But not by everyone. As Keller has steadily accumulated evidence to undermine the asteroid hypothesis, the animosity between her and the impacters has only intensified. As the five-hour drive to our hotel in rural India turned into 12 after a stop to gather rock samples, Keller aired a long list of grievances. She said impacters had warned some of her collaborators not to work with her, even contacting their supervisors in order to pressure them to sever ties. Thierry Adatte and Wolfgang Stinnesbeck, who have worked with Keller for years, confirmed this. Keller planned to spend a week gathering rocks in two different regions of India, beginning with the area around Basar, a dusty village of 5, in the center of the country.
Our days in the field settled into a predictable routine. From about every morning until as late as midnight, we fanned out from the hotel. Our six- or seven-hour drives to distant quarries revealed the rhythms of rural neighborhoods, where women still fetched water from communal pumps and shepherds scrolled on smartphones while grazing their flocks. The geologists were searching for outcrops—areas where erosion, construction, or tectonic activity had exposed the inner layers of rock formations, from which the scientists could decode the history of the landscape.
Most mornings, Thierry Adatte set our course by studying satellite images for signs of quarries big beige rectangles or switchback roads pale zigzags.
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For someone accustomed to thinking about time in multimillion-year increments, Keller grew surprisingly impatient over wasted minutes. The forams, for example, gradually shrank, declined in number, and showed less diversity, until only a handful of species remained—results consistent with what many paleontologists have observed for animals on land during the same time. More problematic still, Chicxulub did not appear to Keller to have been particularly deadly.
And then there was the issue of the four previous mass extinctions. None appeared to have been triggered by an impact, although numerous other asteroids have pummeled our planet over the millennia. Pro-impact scientists counter that not only was the Chicxulub asteroid gigantic, it also landed in the deadliest possible site : in shallow waters, where it kicked up climate-altering vaporized rock. They reasoned that the two must be synchronous, because the destruction caused by the asteroid would have been near-instantaneous.
This looked like circular logic to Keller, who in set out to investigate whether the two really were concurrent. This was evidence that thousands of years had elapsed in between, she argued. Based on similar results from Haiti, Texas, and elsewhere in Mexico, Keller concluded that the asteroid had hit , years before the extinction—far too early to have caused it. So what did cause it? Keller began searching for other possible culprits. She was looking for a menace that had become gradually more deadly over hundreds of thousands of years, such that it would have caused increasing stress followed by a final, dramatic obliteration.
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The fifth extinction, the one that doomed the dinosaurs, occurred just as one of the largest volcanoes in history seethed in the Deccan Traps. On this excursion, Keller hoped to gather samples that would allow her to create a detailed timeline of Deccan activity in the , years leading up to the extinction.
The goal: to see whether its biggest belches correlated with environmental stress and mass dying around the world. Basar was miles east of some of the highest points in the Deccan Traps, an area near the epicenter of the eruptions. Keller had chosen Basar because she suspected that the long, low stretches of basalt around us had been formed by some of the largest lava flows—ejected during major eruptions immediately preceding the extinction.
To prove that, however, Keller needed to have the rock dated. We were snaking down a sinewy road one afternoon when Adatte hollered, the van screeched to a stop, and everyone scrambled out to inspect a steep hill in the elbow of a hairpin turn. Rising up from the asphalt were several yards of pebbly, khaki-colored rock, then a thin band of seafoam-green rock, followed by a pinkish layer, and then round, brown rocks interspersed with white roots.
Adatte sank to his knees and burrowed into the pebbles. Eddy licked a rock, to determine whether it was clay. Keller sprinted up the incline until she was eye level with the greenish layer.
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She translated the outcrop for me as though it were text in a foreign language. Rocks record the passage of time vertically: The distance between where Adatte sat covered in gravel and where Keller perched at the top of the hill potentially represented the progression of several hundred thousand years. She passed me a chunk of the seafoam-colored rock and pointed to a tiny white fossil protruding like a baby tooth: evidence of tempestites, broken shells carried in by a storm.
The pinkish soil above that had been buried under lava—the brown rocks covered with tangled roots.
Since the pinkish layer and the shells predated the flows, they could help pinpoint that particular eruption. Geology is a field of delayed gratification, and there was little else the scientists could say definitively before getting the samples into a lab. While Syed Khadri fielded questions from puzzled locals who wanted to know why the foreigners were playing in the dirt, Keller, Adatte, and Eddy filled clear-plastic bags with fistfuls of rock to ship home.
