This article was supported by Rolex, which is partnering with the National Geographic Society on science-based expeditions to explore, study, and document change in the planet's most unique regions. A version of this story appears in the July 2020 issue of National Geographic magazine.

Everest Base Camp, Nepal—Just after dawn on May 23, 2019, two climate scientists, Tom Matthews and Baker Perry, stood on the Southeast Ridge of Mount Everest at 27,650 feet, on the verge of making history. They had spent months preparing for this moment: the installation of the highest weather station in the world.

Mt. Everest 29,035 ft 8,850 m Lhotse 27,940 ft 8,516 m Balcony Station 8,430 m Triangle Face South Col Station 7,945 m South Col South Col Station 7,945 m Camp IV North Face Lhotse Face Changtse 24,879 ft 7,583 m Southwest Face North Col Camp III Nuptse 25,791 ft 7,861 m Camp II Station 6,464 m West Shoulder Camp II Camp I Mt. Everest is one of the few peaks high enough to break into the South Asia jet stream—a poorly understood, yet important band of high-altitude winds. PLATEAU OF TIBET Pumori Bench Station 5,315 m Mt. Everest Direction of view ASIA Mt. Everest Lhotse Everest Base Camp China Phortse Station 3,810 m NEPAL South Asia jet stream Lukla Base Camp 10 mi 10 km SCALE VARIES IN THIS PERSPECTIVE. THE STANDARD SOUTH COL ROUTE IS APPROXIMATELY 9 MILES (14.6 KILOMETERS) LONG. SOREN WALLJASPER, NG STAFF; SOURCE: NATIONAL GEOGRAPHIC SOCIETY; GERMAN AEROSPACE CENTER Mt. Everest is one of the few peaks high enough to break into the South Asia jet stream—a poorly understood, yet important band of high-altitude winds. ASIA Mt. Everest China NEPAL South Asia jet stream PLATEAU OF TIBET Pumori Bench Station 5,315 m Mt. Everest Direction of view Lhotse Everest Base Camp Phortse Station 3,810 m Lukla 10 mi 10 km Mt. Everest 29,035 ft 8,850 m Balcony Station 8,430 m Camp IV North Face South Col Station 7,945 m Southwest Face Camp III Camp II Station 6,464 m Camp II Camp I SCALE VARIES IN THIS PERSPECTIVE. THE STANDAR SOUTH COL ROUTE IS APPROXIMATELY 9 MILES (14.6 KILOMETERS) LONG. SOREN WALLJASPER, NG STAFF; SOURCE: NATIONAL GEOGRAPHIC SOCIETY; GERMAN AEROSPACE CENTER

Their team had worked closely with a crew of engineers to meticulously construct the seven-foot-tall, 110-pound structure to withstand the extreme cold and hurricane-force winds it would face on the highest point of the planet. They had tested it in New Hampshire and Nepal, and then had painstakingly practiced erecting it as quickly and efficiently as possible with their team of six Sherpa. They knew that the lack of oxygen and effects of exhaustion would give them a maximum of three or four hours to get the station up and working before they had to descend.

Now, with the sun beginning to rise over the Tibetan plateau, everything seemed to be coming together. Even the season’s notoriously fickle weather was cooperating. But as Matthews and Perry unpacked their gear, a terrible truth began to sink in: a key piece was missing.

Data is in the Clouds In 2019, members of the National Geographic and Rolex Perpetual Planet Everest Expedition set out to install five new weather stations on Mt. Everest, including the highest weather station on Earth. Follow along as the team climbs into the mountain’s “death zone” to complete the network of weather stations in order to improve our understanding of climate change.

To lug the weather station to top of the world had required parceling its pieces out among the members of their team. And among the coils of guy-wire, aluminum poles, and various scientific instruments, there was supposed to be two short sections of metal tubing that connect the wind sensors to the main structure. The men searched and re-searched the packs, but it was nowhere to be found. They stared at each other, both simultaneously turning over this fact in their oxygen-deprived brains and seeking a solution.

