Fear is an ancient emotion. The same fight-or-flight response that gripped cavemen stalked by a hungry saber-toothed tiger still grips modern humans when they skydive for the first time. Our heart rate increases, blood is redirected to critical body parts, adrenaline spikes, and our strength, stamina and senses are all heightened [source: Taylor]. In other words, we become scared superheroes ready to fight hard or run fast depending on the situation. It's a reaction that's served us well: Scientists credit it as an important part of the survival of our species.
Unfortunately, there have been many terrible events in our history that have struck fear in the hearts of people across the globe. In many of these instances, the danger was imminent and horrifyingly clear, like the sight of a mushroom cloud rising over Hiroshima in 1945 or the tsunami wave rolling toward the beaches of Indonesia in 2004.
Other times, however, the threat was less obvious and fear lay in the dark unknown. Will a natural disaster happen and wipe out your town? Might a serial killer strike your neighborhood and endanger your family? Could an astronomical event impact the Earth and all life on it? Will a regional conflict become global and spark World War III? It's from this angle — a fear of the uncertain — that we compiled our list of 10 anxiety-inducing events in history.
The Y2K bug was big news in December 1999. Dire predictions of accidental missile launches, nuclear meltdown, financial panic and airplanes falling from the sky had people building bunkers and stocking them with Spam. Wilderness-survival boot camps recruited participants like never before. Even the venerated Time magazine set up a generator-powered "war room" in the basement of their building. Despite reassurances from experts, people were worried. So what was this Y2K bug, and why was it turning otherwise normal people into end-of-timers?
Y2K was a computer bug. A completely avoidable computer bug. The whole problem started back in the 1960s when computer programmers, concerned about expense and limitations of digital storage, wrote code that only allowed two digits for the year. So "10/15/1965," for example, would simply be coded as "10/15/65." Everything was fine until the 1990s, when concern grew that computers might interpret the looming year 2000 — known in computer-speak as "00" — as 1900. Calculations for everything from interest rates at banks to safety checks at nuclear power facilities would be incorrect. In preparation, the United States spent millions of dollars updating military, transportation and financial computer systems [source: Rothman]. Still, the problem played on people's lingering fear of technology, and the belief among some Christians that Jesus might return 2,000 years after his birth only escalated the concern [source: Sheesley].
On Dec. 31, 1999, people watched with a little more anxiety and a little less celebration as the clock ticked towards potential Armageddon. Then, at midnight, nothing happened. Aside from a few minor, isolated incidents, everything was fine. Countries that didn't prepare were no worse off than those that did. And everyone breathed a collective sigh of relief [source: National Geographic].
Politics undoubtedly cloud the issue of climate change. But if 97 percent of actively publishing climate scientists, 18 American scientific associations, 200 worldwide scientific organizations, and numerous science academies, U.S. government agencies and intergovernmental bodies are right about human-caused climate change, you should be afraid. Very afraid [source: Shaftel].
Here are the facts. Sea levels have risen 6.7 inches (17 centimeters) over the past century. As of 2016, the 10 warmest years since 1880 have all happened within the past 12 years. Oceans are warming and acidifying. Ice sheets, Arctic sea ice, glaciers and snow cover are all retreating [source: NASA, "Climate Change"]. And the cause of all these changes, atmospheric carbon dioxide, has risen to concentrations that are unprecedented in human history. In 2016 an important measurement station in Tasmania recorded levels exceeding 400 parts per million, which is higher than any time in the past 15 million years [source: Readfearn].
So what's the big deal? Some of the consequences of a warming planet are already happening, including accelerated sea rise, more intense rainfall, more severe heat waves, increased wildfires and decreased water availability. A trend toward stronger and more frequent hurricanes, though not yet definitively tied to climate change, is also expected to accelerate.
Those in vulnerable areas, like the low-lying Pacific island nation of Kiribati, are particularly concerned but determined to fight back. That nation's leader directed a Japanese firm draw up plans for a floating island to sustain part of the country's population and purchased land on nearby Fiji to evacuate the rest [source: Worland]. While such actions may seem crazy now, they could one day prove necessary. Scientists believe climate change will continue to affect the planet through this century and beyond [source: NASA, "The Consequences"].
