasma that explodes out from our star at millions of miles per hour, plowing into anything in its path. Scientists call these solar belches "coronal mass ejections," or CMEs.
By October 28, the Sun?s rotation had brought the sunspot region into direct alignment with Earth. And then it happened. Around 7 am Eastern time, the region released a pulse of high-energy photons in one of the strongest solar flares ever recorded. Eight minutes later, satellites detected the photons arriving at Earth, followed some minutes later by a shower of slower-moving, high-energy subatomic particles. The particles accumulated in the Earth?s upper atmosphere, where they dramatically interfered with high-frequency radio communications and slightly increased radiation exposures for airplane crews and passengers. At a fuel cost of several tens of thousands of dollars per flight, commercial airlines began rerouting many of their planes on longer, safer routes that did not take them near the Earth?s polar regions, where our planet?s magnetic field caused most of the particles to linger. The flurry of particles also degraded GPS satellite signals, causing ground-based receivers to temporarily lose service or receive flawed navigation data.
As disruptive as the particle shower was, it was only the beginning. At 7:30 am, just after sunrise on the east coast of the United States, a satellite stationed directly between the Sun and the Earth observed our star gain an ominous glowing halo, the telltale sign of a CME aimed directly at our planet. All along the eastern seaboard, millions of people awoke to a seemingly normal, sunny day, unaware that they and our entire planet lay directly in the path of a vicious solar storm.
Shortly after 2 am Eastern time on October 29, the CME arrived at Earth, and the storm?s major effects began. A magnetized plasma front slammed into our planet?s magnetic field, pumping it full of energy to create a "geomagnetic storm" that sent powerful electric currents reverberating in and around the Earth. Vivid displays of auroral lights, normally restricted to higher latitudes, painted the night sky red and green in Florida and Australia.
A geomagnetic storm produces dangerous electrical currents in a manner analogous to a moving bar magnet raising currents in a coil of wire. When a CME hits the Earth?s magnetic field and sends it oscillating, those undulating magnetic fields raise currents in conductive material within and on the Earth itself. The currents that ripple through our planet can easily enter transformers that serve as nodes in regional, national, and global power grids. They can also seep into and corrode the steel in lengthy stretches of oil and gas pipeline.
On October 29, power grids around the world felt the strain from the geomagnetic currents. In North America, utility companies scaled back electricity generation to protect the grid. In Sweden, a fraction of a CME-induced electric current overloaded a high-voltage transformer, and blacked out the city of Malmo for almost an hour. The CME dumped an even larger mass of energetic particles into Earth?s upper atmosphere and orbital environment, where satellites began to fail because of cascading electronics glitches and anomalies. Most were recovered, but not all. Astronauts in low-Earth orbit inside the International Space Station retreated to the Station?s shielded core to wait out the space-weather storm. Even there, the astronauts received elevated doses of radiation, and occasionally saw brief flashes of brilliant white and blue?bursts of secondary radiation caused when a stray particle passed directly through the vitreous humor of the astronauts? eyes at nearly light-speed.
Flares and CMEs from the Sun continued to bombard the Earth until early November of that year, when at last our star?s most active surface regions rotated out of alignment with our planet. No lives were lost, but many hundreds of millions of dollars in damages had been sustained.
The event, now known as the Halloween Storm of 2003, deeply worried John Kappenman, an engineer and expert in geomagnetic storm effects. The Sun had fired a clear warning shot. Its activity roughly follows an 11-year cycle, and severe space weather tends to cluster around each cycle?s peak. The Sun?s next activity peak is expected to occur this year or next, and the chance of more disruptive geomagnetic storms will consequently increase.
Kappenman was particularly frightened by the blackout in Malmo. Subsequent investigations of the CME revealed that it had only struck a glancing blow ? its magnetic field was aligned so that much of the potential impact was dampened, rather than enhanced, by the Earth?s own. If, by chance, the alignment had been different, and our planet had absorbed the full brunt of the CME, who knew how large the blackout would have been, or how long it would have lasted?
Considering the possibility of a long blackout, stretching over weeks, months, even years, Kappenman suddenly saw a foreboding societal reliance on electricity everywhere he looked. Perishable foods and medicines would spoil or freeze in warehouses suddenly stripped of climate control. Municipal stores of fuel and potable water relying on electric pumps would be rendered all but inaccessible. Telecommunications would crash, preventing the general dissemination of information and large-scale coordination between emergency responders. The twin specters of social collapse and mass starvation would stalk entire continents.
"If you lose electricity, within a matter of days you essentially lose almost everything else," Kappenman says. "After the initial blackout, we wouldn?t really understand the seriousness of the situation until several days went by without having things restored. We?d rapidly lose the ability to provide the necessities for modern society."
All this may seem like doomsaying, but the historic record suggests otherwise: The Halloween Storm, in fact, pales in comparison to several earlier events. In 1989, ground currents from a less intense geomagnetic storm knocked out a high-voltage transformer at a hydroelectric power plant Quebec, plunging the Canadian province into a prolonged 9-hour blackout on an icy winter night. A far more extreme geomagnetic storm washed over the Earth in May of 1921, its magnitude illustrated in world-girdling aurorae and in fires that broke out in telegraph offices, telephone stations, and railroad routing terminals ? sites that sucked up geomagnetic currents traveling through nascent power grids. An even more extreme storm in September 1859 caused geomagnetic currents so strong that for days telegraph operators could disconnect their equipment from battery power and send messages solely via the "auroral current" induced in their transmission lines. The 1859 storm is known as the "Carrington Event," after a British astronomer who witnessed an associated solar flare and connected it with the subsequent earthbound disturbances.