The reason any of this was worth the effort, risk, and cost is because only Mount Everest and a few of its Himalayan cousins are tall enough to reliably pierce the Sub-tropical Jet Stream—one of the narrow bands of powerful winds that circle the globe at high altitudes, influencing everything from storm tracks to agriculture growing seasons. For climate scientists, there are few more pressing phenomena to understand than the jet stream, and the weather station would provide scientists an important new tool with which to gather data about it.

And yet there they were, on the roof of the world, with no way to attach the wind sensor—the most important part of the station.

View Images Tents sprawl across Everest's camp 2. A team of geologists, glaciologists, biologists, cartographers, and climate scientists—along with climbing guides and Sherpas—came to the mountain during the 2019 spring season to undertake extensive, multi-disciplinary scientific work, including erecting the world's highest weather station and pulling a 10-meter-long ice sample. Photograph by Eric Daft, National Geographic

A new window on the planet

Matthews and Perry had come to Everest as part of an ambitious scientific assessment of the mountain. The National Geographic Society, working in partnership with Tribhuvan University, the Government of Nepal, and funded by Rolex, launched the two-month expedition, which ultimately involved more than 30 scientists conducting fieldwork at various elevations on the mountain as well as across the rugged Khumbu Valley.

“This is a new window into the planet,” said Paul Mayewski, director of the Climate Change Institute at the University of Maine and the expedition's scientific leader. “We believe the best way to do science on Everest isn’t just to do one kind of science, but do many kinds of science.”

The multi-disciplinary group included geologists, glaciologists, biologists, cartographers, and climate scientists, who set out to collect hundreds of water, snow, and rock samples as well as install sensors to record vegetation growth, and survey the landscape using high-resolution laser technology.

While the bulk of the team’s work would happen at base camp or lower elevations, Mayewski had challenged Matthews, Perry, and climate scientist Mariusz Potocki to climb to the summit for scientific purposes. Aided by a strong support team of Sherpa, the group hoped to install weather stations and drill ice cores at both the South Col and the summit. The two weather stations (part of a network of six the team would establish on and around the mountain) would be the world's highest.

The herculean task of conducting field science at 29,035 feet demanded months of preparation and planning. Specialized equipment needed to be designed, built, and tested, while the team trained for the rigors of not only climbing the world's tallest mountain, but also the physical effort required to set up the weather stations and drill the cores.

“No one's ever done field science above 7,000 meters,” Mayewski said simply. “Everything is very different up there.”

View Images Chris Millbern operates a drone to complete the most detailed photogrammetry data collection of Everest base camp ever attempted. The study will use aerial photography to calculate measurements and distances, helping to create a more accurate map of the area. Photograph by Mark Fisher, National Geographic

Based on exclusive access to the team’s base camp and scores of interviews with its team members, this is their story.

Bad news for the Himalaya

“Climate change operates differently in different parts of the world,” Paul Mayewski told me one afternoon as he sat in the communications tent at base camp on the Khumbu Glacier. It was the third week in May, and snow flurries drifted among the moraine crests outside, softly padding the tent’s orange and black fabric. A bearded 72-year-old with youthful features and unkempt, silver hair, Mayewski spoke in no-nonsense bursts.

“This is one of the faster warming continental regions in the world, but we don’t know what’s really going on above 5,000 meters,” he continued, “and these mountains are the water towers of the planet. Between 20-25 percent of the world’s population gets their water from the Himalaya.”

View Images Headlamps illuminate the path climbers take up the Khumbu Icefall from base camp. The weather stations erected by the team follow a similar path, spanning the distance from the village of Phortse to Everest's Balcony. Photograph by Eric Daft, National Geographic

Three months earlier, in February 2019, the International Center for Integrated Mountain Development released the Hindu Kush Himalaya Assessment, a landmark report five years in the making. Collecting and analyzing data from 350 researchers and policy experts, the study forecast what is likely to happen to the Greater Himalaya, and its inhabitants over the next 80 years as the Earth continues to warm.