Sometimes events that happened hundreds of thousands or even millions of years ago are scary, not because tons of people were there to see them, but because they are predictive of what might happen in the future.
Take the Yellowstone supervolcano eruptions, which happened 2.1 million years ago, 1.3 million years ago and 640,000 years ago. The largest of these eruptions was the oldest one, which created a volcanic formation known as the Huckleberry Ridge Tuff. It released a whopping 585 cubic miles (2,450 square kilometers) of molten rock and created a caldera measuring some 60 miles (96.6 kilometers) across. That makes it one of the five largest individual volcanic events in history — nearly 6,000 times larger than the Mt. St. Helens eruption of 1980 [source: Lowenstern et al.].
Yellowstone continues to be an active volcanic zone, as its numerous geysers and hot springs attest. What, then, would happen if there were another such eruption? One of the biggest problems would be the massive amounts of ash thrown into the air, which winds would carry across the United States. The Pacific Northwest and Midwest would be particularly hard hit, resulting in a short-term devastation of agriculture and waterways choked with gray sludge. Such an eruption would also eject large amounts of gasses like sulphur dioxide into the atmosphere, causing a decade-long climate cooling. The resulting changes in rainfall patterns and severe frosts could lead to more widespread crop failure [source: Oskin].
Every decade is defined in part by some quirky event or fad. The 1950s had UFO sightings, the 1970s had Disco Demolition Night and the 1990s had people going into survivalist mode in the months leading up to Y2K. What defines the 2010s? Probably people dressing up as creepy clowns and scaring the pants off of other people.
It all started in August 2016 at an apartment complex in Greenville, South Carolina, where a boy told his mom about a frightening experience: Two clowns tried to lure him into the woods outside their building [source: Teague]. The story was unsubstantiated, but copycats soon emerged. A woman in Alabama created a Facebook page for "Flomo Klown" and threatened to kill people at a local school. Police arrested a man in Kentucky who was dressed like a clown and hiding in a ditch [source: Teague]. In just a few months, people had reported more than 100 clown sightings and threats in the United States, and the phenomenon began to spread to other countries, including England, Canada and Australia [source: Shilling].
The public reaction was frightening as well. People began threatening to shoot clowns, and a mob even formed at Penn State University in response to a clown sighting. All the hysteria prompted author Stephen King — whose murderous clown character Pennywise from his novel It probably contributed to the clown craze — to issue a statement calling for people to cool it [source: Carlson].
All this begs the question: Why clowns? Certainly, popular culture has conditioned us to fear clowns, with fictional portrayals like those in It to actual events like the serial murders committed by John Wayne Gacy, known in the press as "The Killer Clown." But there may be something more fundamental. For one, clowns are unpredictable: You never know if they're going to squirt water on you or pull something from their sleeve. The exaggerated face paint also makes them uncanny — human, but in a strange and mysterious way. We just aren't wired very well to deal with this uncertainty, and the Great Clown Scare is proof [source: Romm].
If you've ever lived in a small town, you know that small sleights or misinterpreted gestures can quickly become a big deal when the local rumor mill kicks into gear. Rural Europe was no different during the late 16th and early 17th centuries. Well, on second thought, there was one big difference: A scorned neighbor in the late Renaissance Europe might accuse you of being a witch.
Take a second to imagine what that would be like. You bring some food over to a neighbor who's just had a baby, and the next day the child comes down with a terrible illness. Or maybe you get upset with someone and make a half-joking quip wishing him harm. You didn't mean it! But before you know it, local officials are dragging you off to a witch trial where logic doesn't matter and torture is the preferred way to draw a confession. Hopefully you can somehow convince the superstitious executioner that you aren't a witch, but if not, you'll be hanged, beheaded or burned at the stake. Yikes!
By the late 1700s, the witch craze was largely over, but not before some 40,000 to 100,000 people had been killed under such outrageous circumstances as those mentioned above. Women — particularly elderly women — bore the brunt of this fanaticism: Eighty percent of those brutally executed in this dark chapter of European history were female. But as the examples above show, these killings weren't some kind of systematic cleansing by the Catholic Church to wipe out pre-Christian religions and the women who perpetuated them. The witch trials, sadly, had more to do with petty, vindictive and superstitious accusers who were empowered by low-level local authorities [source: Miller].