"The physics of the Sun and of Earth?s magnetic field have not fundamentally changed, but we have," Kappenman says. "We decided to build the power grids, and we?ve progressively made them more vulnerable as we?ve connected them to every aspect of our lives. Another Carrington Event is going to occur someday." But unlike in 1859, when the telegraph network was the sole technology endangered by space weather, or in 1921, when electrification was in its infancy, today?s vulnerable systems are legion.
Over the past 50 years, global power-grid infrastructure has grown by about a factor of ten. That growth has been accompanied by a shift to higher operating voltages, which increase the efficiency of electricity transmission but make the grid less resistant to exterior impinging currents. As the grid has grown, so too has the practice of importing and exporting electricity between regions, across interstate and international lines. The electricity to power a street light in upstate New York may sometimes come from a hydroelectric plant in Quebec; a neon sign outside a nightclub in Tijuana sometimes gets its juice from a natural-gas power plant in Southern California. This interdependency of nodes in the grid means a power outage in one region can more easily cascade into others, increasing the risk of widespread collapse. We have created a continent-sized antennae?one exquisitely tuned to soak up ground currents caused by space weather, yet poorly equipped to counter their negative influence.
Kappenman has made a career of understanding how a geomagnetic storm as powerful as 1859?s Carrington Event could affect modern infrastructures, and has undertaken a series of studies on the topic underwritten by various branches of the U.S. federal government. He has consistently found that in a worst-case scenario where a great geomagnetic storm strikes with little forewarning, the excess current in the U.S. power grid could overheat hundreds or thousands of high-voltage transformers, melting crucial components and effectively crippling much of the nation?s generation capacity. Based on current production rates, building replacement transformers would take as long as 4 to 10 years, during which more than a hundred million people would be without centrally provided power, causing an estimated economic impact in the U.S. of $1 to $2 trillion in the first year alone.
In direct response to Kappenman?s work, last year the Department of Homeland Security asked an independent group of elite scientists, the JASON Defense Advisory Panel, to investigate his claims. In their report, issued in November 2011, the JASONs expressed skepticism that Kappenman?s worst-case scenario could occur, pointing out that his analyses used proprietary techniques that prevented their full vetting and replication by other researchers. Nonetheless, they sided with Kappenman in stating that in its current form, the U.S. power grid was vulnerable to severe damage from space weather. Like Kappenman, the JASONs called for more space-weather safeguards, recommending that the U.S. grid be hardened against geomagnetic currents and that the nation?s aging network of sun-observing satellites be bolstered.
Not everyone is optimistic that our modern society will successfully address the problem?including physicist Avi Schnurr, who is also the president of the Electric Infrastructure Security Council, a non-governmental organization advocating space-weather resilience. "If a Carrington Event happened right now it probably wouldn?t be a wake-up alarm?it would be a goodnight call," he says. "This is a case where we have to do something that is not often successfully achieved by governments, and certainly not by democracies: We have to take concerted action against a predicted threatening event without having actually experienced the event itself in modern times."
Protecting the power grid on Earth is, in principle, relatively straightforward. (Countries such as Finland and Canada have already begun to take action, with promising results.) Most high-voltage transformers are directly connected to the ground to neutralize power surges from lightning strikes and other transient phenomena. They?re vulnerable to space weather because geomagnetic currents flow upward through these ground connections.
By placing arrays of electrical resistors or capacitors as intermediaries between the ground and critical transformers, like those serving nuclear power plants and major metropolitan areas, that connection would be severed?and the space-weather threat greatly reduced if not entirely eliminated. Experts estimate this could be accomplished within a few years, at a cost of hundreds of thousands of dollars per transformer. In practice, however, it?s not so easy. So far, U.S. power companies have balked at voluntary installation of such devices, and current government regulations don?t require such protections.
In 2010, the U.S. House of Representatives unanimously passed the GRID Act, which would grant the federal government authority to take action to protect the national power grid in the event of an emergency, but the bill floundered in the Senate. Undaunted, in February of 2011 Congressional proponents introduced a new, nearly identical bill, the SHIELD Act, which as of this writing has still not come to a floor vote in the House or the Senate. The North American Electric Reliability Corporation, a self-regulatory body for North American electric utilities, formed a Geomagnetic Disturbance Task Force in 2010 to craft new standards and regulations to protect the grid from cataclysmic space-weather-induced failures, but the Task Force?s reports are still forthcoming.
"The real danger here isn?t astrophysical, it?s institutional. The threat to everyone belongs to no one," says Peter Pry, a former official in the Central Intelligence Agency and the U.S. House Armed Services Committee who has tried to spur legislative action on the threat of space weather. After watching year after year in frustration as bills mandating protection of the grid repeatedly floundered in Congress, Pry helped form EMPACT America, a non-profit group chartered to raise public and governmental awareness of electromagnetic threats to the nation?s infrastructure. Pry currently serves as EMPACT?s president, and says the group is devoted to "ramrodding" the necessary legislation through Congress.
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