Even if the global community met the most ambitious carbon-reduction goals laid out by the Paris Agreement, the report warned, one-third of the region’s approximately 10,000 glaciers will be gone by the end of the century. For the 250 million people who live across the mountain region—and the 1.6 billion people who depend on the water which flows from it—the report spelled out an enormous cataclysm that many will witness in their lifetimes.

“As we begin to put together a better understanding of what the future will be like, understanding what is happening between 5,000—8,800 meters will become extremely important,” Mayewski explained. Virtually all the glaciers in the Himalaya originate in snow deposit zones above 5,000 meters, meaning that scientists can’t put together an accurate picture of how fast the region's glaciers are melting until they venture above 5,000 meters to understand the environment where glaciers are being formed.

“We will have just that much better understanding of how the hydrosphere—the water system—will react with increased change,” Mayewski continued. “How the winds will change and where the jet stream is. It’s critical throughout the northern hemisphere.”

Early in his career, Mayewski embarked on a series of expeditions to Antarctica, traversing the Transantarctic Mountains several times, and to the North Side of Everest, where he took ice cores at 6,500 meters. “I always wanted to be an adventurer, an explorer first,” he said. “It wasn’t until 10 years after I earned my Ph.D. that I began to think of myself as a scientist. I actually get annoyed that most people think of scientists as being lab nerds.”

As Mayewski spoke, he kept one eye on a radio handset, his only connection to the summit team now climbing high on the mountain. He confided that it was hard not to be with them. “I like to be a leader who actually leads, and is in the front. But I accept the fact that we have really good people, and we can only tell them so many times ‘please be careful about this.’”

He added, “Probably the biggest wild card has been the crowds on the mountain this year.”

Extreme drills and indestructible tripods

Conducting “meaningful field science,” as Mayewski put it, in the environment above 8,000 meters presents several uniquely daunting challenges.

At extreme altitudes, a mountaineer's fine motor control and high-level decision making are frequently impaired. Erecting a weather station or drilling a 10-meter ice core are both activities that require several hours of rigorous effort under the best conditions. On the upper reaches of Everest, one must work wearing both an oxygen mask and mittens, or risk disorientation and frostbite.

Then there's the not insignificant logistical matter of ensuring that all the necessary equipment is transported up the mountain and all the ice samples are moved safely down and then remain frozen as they are taken from Nepal to the U.S. and deposited in the custom-built freezers at the University of Maine's Climate Change Institute.

“Mountaineers are just hoping to summit, take a few selfies, and then get down as quickly as possible,” explained Pete Athans, a seven-time Everest summiteer and the climbing leader of the team. “This is like stopping on the summit and trying to assemble a car.”

To design and install a series of automated weather stations at various altitudes, Mayewski recruited Baker Perry, a tall, taciturn climate scientist from Appalachian State University, who once played professional basketball in Bolivia, and Tom Matthews, a quick-talking English climatologist and avid marathoner from Loughborough University.

View Images Inka Koch takes a surface snow sample from near the summit of Lobuche. The Himalaya provide water to approximately a quarter of the world's population and scientists hope to use data from the expedition to better understand the impact of climate change on the mountain and its resources. Photograph by Mark Fisher, National Geographic

“You can’t really make a bulletproof station,” Perry told me. “Especially with solar panels and radiation shields, you’re limited by the sensors that are available.” An Italian research team installed a weather station at the South Col a decade ago, only to have it shredded by small stones picked up by the wind and blasted like shrapnel into the equipment. Perry and Matthews ultimately partnered with the design team at Campbell Scientific to help them engineer and build six weather stations.

The first main challenge is engineering a tripod light enough to carry up but also strong enough to survive what could easily be 200-plus mile an hour winds, Perry told me. And the second is how to build a reliable satellite link to transmit the data in real time from the station.

As Perry and Matthews worked on the latest iteration of the tripod, Mariusz Potocki, a Polish climate scientist who works with Mayewski at the University of Maine, was busy developing a special drill—light enough to haul to the summit of Everest yet powerful enough to cut through rock hard glacial ice and collect the highest ice core ever recorded.