By 1910 the sight of Halley's Comet wasn't a surprise. As early as 1705 astronomer Edmond Halley identified its orbit and predicted its reappearance every 75 to 76 years. He correctly guessed its arrival in 1759, and the comet dazzled the night sky again in 1835. Though telescopes weren't yet strong enough to track its distant progress, everyone expected another sighting in 1910. That wasn't the scary part [source: Weissman].
What stirred everyone into a tizzy was the new discovery that Earth was actually on track to pass through the comet's 15.5-million-mile (25-million-kilometer) tail. Making things worse, a recently-discovered technique known as spectroscopy was used to analyze the composition of the comet, and scientists learned something unsettling — namely that the tail contained a toxic gas known as cyanogen. While most astronomers weren't actually that worried, a nervous public latched on to the claims of people like French astronomer and author Camille Flammarion, who claimed the poison would smother all life on the planet. It was a recipe for mass hysteria.
Churches held prayer vigils, and enterprising con-men sold comet pills to ward off the poison's effects. Even wilder theories emerged suggesting that the comet's gravity might throw off Earth's tides and cause the Pacific to empty itself into the Atlantic. Despite the doomsday predictions, however, nothing happened. Halley's Comet came again in 1986, and with any luck, we'll all see it again in 2061 [source: Clark].
Murder is one of the most heinous acts a person can commit, and unfortunately, it is all too common in our society. Usually, victims know the killer. But in some horrifying cases, murderers choose to kill people at random. That was the terrifying reality during the D.C. sniper attacks of 2002.
On Oct. 2, John Allen Muhammed and Lee Boyd Malvo climbed into a blue Chevrolet Caprice and headed toward an Aspen Hill, Maryland, craft store on a deadly mission. Their first shot shattered the window of the store but narrowly missed the cashier's head. Having failed at their first attempt, the duo moved on to a grocery store where they killed a man walking across the parking lot. The shootings continued for the next three weeks, claiming victims at a gas station, home improvement store, middle school and other ordinary public places [source: Philofsky].
As you can imagine, people were rattled. Kids stayed home from school, sporting events were canceled and people hid while pumping gas. Mercifully, police were able to identify Muhammed and Malvo as suspects and capture them at a rest stop, but not before they killed 10 people and injured three others. Their motives were unclear. Perhaps it was an elaborate plot to cover up the planned murder of Muhammed's ex-wife, or even part of a bigger plan to extort the federal government. Whatever the reason for the spree, it remains one of the scariest examples of serial killing in American history [source: White].
"As I walked out [of the President's Oval Office] I thought I might never live to see another Saturday night" [source: National Security Archive]. Now that's a scary quote no matter who said it and what they were talking about. But when you realize that it was John F. Kennedy's Secretary of Defense, Robert McNamara, taking about a possible nuclear strike against the United States, it's downright terrifying. It just goes to show how close the world came to all-out nuclear war during the 1962 Cuban Missile Crisis.
The issue at hand was the Soviet Union's use of Cuba as a launching pad for nuclear weapons capable of striking the United States. Kennedy had warned Soviet premier Nikita Khrushchev not to do it, so when American spy planes identified missile launch sites on the communist island nation, things got tense. Really tense. On Oct. 22, Kennedy ordered a naval quarantine of Cuba in order to prevent Soviets from delivering any offensive weapons. Negotiations went on for six days while the United States Strategic Air Command, which was responsible for the nation's strategic nuclear strike forces, stood at DEFCON 2, the highest level of readiness ever ordered [source: U.S. Department of State].
Thankfully, cooler heads prevailed, or else none of us might be here. On Oct. 28, Khrushchev agreed to remove the missiles from Cuba in exchange for an American promise not to invade the island, as well as the withdrawal of American missiles from Turkey. The brush with nuclear war was a wakeup call to the rival superpowers, which instituted a direct telephone line between the Kremlin and the White House as a result [source: State Department].
Sometimes one person's scary event can have a ripple effect across a nation. That's exactly what happened on Feb. 20, 1962, when Americans held their collective breath as astronaut John Glenn and the Friendship 7 spacecraft orbited 160 miles (257 kilometers) above Earth at a face-melting 17,500 miles per hour (28,164 kilometers per hour). On the line was national pride and confidence in the country's ability to compete with its Soviet rivals.
