Predicting the end of the world is both a
sure bet and a fool's errand. Eventually, the total destruction of
civilization, 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 Dec. 21, 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
American 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 to the huge
creatures on display nearby. But one thin, grayish-beige layer might
explain what exterminated these great beasts: It's the impact residue of
a 6-mile-wide asteroid that struck the Yucatán 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. Twenty-two hundred miles west, in
Yellowstone National Park, one of America's most popular tourist
attractions, is another ominous harbinger of destruction. About once
every hour, the pool around the Old Faithful geyser explodes in a
fountain of spray 145 feet 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 miles. 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 percent of all sea life.
In the cruelest 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 Center recently synthesized 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 synthesizing a new organism goes down
every year," says Dr. Ali Khan, head of the Office of Public Health
Preparedness and Response at the Centers 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
eons like the alligator and the coelacanth. "The safe bet is that we
won't make it, because 99.9 percent of things don't," says Timothy
Spahr, director of the Minor Planet Center in Cambridge, Mass., an
asteroid- and comet-tracking organization.
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.