Similar to the rings that record the growth of a tree, layers of ice contain historical records of the chemicals present in the atmosphere when the water droplets froze. With the data derived from an ice core, Mayewski and Potocki hoped to study the deep record of precipitation on the mountain and also the composition of the atmosphere during pre-industrial times—critical information that would help provide a baseline for assessing current climate trends.

“The problems were how to power the drill and how to transport the ice chips up around the barrel,” Potocki said in clipped English. “When you’re drilling, you’re scraping ice around the core. So it’s very important to smoothly transfer the chips up to the top and over the barrel, or else, especially in wet ice, the drill gets stuck.” Potocki made a flat belching sound to mimic the sound of a stuck drill. “That can be game over.”

In a large research freezer kept at minus 13° F at the University of Maine, Potocki tested five different cordless drills to determine which battery held the best power and longevity in extreme cold. Then he, Mayewski, and two colleagues traveled to Iceland to test the entire system. And then the entire team of scientists who would climb Everest traveled to Nepal in January to conduct dry runs of their respective experiments and practice with a crack team of climbing Sherpa led by Panuru Sherpa, a 17-time Everest summiteer.

“We understand what the work is all about,” Panuru said. “We’ve been seeing the changes in our valley our whole lives, so we want to help.” And besides, he added, “Sherpas are used to working with tools.”

Forecasts and frozen fingers

When the team arrived at base camp in mid-April, they joined a record number of mountaineers hoping to cross off the world’s highest peak from their bucket lists. According to Everest blogger Alan Arnette, Nepal's Ministry of Tourism issued 382 climbing permits and 390 support permits for a total of 772 people attempting to get to the summit during the 2019 spring season, which generally lasts until around the end of May.

Furthermore, all of these climbers would be closely watching the erratic weather, looking to time their summit attempts for the few days each season when the winds abate and the skies clear. With so many climbers, the route to the top could create dangerous traffic jams high on the mountain and potentially lead to tragedy.

Prolonged good weather was especially crucial for Perry and Matthews to put up the weather station and for Potocki’s ice core drilling. Not only did they need enough good weather to safely reach the summit—and get down—but also to spend several hours working there. Ultimately, weather and crowd behavior would determine much of the team’s chances for success.

“There’s limited space close to the summit to actually do things, even with oxygen,” Mayewski explained. “We need space to work. It would only take one person—not even in our group—to completely derail that.”

HOW TO MEASURE EXTREME WEATHER National Geographic Society sent scientists to Everest to deploy five long-term weather stations to evaluate weather in “the death zone” (above 8,000 meters or 26,247 feet) as well as to learn how the mountain is responding to climate change. Each station was broken down into the smallest components and carried by multiple Sherpas, so as a whole each station had to be lightweight but strong enough to withstand extreme weather. They were also designed to be installed quickly in the challenging environment. Total weight: approximately 50 kg (110 lb) Lightning protection device Reduces direct lightning strikes, protecting the electronics Wind monitor Track wind speed and wind direction Shovel handle When both mounts for the wind sensors were missing for one of the stations, they improvised with handles from a collapsable shovel instead. Air temp. and relative humidity sensor Air temperature sensor Net radiometer UV, visible, and infrared radiation sensor Satellite Communication Radio antenna Solar Panels Protective cases Houses the datalogger, barometric pressure sensor, radios, and battery Bolts anchoring the feet into the rock Composite station shown. TAYLOR MAGGIACOMO, NGM STAFF. SOURCES: CAMPBELL SCIENTIFIC; NATIONAL GEOGRAPHIC SOCIETY HOW TO MEASURE EXTREME WEATHER National Geographic Society sent scientists to Everest to deploy five long-term weather stations to evaluate weather in “the death zone” (above 8,000 meters or 26,247 feet) as well as to learn how the mountain is responding to climate change. Each station was broken down into the smallest components and carried by multiple Sherpas, so as a whole each station had to be lightweight but strong enough to withstand extreme weather. They were also designed to be installed quickly in the challenging environment. Total weight: approximately 50 kg (110 lb) Lightning protection device Reduces direct lightning strikes, protecting the electronics Wind monitor Track wind speed and wind direction Shovel handle Air temperature and relative humidity sensor Shovel handle When both mounts for the wind sensors were missing for one of the stations, they improvised with handles from a collapsable shovel instead. Air temperature sensor Satellite communication device Radio antenna Solar panels Net radiometer Ultraviolet, visible, and infrared radiation sensor Protective cases Houses the data logger, barometric pressure sensor, radios, and battery Bolts anchoring the tripod feet and cases into the rock Composite station shown. TAYLOR MAGGIACOMO, NGM STAFF. SOURCES: CAMPBELL SCIENTIFIC; NATIONAL GEOGRAPHIC SOCIETY

