Government officials, scientific researchers, and media commentators soon speculated about the cause of the flood and about why so many people had died. They pointed to the early and heavy monsoon rains. They railed against poorly built homes, unregulated development along the Mandakini River that runs through Kedarnath, and soil erosion caused by thousands of pilgrims trekking on foot and on donkeys to reach this remote town in the northern Indian state of Uttarakhand. All these factors contributed.<\/p>\n
Yet in the two years since the flood, scientists studying with the care and intensity of forensic investigators have added another key cause: global warming. In recent papers, they conclude that melting glaciers and shifting storm tracks may soon set off more catastrophic floods in mountainous regions of India and adjacent countries. Atmospheric scientists say that in northern India the intense rains that preceded the disaster are extremely rare.<\/p>\n
But they have discovered that an unusual collision of weather systems steered storms over Uttarakhand and locked them in place, pouring rain down for days. Long-term changes in weather patterns are making such collisions more likely, a development that some scientists believe is caused by global warming. Global warming has is also melting glaciers all over the Himalayas, including one perched above Kedarnath. Some researchers say that had the glacier remained healthy, heavy rain alone would not have destabilized a gravel bank that collapsed, releasing a destructive pulse of debris-filled water.<\/p>\n
Sitting on the carpet in his father\u2019s living room, in New Delhi, 200 miles southwest of Kedarnath, Vaibhav Kaul, a young geographer, watched reports of the disaster on TV. He remembers thinking to himself, \u201cthat was exactly the kind of scenario I\u2019d been studying for the year.\u201d He\u2019d recently completed a Masters degree in Environmental Change and Management at Oxford\u00a0University in the United Kingdom. His thesis studied how Himalayan communities could better prepare for catastrophic floods from the lakes above them. He\u2019d briefly considered making Kedarnath the subject of his research.<\/p>\n
A devout Hindu and descended from Kashmiri Pandits \u2014 an elite caste that has produced many of India\u2019s ruling class of scholars, administrators and politicians \u2014 Kaul had made the religious excursion to Kedarnath once before and hiked two hours above the town to Lake Chorabari Tal. But when he later read a report cataloging the Himalayan lakes most likely to flood and endanger communities below, Chorabari Tal was not among those listed as \u201cpotentially dangerous.\u201d He decided to study towns elsewhere in the Himalayas instead. But his instincts proved to be correct.<\/p>\n
Four months after the flood, Kaul set off on a scientific pilgrimage to the disaster site, determined to learn why a town considered relatively safe had flooded. He wore a traditional robe, hanging to below his knees, and the sort of dark wool vest favored by men in Kashmir, the mountainous region of his ancestors.The flood had severed the eight-mile footpath to Kedarnath from the rest of India. Kaul took a bus to Guptkashi, the closest town with public transport, but nearly 25 miles short of Kedarnath. He continued on foot, astonished at the scale of destruction even so far downstream. The flood had passed through Kedarnath and surged down the Mandakini, joined by swollen tributaries, gathering force and debris. Kaul saw bare abutments where bridges had stood and foundationless houses dangling above\u00a0landslide scars. Thirty hydroelectric plants had been damaged or destroyed.<\/p>\n
About four miles shy of Kedarnath, he came to the former site of Rambara, a way station that once had about 100 seasonal shopping stalls and several small hotels. Pilgrims had rested there over sweet, milky tea and fried flatbreads and bought camping supplies and religious trinkets. Kaul saw only an empty shelf of bedrock strewn with boulders. \u201cOne couldn\u2019t imagine there\u2019d been anything there,\u201d he said later.<\/p>\n
Some of of Kedarnath\u2019s steel-reinforced concrete guesthouses and stuccoed fieldstone homes survived better. Still, nearly three quarters of its 259 buildings had been damaged. More than half had been battered and washed away. The flood took most of its victims in Kedarnath, the season\u2019s first pilgrims. \u201cThey were still finding dead people,\u201d Kaul recalled, noting that he had smelled rotting flesh and watched relief workers excavate a severed leg. Kaul climbed steep hills to an overlook about 2,000 feet above the town. The top of a hulking mountain, nearly 23,000 feet tall and crowned by Chorabari glacier, appeared. It blocked the sky at the head of the valley. At an inflection point, where the slope leveled off, a vast tongue of ice stretched out for a mile. Kaul looked for Chorabari Tal. It should have been visible below him, near the tongue\u2019s tip. But there was no lake to be seen.<\/p>\n
Titanic geologic forces had forged Chorabari Tal during the widespread cold spell that lasted from about 1300 to 1870 and is known as the Little Ice Age. The glacier had bulldozed stone into linear piles \u2014 moraines \u2014 jammed between the advancing tongue and the valley\u2019s bedrock rim. The ice had then receded, leaving the lake\u2019s lens-shaped basin, a depression with no outlet. Rain and melted snow filled it every spring and summer. At times, water drained out through the porous moraine, and the water level dropped.<\/p>\n
Now, as Kaul looked down, he saw that the basin was empty. He knew what had occurred: The moraine had ruptured, letting loose the lake\u2019s entire contents in a catastrophic spasm.<\/p>\n
Kaul surveyed the town sprawling in the valley below him. It was built on a bed of gravel shaped like the prow of a ship sailing toward the glacier. Metal roofs sparkled. Unscathed by the flood, the Kedarnath Hindu temple stood at the narrow end of town.<\/p>\n