At the time of Glenn's feat, the Soviet Union was besting the United States in the Space Race, having already sent the first satellite and person into space. Glenn would be the first American to orbit the Earth, but as he prepared to re-enter the atmosphere, he got some bad news from Mission Control: A sensor detected a problem with the heat shield. Considering this was the only thing standing between him and certain, fiery death, it was a bit concerning. As Glenn descended, he watched burning chunks of spacecraft fly by his window, unsure whether these were pieces of the critical heat shield. Fortunately, they weren't, as the sensor that raised the alarm turned out to be faulty, and Glenn landed in the Atlantic without incident.
So what was the big deal? In the 1960s space technology was viewed as a critical component in the nuclear arms race. If Glenn had failed, a struggling space program would have raised some real questions about the United States' national defense capabilities. But instead, the heroic Glenn set the stage for the ultimate American space victory: Landing a man on the moon [source: National Archives].
Beachgoers, frolicking in the warm waters of Indonesia's Indian coast, look up and see a strange sight on the horizon: A swell of water. But curiosity turns to panic as the swell nears land and amplifies into a 100-foot (30-meter) wave hell-bent on destroying everything in its path.
It all started on Dec. 26, 2004, when a 9.1-magnitude earthquake shook the bottom of the Indian Ocean with the force of 23,000 atomic bombs. The movement of the seafloor thrust a tsunami in all directions, like the ripples of a stone tossed in a pond. By the time the waters receded, nearly 228,000 people in 14 countries were dead, and some communities in hard-hit Indonesia were almost completely wiped off the map [source: Folger].
Just as scary as the tsunami itself is the possibility that a deadly event could happen again — despite the installation of an early detection system in the Indian Ocean. See, the Indonesian island of Sumatra sits right next to a hyperactive fault zone. Even if Sumatran residents are instantly warned, they may only have 30 minutes to evacuate. That's nowhere close to enough time, particularly in large cities where evacuation routes could quickly choke with cars [source: Folger].
The 100-year anniversary of the end of World War I offers up a second chance to learn from our mistakes. HowStuffWorks looks at what we need to know.
Author's Note: 10 Scariest Events in History
From the real (climate change, tsunamis, supervolcanoes) to the perceived (Y2K, creepy clowns, Halley's Comet), scary events are a huge part of our shared human history. In fact, there are so many things we've been scared of over the years that it was hard to narrow down the list. So how do we handle these situations? I'd like to think we respond with thoughtful, positive action, but judging from these events it seems mass hysteria is a more common reaction. Now isn't that a scary thought?
More Great Links
- Carlson, Adam. "Stephen King Urges People to 'Cool the Clown Hysteria' After More Reports and Arrests." People. Oct. 7, 2016. (Oct. 12, 2016) http://people.com/crime/clown-sightings-2016-stephen-king-twitter-reacts/
- Clark, Stuart. "Apocalypse Postponed: How Earth Survived Halley's Comet in 1910." The Guardian. Dec. 20, 2012. (Oct. 13, 2016) https://www.theguardian.com/science/across-the-universe/2012/dec/20/apocalypse-postponed-halley-comet
- Folger, Tim. "Will Indonesia Be Ready for the Next Tsunami?" National Geographic. Dec. 25, 2014. (Oct. 15, 2016) http://news.nationalgeographic.com/news/2014/12/141226-tsunami-indonesia-catastrophe-banda-aceh-warning-science/