“You have to avoid self-inflected wounds on crowded days, like taking too long and running out of oxygen,” Athans said, “or you could end up getting involved in rescuing someone else and run out of oxygen.”

By May 19, with the traditional summit window at hand, the weather forecasts remained iffy. But the models predicted the winds would subside in a couple days, so Matthews, Perry, Potocki, and their team of climbing Sherpa led by Panuru packed up and departed base camp for the three day climb to the South Col.

In search of ancient ice

Potocki’s first target was a small remnant glacier clinging to the north side of the South Col. It’s the first stretch of ice encountered when leaving camp 4 bound for the summit. Mountaineers regard it as a moderate obstacle, but to Potocki it represented scientific gold—ancient, undisturbed, relatively clean ice.

View Images Scientists built the weather stations on Everest, including this one at camp 2, to send automated data by satellite, avoiding the need to physically reach the station to download information. Photograph by Eric Daft, National Geographic

As soon as the drill bit into the ice, Potocki, broke into a smile. The exceptionally cold, dry conditions at 8,020 meters made for brittle ice chips, which cleared easily around the barrel of the drill, ensuring a clean core. “I knew it would be very enjoyable drilling,” he said with a laugh. “You know from experience how the drill behaves.”

The team steadily removed approximately 50-centimeter lengths of core at time, packaging each sample in a white cardboard poster tube and adding extensions to the drill as the hole grew deeper. As they drilled, Matthews and Perry and a contingent of six Sherpa were busy erecting the weather station on the other side of the Col.

By early afternoon, the ice coring team had returned to camp, having drilled a 10-meter section of ice.

Back in his tent but too jazzed to rest, Potocki realized that a second core, taken from ice at the foot of the glacier, would provide a full picture of the glacier’s age, which he and Mayewski estimated could be 5,000 to 10,000 years old. “I said, ‘oh no, I will not leave it that easy; I want more ice,’” Potocki recalled.

He returned to the glacier to take a second core. “I went 2.2 meters, down to bedrock,” he says. “Now we have the top and the bottom of the glacier, so we can determine how old the glacier is and see accumulation rates.”

As Potocki celebrated his ice haul, Matthews and Perry had returned from successfully installing the South Col weather station—the world’s highest. Instead of rejoicing, they lay fretting in their tent, worrying the weather would prevent them from setting up the second weather station on the summit. “We had two conflicting forecasts,” Matthews recalled, “and one indicated the winds were going to be more unfavorable.”

As the afternoon wind rattled their tent, they somberly considered aborting their summit attempt. Both scientists felt their mission was somehow incomplete without at least venturing higher. “I felt it would be a really sad conclusion to the summit push,” Matthews said. “I really wanted the weather to allow us to start up.”

View Images Climbers stand by their tents at Camp 4 on Everest's South Col, where one of the team's weather stations was installed. The stations were rigorously tested in New Hampshire and Nepal to ensure they would withstand the mountain's harsh environment, holding up against heavy winds and storms. Photograph by Baker Perry, National Geographic

By nightfall, the winds had subsided and a new, favorable forecast arrived. The team left at 11:30 p.m., planning for a seven- to eight-hour ascent to the summit.

Saved by a shovel handle and duct tape

As Perry, Matthews, Potocki, and their team of Sherpa left the South Col, a high deck of clouds passed over the mountain, and it began to snow intermittently, casting everything in a chalky darkness.

