Could the world end in 2012? Put aside the goofy prophesies of Mayan calendar doomsayers and join us on a journey into the cold, hard science of civilisation-ending catastrophe.
By Jeff Wise
Pictures by Dan Saelinger
Models by Megan Caponetto
Predicting the end of the world is both a sure bet and a fool’s errand. Eventually, the total destruction of civilisation, the human race, and, indeed, the world is a near certainty. The tricky part about predicting the apocalypse is the timing. But that hasn’t stopped people from forecasting impending doom throughout human history. Holy men, ancient astronomers and even modern computer scientists have all occasionally read the leaves in their occupational cups of tea and concluded that the end is nigh. And, without exception, they have all been wrong. But maybe this year is going to be different. On 21 December 2012, the Mayan calendar will reach the end of a 394-year cycle called a b’ak’tun, which has sent end-time aficionados into a frenzy. (About the movie based on the 2012 theory, the less said the better.) Archaeologists laugh off that doomsday scenario, explaining that the Mayan calendar cycle is no more momentous than our own calendar ticking over from 1999 to 2000. So that’s a relief.
Still, just because the Mayans didn’t predict the end of the world this particular year doesn’t mean our safety is assured. There are plenty of other risks to life on Earth that scientists do take seriously. These might range from disasters that threaten millions or billions of people to an all-out “extinction-level event” that wipes out the majority of life on the planet.
Could one of these global bummers strike us this year? Not likely. But not completely impossible. To understand the infinitesimally small – but nonetheless real – risk of planetary disaster, it helps to travel back in time. Because such events have happened before. And the results weren’t pretty.
To see the evidence, let’s take a trip. Start with a visit to the Museum of Natural History in New York City. On the fourth floor, just inside the entrance to the Hall of Saurischian Dinosaurs, you’ll find a chunk of Montana dirt with dark and light bands layered like Neapolitan ice cream. Not very exciting compared with the huge creatures on display nearby. But one thin, greyish-beige layer might explain what exterminated these great beasts: it’s the impact residue of a 10-kilometre-wide asteroid that struck the Yucatán peninsula 65 million years ago. “In its aftermath we see extinctions of everything from single-celled organisms to the largest dinosaurs,” says Mark Norell, chairman of the museum’s paleontology division. Could another one seal our own fate? Or could some other extraterrestrial catastrophe bring us death from above?
Or maybe it could come from below. About 3 500 kilometres west, in Yellowstone National Park, a popular tourist attraction, is another ominous harbinger of destruction. About once every hour, the pool around the Old Faithful geyser explodes in a fountain of spray 45 metres tall. It’s a cool effect, until you consider what powers it: geothermal energy radiating up from a subterranean plug of magma.
Every 500 000 years or so, the Yellowstone supervolcano erupts and rains lava and ash for hundreds of kilometres. An eruption 250 million years ago in Siberia may have released enough carbon into the atmosphere to cause the largest mass extinction in Earth’s history, the Permian-Triassic, which wiped out 96 per cent of all sea life.
In the cruellest of ironies, the gravest threat to human life on Earth may be other life on Earth – the microbial kind. Let’s turn our tour of all things apocalyptic to the Netherlands, where virologist Ron Fouchier at the Erasmus Medical Centre recently synthesised an airborne version of the H5N1 avian flu. The lethality and frequent mutations of H5N1 make it a serious pandemic threat. The last big influenza pandemic, the Spanish flu of 1918, is estimated to have killed more than five times as many people as World War I. The possibility of a naturally occurring global outbreak is ever present, but the threat from labs is becoming more frightening. “The cost of synthesising a new organism goes down every year,” says Dr Ali Khan, head of the Office of Public Health Preparedness and Response at the Centres for Disease Control and Prevention. “A bad guy could make his own smallpox.”
Although imminent destruction seems all around us, the probability of extinction in any one year is vanishingly small. Our long-term prognosis, however, is far darker. Very few species survive through the aeons like the alligator and the coelacanth.
“The safe bet is that we won’t make it, because 99,9 per cent of things don’t,” says Timothy Spahr, director of the Minor Planet Centre in Cambridge, Massachusetts, an asteroid- and comet-tracking organisation.
We’ve got some time, though. On average, vertebrate species stick around 4 to 6 million years, and modern humans are only about 200 000 years old. And we’re not your typical vertebrates. Our science and technology might ultimately migrate off this little planet altogether. So maybe we’re just getting started.
Space objects strike the earth all the time, but extinction-level impacts occur only once every 100 million years. After the spectacular collision of the Shoemaker-Levy 9 comet with Jupiter (and a host of asteroid-disaster flicks) in the 1990s, Nasa set out to map all large near-Earth objects. But it appears that there are far fewer potential catastrophes in Earth’s neighbourhood than once thought.
A civilisation-killing asteroid would have to be about 1,5 km across, says Spahr of the Minor Planet Centre. (The space rock that ended the dinosaur era is estimated to have been six times that size.) “There just aren’t any asteroids that size out there,” he says.
