With all due respect to T. S. Eliot, maybe the world really does end with a bang, not a whimper. Whether of our own creation (nuclear holocaust) or of nature’s (asteroid impact), plenty of cataclysms could doom civilization—perhaps even putting the survival of the species in jeopardy. We assessed the likelihood of several doomsday scenarios, from oft-discussed threats such as climate change to more fanciful ideas such as quantum fluctuations that would destroy our universe. The probabilities listed here are not scientific fact—an impossible goal when estimating the possibility of unprecedented events—but informed conjecture based on researchers’ expert opinions. We also relied on those opinions to approximate how catastrophic each event would be, ranging from 1 (localized chaos) to 10 (good-bye, universe).
KILLER PANDEMIC
One in 2 in the next 30 years
Destruction ranking: 4
Humankind is more vulnerable than ever to a devastating, Black Death–style pandemic, says Joseph Fair, director of global field operations for the Global Viral Forecasting Initiative. He declined to predict when one might strike, instead rating civilization as a lowly two on a 10-point preparedness scale. The next pandemic, Fair says, will likely be a pox or a virus that is either new to humans or a more deadly adaptation of a common virus.
SOLAR SUPERSTORM
One in 20 in the next 15 years
Destruction ranking: 2
“We don’t want to be alarmist,” says Daniel N. Baker, a space scientist at the University of Colorado at Boulder, but a solar eruption could grow large enough to knock out the power grids and communication systems over much of the world. “If that were to occur today with our modern, highly electronically connected society,” Baker says, “it would undoubtedly be devastating to the most advanced countries.”
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RUNAWAY GLOBAL WARMING
One in 2 in the next 200 years
Destruction ranking: 3
The ice sheets in Greenland and West Antarctica together contain enough water to raise global sea levels by about 12 meters, erasing coastal cities and making refugees of hundreds of millions of people. Without a change of behavior, humankind could set into motion the irreversible melting of both ice sheets by the end of this century, says Henry Pollack, an emeritus professor of geophysics at the University of Michigan at Ann Arbor and author of A World without Ice (Avery, 2009). “My particular feeling is that it’ll be touch and go as to whether we can actually achieve the avoidance of Greenland and West Antarctic ice loss,” Pollack says. “The consequences of displacing so many people—the world has never dealt with something like that.”
SUPERVOLCANO
One in 100 in the next 1,000 years
Destruction ranking: 5
A supervolcano would spew at least 1,000 cubic kilometers of ash and lava, or about 1,000 times the ejecta from the 1980 eruption of Mount St. Helens. Such an explosion would significantly alter global weather patterns for decades, which would in turn lead to drought and famine.
NUCLEAR WAR
One in 30 in the next 10 years
Destruction ranking: 6
An accident or cyberattack could spur a nuclear exchange between the U.S. and Russia, killing hundreds of millions of people, says Kennette Benedict, executive director and publisher of the Bulletin of the Atomic Scientists. A more likely scenario is a terrorist attack on an urban area using smaller nukes; Benedict pegs those odds at better than 50–50 over the next 15 years.
GIANT ASTEROID IMPACT
One in 1 million in the next 100 years
Destruction ranking: 9
Although a 10-kilometer-wide species ender might be a long shot,
a smaller, more common asteroid strike could still wreak serious havoc. A three-kilometer object (rough odds: one in 200,000 this century) could kill a quarter of the world’s population and temporarily destroy civilization.
NEARBY GAMMA-RAY BURST
One in 15 over 100 million years
Destruction ranking: 7
Most of these cosmic blasts are thought to form when a massive star collapses into a black hole. None has ever been observed in our galaxy, which is fortunate: a nearby flash could pummel Earth with radiation and ravage the atmosphere’s protective ozone layer. Some researchers think that one could have caused a mass extinction 440 million years ago.
BUBBLE NUCLEATION
One in 1 billion in the next 1 trillion years
Destruction ranking: 10
What if another universe popped up spontaneously within our own? This is the bubble scenario, whereby our universe flips into a new state with different fundamental forces. The transition would happen when a tiny bubble pops up imprinted with the new laws of nature, then “expands at nearly the speed of light and engulfs the surrounding space, including what remains of our solar system,” says Alexander Vilenkin, a cosmologist at Tufts University. But we can probably push it way down the worry list. Vilenkin is willing to bet “a large amount of money” that bubble nucleation is not going to happen in the next trillion years. He was not clear on how his opponent would collect were he to lose.
