For the first time since 1974, nobody reached the top of the world's tallest mountain last year - a period during which tragedy, government actions and plain old bad luck made Mount Everest virtually unconquerable.
The news was confirmed for The Washington Post by climbers, longtime Everest observers and the Himalayan Database, which compiles records for expeditions into the Nepalese Himalaya.
Although climbers say multiple obstacles hampered their ascent in 2015, none was bigger than an earthquake-spawned avalanche that killed 24 people on Everest in April, turning an otherwise ordinary morning into the the deadliest day in the mountain's grim history. The 7.8-magnitude quake - which struck near Nepal's most densely populated area - killed more than 8,000 people and injured 21,000 others as it leveled much of Kathmandu and poorly developed rural regions outside the capitol.
"While the Nepal government never officially closed Everest to climbing, it was practically shut off as the primary climbing route goes through the Khumbu Icefall and the Sherpas who managed the route stopped maintaining, it given the danger," Alan Arnette, a mountaineering journalist who was on Everest when the earthquake struck, told The Post. "Also, almost every team made the independent decision to halt climbing due to the excessive risks."
"On the Tibet side," Arnette added, "the Chinese government, through the China Tibet Mountaineering Association (CTMA), made the decision to close all climbing throughout Tibet, including Everest, the day after the earthquake and through the remainder of 2015 due to potential aftershocks and excessive risks."
In October, a one-fingered Japanese climber attempting to reach the top of Mount Everest was forced to turn back when conditions became too dangerous, according to Yahoo News. Nobukazu Kuriki, who lost nine fingers on the mountain in 2012, was trying to become the first person to summit the 29,029-foot peak since the April avalanche.
"Did my best, but figured will not be able to return alive if I go further due to strong wind and heavy snow," the 33-year-old wrote on Twitter that month, according to Yahoo.
Last year was the second in a row in which major tragedies struck the mountain. In 2014, 16 Sherpas were killed in an avalanche that was triggered when a massive ice serac was released just above base camp in the Khumbu Icefall, according to Arnette. The avalanche struck a group of about 50 people at more than 20,000 feet, Tilak Ram Pandey of the ministry's mountaineering department, told CNN.
As recently as 2013, hundreds of climbers were making their way to the summit each year, according to the Himalayan Database. That year alone, according to database figures, 658 climbers reached the top of Everest. Eight people were killed on the mountain in 2013.
As reported earlier, some researchers believe that climate change could shrink the mountain's glaciers by as much as 70 percent.
"The research also suggests that this melting process could, on occasion, lead to sudden large discharges of water from gigantic melt lakes atop the glaciers - not good news for a region that just suffered from a devastating earthquake," Mooney wrote.
Phil Powers, the CEO of the American Alpine Club, told The Post that if the mountain becomes more unstable, the danger for climbers will only intensify. Everest has no shortage of dangerous areas, Powers said, but one of the most precarious is the Khumbu Icefall, a slow-moving river of massive, cracking ice chunks and crevasses that climbers must negotiate after they leave base camp and climb to Camp 1.
"If the icefall continues to get worse and more dangerous and harder to pass through, you can imagine a future where the number of people climbing Everest is much reduced," Powers said.
The deadly avalanches in 2014 and 2015 have convinced Powers that mountaineering on Everest is entering a new era. After eight people were killed in a notorious storm in 1996 - an incident chronicled in John Krakauer's bestseller "Into Thin Air" and the 2015 film "Everest" - climbers resolved to change how the increase in commercial activity was managed on the mountain.
Two decades later, Powers said, the challenges facing climbers are beyond human control.
"If the average temperature of the world is warming, then the fluctuations from that average are going to be higher, and those changes are being seen on the mountain," he said. "Simply put, it's just going to get harder and harder to cross that glacier."
Over time, the number of climbers might be reduced. But if the response to the deadly 2014 climbing season is any indication, last year's avalanche may not necessarily slow the stream of climbers willing to try their luck on Everest. Arnette noted on his blog last year that concern that the 2014 avalanche might deter would-be climbers proved unfounded.
"However, history shows us once again that it is a fine predictor of the future," Arnette wrote. "After record deaths in 1996, 2006 and 2012, the following year delivered record climbers on Everest; 2015 was no different. Even on Everest from Tibet for 2015, records permits were issued, over 200 foreigners ."
"In my opinion," Arnette said this week, "the recent tragedies will not stop the desire to climb Everest or other high mountains, as most people who climb accept the risks. There are some in the Sherpa community that have decided to stop guiding on Everest due to the increasing danger and pressure from their families, but the economic benefit of guiding Everest often outweighs the risks."