There is, however, a large population of as-yet-undiscovered objects several hundred metres across. One that we do know about, a 300-metre-wide asteroid called 99942 Apophis, will pass within the orbits of Earth satellites in 2029 and could one day strike the planet. “Worst-case scenario?” Spahr says. “You hit Los Angeles, kill millions of people, and shut down the entire West Coast.”
For a disease to be globally disruptive, it must undergo a flare-up of contagiousness and lethality – like the 1918 influenza pandemic, which in the course of two and half years killed 50 to 80 million people. If the next influenza pandemic is as bad as 1918’s, the equivalent toll would be 210 million. “Knocking off that many people at once would disrupt civilisation,” the CDC’s Khan says. However, he adds that in the past century medical science has developed powerful weapons against disease. “We’re an intelligent species,” he says. “We can fight back.”
But what if that intelligence were turned against us? Thanks to advances in biotechnology, it will become increasingly possible to custom-tailor a pathogen’s lethality. “We’re on the cusp of what could be a very frightening time,” says Charles P Blair, director of the Terrorism Analysis Project at the Federation of American Scientists. “I think in the very near future you’re talking about a potential extinction event.”
The machines take over
Moore’s law – the observation that computer chips get
twice as powerful every two years – implies that, eventually, artificial brains will eclipse the human brain. The big question is, what will the artificial superintelligence of the future choose to do with its gifts?
“The risk is not so much a Terminator scenario, where you get a supercomputer that dislikes humans,” says Anders Sandberg, a researcher and futurist at the Oxford Martin School’s Future of Humanity Institute in England. “A malign neglect would be a bigger problem. You get something that’s very intelligent, but has motivations that are completely non-human. (The computer) might not really care about anything that we care about, but since it’s smarter, it’s going to get what it wants.”
When large stars die, they go out in spectacular fashion.
Having used up their nuclear fuel, their cores collapse inward into a black hole, which then devours the star from inside out. Out of this paroxysm of destruction, powerful beams of energy burst from both poles, shooting gamma rays and charged particles that for a few seconds outshine the rest of the stars in the universe combined.
That’s great for astronomers, who can observe these gamma-ray bursts, or GRBs, from across the universe – but not so good for any planet that happens to be located in the path of the beams. In a one-two punch, a bath of charged particles would quickly kill everything on one side of the planet while intense gamma rays would ionise the atmosphere and cause years of acid rain.
“As a rule of thumb, the danger zone extends to anything within
3 000 light-years,” says Penn State University astronomer Derek Fox, who specialises in gamma-ray bursts. But for us, he says, “it’s not a likely threat”.
The average galaxy experiences a GRB only every 10 million years or so, and the danger zone is a small percentage of that galaxy.
Right now, people are worrying about global warming, but fallout from a nuclear war or a supervolcano could put enough sunlightblocking dust in the air to cause the opposite problem: a deep plunge in surface temperatures. If the Earth stayed cool long enough, a worse catastrophe could ensue.
Back in the ’60s, climate modellers realised that, if the Earth were covered in enough ice, most of the incoming solar radiation would be reflected back into space and the planet would settle into a stable state at about minus 50 degrees. Then, in 1992, CalTech geobiologist Joseph Kirschvink proposed that the Earth had once spent long stretches of time almost entirely frozen over, leaving evidence of glacial deposits in the tropics. Life clung on in a few sanctuaries heated by volcanic springs
Could it happen again? “It’s not something you’d need to worry about next year, or the next 100 years,” Kirschvink says. “Even if the climate became very cold, it would take a long time for glaciers to build up.”
Ten million years after the dinosaurs died, carbon dioxide levels in the atmosphere soared. The oceans absorbed CO2 and became increasingly acidic, triggering a wave of extinction that swept the planet.
Today, carbon dioxide levels are again soaring – but this time, they’re rising 10 times faster. Earth scientist Andy Ridgwell of the University of Bristol in England has modelled the effects of rising CO2 levels and says the damage could be most visible in coral reefs. Not only would reef destruction result in a loss of habitat for an estimated 25 per cent of marine life, it could also expose many coastal cities to greater storm and wave damage. “If (the reefs) vanish, or largely vanish, that will be a real economic, social and environmental catastrophe,” Ridgwell says.
Nevertheless, it doesn’t seem as if acidification is an immediate threat to human life. It would take a severe toll on deep-water species of plankton, but it would largely spare the world’s major commercial fisheries. “A lot of things that are at risk of extinction we might not even notice,” Ridgwell says.
Late last year a big solar storm launched a wave of charged particles through the solar system at 6 million km/h, setting the stage for a display of northern lights that could be seen from well south. But while delightful to the eye, such a storm could some day herald disaster.
