The far-fetched can quickly become reality, as Covid has shown. Now, scientists worry we are unprepared for a geomagnetic catastrophe.
If you had taken an evening stroll through Manhattan on August 29, 1859, you might have thought the night sky had burst into flames.
That night, across North America, a magnificent display of auroral green illuminated the houses, streets, and farms, before settling into a livid blaze of blood-red. In Boston, San Francisco, and Chicago, crowds of amazed sky-gazers wandered the streets at midnight. In New Orleans, sparks fell from the sky, like rain. Gold miners in the Rockies began to cook breakfast, because they thought it was morning.
"Streamers of yellow and orange shot up and met and crossed each other," wrote one New York Times reporter, "rapidly changing [the sky's] hue from red to orange, orange to yellow, and yellow to white, and back in the same order to brilliant red."
Telegraph communications failed across the world, as poles burst into flames. Some thought it was a gift from God; others thought it signalled the world's imminent demise. Most looked for a scientific explanation, but were left stumped.
In fact, a billion tons of plasma had been beamed away from the sun in just a few hours, creating intense patches of light on the sun's surface, which were spotted through a telescope by English astronomer Richard Carrington from the Kew Observatory in west London. The Carrington event, as it was later named, helped introduce scientists to the concept of "space weather": sun-driven geomagnetic activity just outside the Earth's atmosphere.
It unlocked a fascinating new scientific frontier, but also signalled a new threat to our way of life. And if one particular former Downing St aide is to be believed, Britain is woefully unprepared for a similar space weather event, were it to strike tomorrow. Last Wednesday, addressing Parliament's science committee, Dominic Cummings generated headlines with his blistering attack on the Government's pandemic preparedness. Then, about two hours in, he made a rather worrying aside, mentioning that Whitehall's plan for solar flares, a form of space weather, is "completely hopeless — if that happens we're going to be in a worse situation than Covid".
If the past 14 months have done anything, they have focused our minds on the fragility of our existence. We now know that the far-fetched can quickly become reality; the plot of a Hollywood film like Contagion, once considered a work of speculative fiction, can move into the realm of the mundane.
"Covid has been a wake up call," says Lord Martin Rees, Astronomer Royal, and founder of Cambridge University's Centre for the Study of Existential Risk. "It's made people more aware the unfamiliar is not the same as the improbable, to quote [US elections guru] Nate Silver."
Last month, scientists at Cornell University suggested that major solar storms are once-in-a-century events. Given the last was in 1921, we can expect one to hit some time this century.
We tend to think of the sun as a solid ball of heat, burning steadily. In fact, it is more like a boiling pan, constantly emitting a stream of vapour made up of gas, radiation, and magnetic activity. Normally this "sun vapour" moves happily around the solar system. Humans, protected by the Earth's magnetic field, don't notice, except at the North and South poles, where disturbances in the magnetosphere allow us to see wondrous green auroras in the night sky.
Astronauts get an even clearer view. Chris Hadfield, who spent four months aboard the International Space Station in 2012 and 2013, remembers seeing occasional "flashes of light" when he closed his eyes; and at one point space-walked directly through the southern lights.
But every now and again, thanks to storms of magnetic activity within the sun, our star spits out a larger than normal amount of material. The most common of these events are known as solar flares: intense bursts of ultraviolet radiation that can disrupt radio communications when directed towards Earth. Rarer, but far more serious, are coronal mass ejections, in which part of the sun's atmosphere blasts away, taking one to four days to reach Earth. It was one of these events that fried global telegraph lines in 1859.
Space weather has affected the Earth for millennia. In 1582, "fiery flames" were recorded as having dazzled the skies over Europe and Asia. "At midnight, great fire rays arose above the castle which were dreadful and fearful," wrote author Pero Ruiz Soares, an eyewitness from Lisbon.
But our modern dependence on technology means a similar event would be much more impactful today. According to a 2015 UK Government report, a Carrington-scale space storm could destroy global satellite signals and GPS navigation, plunging us into a communications deadzone, with no phone, radio, TV or internet. Power grids could burn, causing blackouts lasting a year in parts of the world.
After the (relatively minor) Halloween flares of 2003, planes in the UK lost GPS function for a day; passengers on polar flights (such as Dubai to Los Angeles) may have been exposed to 70 per cent of their recommended annual radiation limit in one go. The damage would cost trillions. And we've already seen it happen on a miniature scale: a small solar storm in 1989 triggered nine-hour blackouts across Quebec, Canada.
In his dark call-to-arms, Apocalypse How?, published last year, former UK Tory cabinet minister Sir Oliver Letwin argues we have become increasingly reliant on a global network of energy and communications.
These technologies provide "huge insurance" against some types of threat, like floods and famines; but magnify other threats, such as space weather: "[We should not] assume that all is well because someone, somewhere, is 'dealing with the problem'," he writes. "There are structural issues why such issues and risks don't rise to the top of political agenda, until and unless a disaster materialises."
Also at play is the deeply human desire to avoid thinking about anything too unpleasant or far-fetched. "[Disasters] that are extremely severe but rather improbable — they're the ones it's easy to overlook," says Lord Rees.
But prepare we must, he says.
The threat of a pandemic was top of the global risk list long before December 2019, when doctors in Wuhan first reported the outbreak of a "Sars-like pneumonia". Virologists even pinpointed that "Disease X" would probably come from a bat in Asia. And still, much of the Western hemisphere was caught off guard.
Space weather is much less predictable. Governments may want to up their game to prevent catastrophe the next time the skies turn green.