The shrine, stately, gabled and thick-walled, was built of huge stacked stone blocks. Priests probably constructed it in the 8th or 9th century, on the site of an even older temple, and dedicated it to the Hindu god Lord Shiva the Destroyer.<\/p>\n From his overlook, Kaul saw the boulder that had saved the temple from destruction. Miraculously, the deluge had scooped up this 30-foot-long rock and dropped it, perpendicular to the current, just steps short of the temple, where it had deflected the churning waters around the historic building. Kaul snapped a set of pictures.<\/p>\n A few weeks later, British geographer Dave Petley, at the University of East Anglia, published some of Kaul\u2019s photos on a blog widely read by landslide researchers. These photos proved what Petley and other scientists had suspected from blurry satellite images released by India\u2019s space agency. They showed a V-shaped cut in the natural dike that had dammed Chorabari Tal for centuries. An 18-wheeler could fit through the break in the gravel wall.<\/p>\n Using Kaul\u2019s photos, Petley explained in blog posts the chain of events implied by the breached embankment in the days before the flood. The lake probably had swelled to capacity during the heavy rain and accompanying snowmelt. The weight of all that\u00a0water could have punched through the dike. When the wall broke apart, an immense wave loaded with boulders raced a mile downhill straight for Kedarnath.<\/p>\n Terrified pilgrims and inhabitants had huddled inside any shelter they found. Survivors describe hearing a tremendous boom. The torrent poured into the Mandakini River, already raging above the town with the downpours and snowmelt. Chandi Prasad Tiwari, a shopkeeper, saw a wave crest over a three-story building. \u201cGod, please help us, please help us,\u201d he recalls sobbing. He felt sure he\u2019d die.The Chorabari Tal\u2019s basin is not huge. \u201cJust a puddle,\u201d Kaul says. But it probably released its entire contents, about 100 million gallons, in a quarter of an hour, say scientists at the University of Calcutta. The team estimated that for several minutes the torrent pounded Kedarnath with half the flow of Niagara Falls.<\/p>\n If Chorabari Tal\u2019s 100 million gallons were the explosive blow that hit Kedarnath and its occupants, what set it in motion? Why did the lake basin, intact for hundreds of years, burst now? Researchers have spent the two years since the catastrophe trying to find out. They suspect two factors: the unusually heavy rainfall, and the degraded condition of Chorabari Glacier.<\/p>\n Monsoon rain poured torrentially throughout India the week prior to the flood. Twice as much rain fell in the first two weeks of June, 2013 as had fallen in the same fortnight in any of the prior 60 years. It fell with ferocity in the mountains of Uttarakhand. Just before the storm washed it away on June 16, a rain gauge at Chorabari Tal set up by Indian researchers recorded 13 inches of rainfall in a 24-hour period. Despite scant long-term weather records for the region, studies show that such a downpour was\u00a0rare, and perhaps unprecedented. One\u00a0research paper<\/a>\u00a0calculated that an equally wet month probably occurs less often than once a century.<\/p>\n Indian researchers attribute the abrupt, intense rainstorms that sometimes drench Himalayan states to a type of weather system called a Western Disturbance, in which moisture travels to India on high altitude winds from the Mediterranean Sea, over the Arabian Peninsula, past Iran, Afghanistan, and Pakistan. There the wet wind hits the Himalayas and drops its moisture, showering northern India several times a month during the winter. Western Disturbance storms are less common after mid-spring. Then, the summer monsoon begins, bearing moisture from the Bay of Bengal and spreading north and west from near Kolkata on India\u2019s eastern coast.<\/p>\n In an interview at Jawaharlal Nehru University in New Delhi, A. P. Dimri, a specialist in Himalayan weather patterns, says that a freak collision of a Western Disturbance and the summer monsoon combined in the extreme rains of June, 2013 (see this paper he coauthored<\/a>). The monsoon struck southeastern India as usual, in the second week of the month. But clouds raced north and\u00a0west with extraordinary speed. The rain arrived in Uttrakhand two weeks ahead of schedule, crashing into that Western Disturbance.<\/p>\n Dimri says the two opposing systems of moisture-laden air \u201csmushed together,\u201d into a Frankenstorm that stayed pinned for two days to the southern flank of the Himalayas.\u00a0Some researchers say<\/a>\u00a0similar conditions may have loosed floods that killed 3,000 people in Pakistan and northern India in the summer of 2010.<\/p>\n Several recent research papers say that global warming may have set up Kednarath for the disaster, by transforming regional weather patterns and eroding Chorabari Glacier. Western Disturbance storms are becoming more frequent and lasting longer. The monsoon is launching its march across India earlier and traveling faster. Dimri says that global warming may be responsible for this transformation of India\u2019s weather.<\/p>\n In\u00a0a 2014 paper<\/a>, scientists at the Indian Institute of Tropical Meteorology conclude that rapid heating of the high-altitude Tibetan Plateau north of the Himalayas, caused by global warming, is rerouting Western Disturbance storms. The Tibetan Plateau has heated up faster than nearby lowlands. When patterns of heat over Earth\u2019s surfaces changes, so do the winds they drive.<\/p>\n A team led by researchers at Stanford University has the studied whether global warming made Uttrakhand\u2019s drenching month of June 2013 more likely. Using 11 leading computer models, they compared simulations of June rain with and without the last 150 years of burning coal and oil and natural gas. They\u00a0published their results<\/a>\u00a0in a special extreme weather issue of the\u00a0Bulletin of the American Meteorological Society<\/em>. The paper\u2019s lead author, Deepti Singh, a Stanford graduate student, says that of the three models that they trusted most, two showed that the June event was \u201cmore likely than it would have been,\u201d had humans not heated the planet.<\/p>\n![\"Many](\"https:\/\/dialogue.earth\/content\/uploads\/2015\/07\/Pilgrims-DSC_5233-800.jpg\")
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