“We made good progress off the bat, but then we hit the back of the line,” Perry said. A line of dozens of mountaineers, some of whom had left Camp 4 as early as 5 p.m., had come to a near standstill at a part of the route known as the Triangle Face.

“It wasn’t totally unexpected. We had seen some of this in the icefall and going up the Lhotse Face,” Perry reflected. “But it was frustrating for the Sherpa team because we couldn’t all just unclip and zip past these people. The slower you move, the colder you get.”

After two hours of stop-and-go traffic, the team reached the Balcony—a flat section where the climbing route intersects with the crest of the Southeast Ridge.

“We saw the line of people ahead of us,” Perry said, “and realized what we were up against. When we moved to May 23rd, that just put us in the middle of two very busy summit days.”

“You're trying to maximize your team's advantages by going on the best summit day,” Pete Athans explained. “The strong irony is everyone else is trying to do the same thing.”

Panuru, Perry, and Matthews had already discussed the Balcony as an alternative site for the weather station in the event reaching the summit wasn’t feasible. Now, they quickly shifted focus to setting it up. “There was some disappointment, yeah,” Perry recalled, “but none of us was there to summit Everest.”

“It was the hardest moment because so much effort had gone into it,” Potocki said. He was perhaps the most frustrated: The snowpack around the Balcony was too contaminated by human waste and discarded oxygen bottles to drill a core. “Seeing so many unqualified people, everyone going up like flies to honey,” Potocki said, shaking his head, “Damn, there were too many people.”

As Potocki fumed, Perry and Matthews discovered the batteries in the hammer drill that would drive in the weather station’s anchor bolts were dead from the cold. Matthews and one of the Sherpa, Phu Tashi, each stuck a battery inside his down suit to warm it. The sky slowly brightened as they waited.

“It was one of those anticlimactic moments,” Matthews said, laughing. “We’re standing stark still, with batteries stuck down our crevasses. It took a long while, but it worked.”

With the anchor bolts in, the system went up smoothly. “We had built the South Col station the day before,” Perry said. “Our Sherpa team knew how to do almost everything.”

Then Perry realized the mounts for the wind sensor were missing. They had the cross arm fixed horizontally to the mast, but no way to attach the wind sensor to the cross arm.

“We couldn’t go down without putting on the wind sensors, and we weren’t going to send someone down to get them,” Perry said. “So, we started brainstorming.”

Perry realized that the handle to a lightweight aluminum mountaineering shovel the team had brought was roughly the same diameter as the missing mounts. “I’ve had to deal with different diameter tubes in the field before,” he said, “so, I had some experience with this.”

There was one issue: the shovel handle was oval, while the attachments on the cross arm were machined for circular tubing. One of the Sherpa, Lhakpa, grabbed a lightweight hammer and began to pound the handle into a circle. Then Perry wrapped strips of duct tape around it to increase the circumference, making the fit tighter.

“It’s a super modern weather station,” said Matthews. “But you look closely, and there’s a bunch of duct tape and a florescent orange and blue shovel handle.”

View Images The team celebrates the success of their final weather station installation, which has already begun to send data back to a National Geographic server. Photograph by Mark Fisher, National Geographic

As the team prepared to descend, Perry took a final look at the newly constructed station before turning his gaze toward the summit. By then, the long line of climbers had advanced, and for a moment Perry wondered if he and the team could have gone higher. He quickly dismissed the thought and turned to begin the lengthy descent.

The lab work begins

While the group made their way back to base camp, the weather stations were already transmitting data to a National Geographic Society computer server.

Potocki's ice cores were helicoptered from camp 2 to Kathmandu, where they went into storage in the deep freezer unit at the American Club. They will soon be flown to the U.S. and driven in a specially chartered freezer truck from the customs office at John F. Kennedy International Airport to the Climate Change Institute in Maine.

It will take months before the true scope of the fieldwork is understood.

Despite the overcrowded, high-stakes environment on Everest, all three scientists see reason to return. “It would be worth going back with radar to learn more about this glacier and to drill all the way to the bottom,” Potocki said. “But my wife said she'd divorce me.”