- Lowenstern, Jacob B., Robert L. Christiansen, Robert B. Smith, Lisa A. Morgan, and Henry Heasler. "Steam Explosions, Earthquakes, and Volcanic Eruptions — What's in Yellowstone's Future?" U.S. Geological Survey. May 10, 2005. (Oct. 11, 2016) http://pubs.usgs.gov/fs/2005/3024/
- Miller, Laura. "Who Burned the Witches?" Salon. Feb. 1, 2005. (Oct. 12, 2016) http://www.salon.com/2005/02/01/witch_craze/
- NASA. "Climate Change: How Do We Know?" Oct. 5, 2016 (Oct. 10, 2016) http://climate.nasa.gov/evidence/
- NASA. "The Consequences of Climate Change." Oct. 5, 2016. (Oct. 10, 2016) http://climate.nasa.gov/effects/
- National Archives. "Transcript of John Glenn's Official Communication with the Command Center (1962)." (Oct. 15, 2016) http://www.ourdocuments.gov/doc.php/doc_large_image.php?flash=old&doc=93
- National Geographic. "Y2K Bug." Jan. 21, 2011. (Oct. 10, 2016) http://nationalgeographic.org/encyclopedia/Y2K-bug/
- National Security Archive. "Interview with Robert McNamara." Feb. 14, 1999. (Oct. 14, 2016) http://nsarchive.gwu.edu/coldwar/interviews/
- Oskin, Becky. "What Would Happen if Yellowstone's Supervolcano Erupted?" Live Science. May 2, 2016. (Oct. 11, 2016) http://www.livescience.com/20714-yellowstone-supervolcano-eruption.html
- Philofsky, Rachel. "D.C. Sniper Attacks of 2002." Encyclopedia Britannica. May 5, 2016. (Oct. 14, 2016) https://www.britannica.com/topic/Washington-DC-sniper-attacks-of-2002
- Readfearn, Graham. "Carbon Dioxide's 400ppm Milestone Shows Humans Are Rewriting the Planet's History." The Guardian. May 20, 2016. (Oct. 10, 2016) https://www.theguardian.com/environment/planet-oz/2016/may/20/carbon-dioxides-400ppm-milestone-shows-humans-are-re-writing-the-planets-history
- Romm, Cari. "People Fear Clowns for the Same Reason They Fear Uncertainty." New York Magazine. Oct. 18, 2016. (Oct. 21, 2016) http://nymag.com/scienceofus/2016/10/clowns-are-scary-because-people-cant-handle-uncertainty.html
- Rothman, Lily. "Remember Y2K? Here's How We Prepped for the Non-Disaster." Time. Dec. 31, 2014. (Oct. 10, 2016) http://time.com/3645828/y2k-look-back/
- Sheesley, John. "Y2K: The New Year's Disaster That Never Happened." TechRepublic. Jan. 2, 2009. (Oct. 21, 2016) http://www.techrepublic.com/blog/classics-rock/y2k-the-new-years-disaster-that-never-happened/
- Shilling, Erik. "The Definitive Map of America's Creepy Clown Epidemic." Atlas Obscura. October 6, 2016. (Oct. 11, 2016) http://www.atlasobscura.com/articles/the-definitive-map-of-americas-creepy-clown-epidemic
- Taylor, Jim. "Is Our Survival Instinct Failing Us?" Psychology Today. June 12, 2012. (Oct. 10, 2016) https://www.psychologytoday.com/blog/the-power-prime/201206/is-our-survival-instinct-failing-us
- Teague, Matthew. "Clown Sightings: The Day the Craze Began." The Guardian. Oct. 8, 2016. (Oct. 12, 2016) https://www.theguardian.com/culture/2016/oct/05/clown-sightings-south-carolina-alabama
- U.S. Department of State. "The Cuban Missile Crisis, October 1962." 2016. (Oct. 14, 2016) https://history.state.gov/milestones/1961-1968/cuban-missile-crisis
- U.S. Geological Survey. "Steam Explosions, Earthquakes, and Volcanic Eruptions—What's in Yellowstone's Future?" 2005. (Oct. 11, 2016) http://pubs.usgs.gov/fs/2005/3024/
- Weissman, Paul. "Halley's Comet." Encyclopedia Britannica. Nov. 4, 2015. (Oct. 13, 2016) https://www.britannica.com/topic/Halleys-Comet
- White, Josh. "Lee Boyd Malvo, 10 Years After D.C. Area Sniper Shootings: 'I Was a Monster.'" The Washington Post. Sept. 29, 2012. (Oct. 13, 2016) https://www.washingtonpost.com/local/crime/lee-boyd-malvo-10-years-after-dc-area-sniper-shootings-i-was-a-monster/2012/09/29/a1ef1b42-04d8-11e2-8102-ebee9c66e190_story.html
- Worland, Justin. "Meet the President Trying to Save His Island Nation From Climate Change." Time. Oct. 9, 2015. (Oct. 21, 2016) http://time.com/4058851/kiribati-cliamte-change/