Back in the van, Adatte told me about a recent conference where several researchers had debated the validity of Deccan volcanism versus the impact theory in front of an audience of their peers, who had then voted, by a show of hands, on which they thought had caused the extinction.
Adatte said the result was 70—30 in favor of volcanism. Our long stretches in the car provided Keller ample time to continue inventorying her own numerous brushes with extinction. Her childhood could pass for the opening of a Brothers Grimm fairy tale. According to stories Keller heard as a kid, their fortune from hotels and real estate kept the children wearing Parisian couture and summering in Austria. The young couple took out loans to buy a farm, where they raised cows, sheep, ducks, rabbits, vegetables, and their 12 children, the sixth of whom was Keller.
Keller grew up among rocks, in the alpine crevices of a Swiss village where the neighbors still believed in witches. Then, much as now, she considered herself in a league apart from her peers.
At age 12, Keller wanted to become a doctor. Her teacher, concerned by these delusions of grandeur, called in a Jungian psychologist to administer a Rorschach test and remind Keller that the daughter of such a poor family should aspire to less. Two years later, Keller—given the choice of becoming a maid, a salesgirl, or a seamstress—apprenticed with a dressmaker. Her mother hoped that she would help clothe her siblings. In her teens, Keller resolved to die before she turned She tried to kill herself by taking sleeping pills, failed, then figured she would live as dangerously as possible and die in the process.
In , at age 19, Keller quit her job in Zurich and hitchhiked through Spain and North Africa for six months.
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She continued her trek around the globe: Greece, Israel, Czechoslovakia, and Austria, where her plan to continue on to Russia was interrupted when her health failed. It was hepatitis, which she had contracted at the Algerian border. After a year of recovery, Keller set sail from Genoa to Australia, which she planned to use as a jumping-off point for travel throughout Asia. Keller recalls that during the three-week journey, her ship collided with its sister vessel, hit a typhoon in the Indian Ocean, and was found to be infested with mafiosi smuggling weapons.
But Keller spoke better English than the official realized. A priest came to administer last rites and, as Keller hovered in and out of consciousness, commanded her to confess her sins. Twice, she refused. The experience also cured her of her death wish. Keller eventually made her way to Asia, then arrived in California with plans to continue to South America.
Instead, she settled in San Francisco and, at age 24, returned to school.
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She enrolled in community college, telling the registrar that her academic records had been destroyed in a fire, and later transferred to San Francisco State University, where she majored in anthropology, the most scientific field she could enter without a background in math or science. Her passion for mass extinction began with a geology class she took during her junior year.
She became the first member of her family to graduate from college, and then one of the first women to receive a doctoral degree in earth sciences from Stanford. In , she joined the faculty at Princeton, where she is currently one of two tenured women in the geosciences department.
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Although Keller is alert to situations in which women are treated differently from men, she hesitates to blame sexism for the hostility she has faced. Keller adores her work. Never before have I encountered someone so gleeful about catastrophe. To her, mass extinctions are not depressing. And the only way to find out is really to study the history. Instead, she expressed a dim view of what 44, years of human civilization will leave behind, much less her own few decades on the planet.
A nanosecond in history. Who will find our remains? Laki let loose clouds of sulfur, fluorine, and hydrofluoric acid, blanketing Europe with the stench of rotten eggs. The sun disappeared behind a haze so thick that at noon it was too dark to read. Destruction was immediate.
Acid rain burned through leaves, blistered unprotected skin, and poisoned plants. People and animals developed deformed joints, softened bones, cracked gums, and strange growths on their bodies—all symptoms of fluorine poisoning. The global water cycle is intensifying due to climate change, with wetter regions generally becoming wetter and drier regions becoming even drier. A UN report highlights that at present, an estimated 3. Melting glaciers in both the Andes and the Himalayas threatens the water supplies of hundreds of millions people living downstream. A severe drought in Cape Town in led to severe water restrictions being put in place.
Climate scientists have now calculated that climate change has already made a drought this severity go from a one in year event to being a one in a hundred year event. Sea level is rising faster in recent decades. Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms. Sea level rises will cause inundation of low lying land, islands and coastal cities globally.