The Earth’s magnetic field prevents the Sun’s deadly particles from striking the surface. The motion of those particles, however, can induce strong currents on the ground. During the worst solar storm ever recorded, in 1859, the currents were so intense that telegraph lines burst into flames. “If we had a storm like that today, it would be possibly quite catastrophic,” says Jeffrey Love, a geomagnetic researcher with the US Geological Survey. “Months without electricity could cause losses of trillions of dollars and basically wreck the economy.”
Two millions years ago, a massive volcanic eruption near what is today Yellowstone National Park shot 2 400 cubic kilometres of dust and ash into the atmosphere – 2 400 times more than Mount St Helens did in 1980. If such an eruption happened today, “it would greatly interrupt business as usual around the planet”, says Jake Lowenstern, a geologist with the US Geological Survey and scientist-in-charge at the Yellowstone Volcano Observatory. Aside from the toll in human lives in the vicinity of the eruption, he says, “global air traffic would be interrupted for months, if not years”.
Since that ancient blast, massive eruptions have been taking place every 600 000 years or so – and the last one was 640 000 years ago. On the bright side, the intervals between the Yellowstone supervolcano’s eruptions are extremely erratic. Statistically speaking, it’s very unlikely to blow in 2012, or even within the next millennium.
At present, the magnetic north pole is up near the rotational north pole, but this hasn’t always been the case. Throughout the Earth’s history, the north and south magnetic poles have swapped places, a phenomenon known as geomagnetic reversal. It happens irregularly, every 100 000 to 1 million years, and the last time they flipped was 780 000 years ago. So maybe we’re due. Geophysicist J Marvin Herndon has suggested that the reversal could cause the geomagnetic field to temporarily collapse, disrupting everything from power grids to gas pipelines to communications satellites.
But there’s also no need for immediate panic. Although a flip would occur quickly on a geological time scale, it is far longer in human terms, between 1 000 and 10 000 years. “Whether it’s going to do us harm is an academic question,” says Jeffrey Love, “because it’s not going to happen tomorrow, and it’s not going to happen in our lifetime.”
On 26 September 1983, a satellite-monitoring unit at a secret facility near Moscow received a warning: five nuclear missiles had launched from a base in the US. Luckily, the unit’s officer, Stanislav Yevgrafovich Petrov, was sceptical about the reliability of newly installed equipment, and he chose to wait rather than immediately pass along an alarm that might trigger a nuclear war. His judgment may have saved millions of lives.
Nuclear tensions have subsided considerably since the end of the Cold War. But the threat remains. More countries than ever have the bomb, and terrorist groups and rogue states remain a worry. A study published in 2008 by the journal Physics Today suggests that a regional war involving as few as 100 bombs could cause a nuclear winter, resulting in the lowest temperatures in 1 000 years, whereas an exchange involving thousands of weapons would, the study concluded, “likely eliminate the majority of the human population”.
“Nuclear war is the near-term risk that people tend to forget about,” says Sandberg of Oxford Martin. “If you think historically, we’ve probably been very lucky.”
Artificial black hole
In 1945, a physicist working on the first atomic bomb raised a disturbing possibility: what if the energy released by the fissioning nuclei ignited the atmosphere and wiped out life on Earth? Obviously, that didn’t happen, and mankind survived its entry into the nuclear age.
But the notion that physicists could unwittingly trigger a world-ending catastrophe has not gone away. In 1999, as the Brookhaven National Laboratory prepared to fire up its Relativistic Heavy Ion Collider (RHIC), a Hawaiian man named Walter Wagner filed a lawsuit to have the facility shut down. He claimed that the collision of high-energy subatomic particles could spawn tiny black holes that could subsequently grow until they swallowed the Earth. In more than a decade of operation the RHIC has not produced a black hole, but Wagner is currently warning of the same danger for Europe’s Large Hadron Collider, which is generating yet higher energies.
Mainstream physicists dismiss the threat. “This danger simply does not exist,” says Brookhaven Lab physicist Dmitri Kharzeev. “These energies are high in human terms, but the cosmic rays that naturally occur in space are much more energetic. If high-energy particle collision could produce black holes, one would have swallowed us a long time ago.”
The X Factor
Many of the threats here were inconceivable a century ago. Are there other dangers lurking beyond the fringes of our understanding? Some scientists working on the cutting edge of cosmology have suggested ideas that sound bizarre but one day may be accepted as real.
One is the notion of “vacuum decay”, the idea that space itself might shift to a different quantum state, vaporising everything in it. Another is the theory that structures existing beyond the visible dimensions, called branes, could collide, with equally apocalyptic results.
To astronomer Derek Fox, this kind of thinking is more thought-provoking than disturbing. “Yes, it’s possible that there are things out there in the universe that could be a threat to life on Earth that we don’t know about yet,” Fox says. “But I don’t think these are the things that we need to be most worried about. Every night astronomers are looking into the universe, looking back 10 billion or more years into the past, and they’ve never seen any signs of these sorts of things.”
* Q&A article from Nasa explaining why the world won’t end in 2012