He knew Greenland's melting ice better than anyone. Then he disappeared into it.

Konrad “Koni” Steffen was in his favorite place on Earth when he disappeared in August 2020.

At 68, the pioneering scientist — who first sounded the alarm on how Greenland was raising sea levels across the globe — still seemed like a boyish adventurer as he stood in the middle of the ice sheet.

White snow stretched as far as the eye could see beneath a heavy gray sky. A breeze stirred up flurries. The only people for miles were his team: three young men huddling together close by. The only structure was his dilapidated camp comprised of two red hoop houses that he was still using even though they had recently collapsed due to extreme and rapid ice melt.

Koni held a data card freshly plucked from his weather station, a pole in the ice covered with solar-powered spinning gadgets and boxes that recorded precise data on Greenland’s snowfall, solar radiation, and temperature.

Once uploaded to his computer, it would provide the clearest picture to date of how rapidly and unpredictably our world is warming, helping scientists and policymakers see the future more clearly.

Koni called out as he strolled past his team: “I’m going to look at my data!”

Nobody ever saw Koni again.

Five years after his presumed death, researchers and leaders still mourn the loss of one of the founders of modern climate science. Through pioneering research methods and fearless adventurism, Koni became a close witness and powerful spokesperson on climate change. He knew Greenland’s ice sheet better than anyone — which is why his colleagues still puzzle over what happened on August 8, 2020.

Business Insider has assembled the most detailed account to date of that day, through translated police and military reports, and interviews with about two dozen of Koni’s relatives, peers, students, and admirers, including a statement from Al Gore. His children and crew shared with us never-before-seen photos of Koni’s life at Swiss Camp, the research enclave where he made discoveries that have shaped our understanding of the world.

Business Insider has also uncovered information that has never been reported publicly about what happened at Koni’s camp, the day he disappeared, and the ensuing search effort.

Koni’s story raises a harrowing question: As politicians and tech leaders set their sights on Greenland — and the rest of us watch fires and floods unfold — are we underestimating the dangers ahead?

‘It’s like a different planet’

Koni was working on the front line of the climate crisis, near Jakobshavn, one of the fastest-melting glaciers in the world.

Most of Greenland’s 56,000 inhabitants live on the fringes, where the ice sheet tapers off to bare earth. Koni operated more than 50 miles inland, where very few people venture.

For Greenlanders, “there’s a strong relation to the inland ice. There’s a strong respect. It’s a force that can mean life or death,” Anne Merrild, a professor at Denmark’s Aalborg University, who grew up in Greenland, told Business Insider.

Three times the size of Texas, the Greenland ice sheet is 680 miles wide and, on average, 1 mile deep. After Antarctica, it’s the largest mass of ice on Earth.

“It’s like a different planet,” Simon Steffen, Koni’s son and crewmember, said. “Like a white desert as far as you can see.”

The middle of the ice sheet is silent, except for the whistle of wind and the occasional pop of ice shifting deep below, Simon said. Temperatures can drop as low as -50 degrees Fahrenheit. On a really clear day at Koni’s outpost, the coastal mountains were just visible on the horizon.

Greenland is both a victim and a driver of planet-wide changes. Because temperatures are rising fastest at the poles, the ice sheet’s melt is an indicator of how rapidly the climate crisis is accelerating. It’s also the biggest contributor to sea level rise. Alone, it is projected to affect hundreds of millions of people this century, costing governments around the world trillions of dollars.

Koni uncovered climate change ground zero with maverick techniques

When Koni was a budding glaciologist in the 1970s, scientists still weren’t sure whether Greenland’s ice sheet was growing or shrinking.

Koni wanted to find out, definitively.

First, he pointed satellites at Greenland, but that didn’t provide a complete picture. So in March 1990, he said goodbye to his wife, Regula, their infant son Simon, and toddler daughter Anico, and jetted off to establish his basecamp on the ice sheet: Swiss Camp. The family got used to Koni spending each spring with this “third child” as he built weather stations across Greenland. For the first time, he combined detailed ground data with big-picture satellite observations of the ice sheet.

Related stories

Business Insider tells the innovative stories you want to know

Business Insider tells the innovative stories you want to know

His bet paid off. Within a few years, Koni had transformed glaciology and climate science. He showed that the ice was receding, melting into the ocean because temperatures were rising.

“Coming up with a network to measure the climatology and the weather patterns in Greenland was a huge breakthrough,” Santiago de la Peña, a glaciologist who took classes from Koni at the University of Colorado Boulder, said. “He was extremely experienced, but he was also a bit of a maverick.”

Koni worked tirelessly, in a flurry of espressos and cigarettes — so many cigarettes that the canine tooth where he held them went yellow. People joked that he had antifreeze for blood, and his Arctic misadventures reinforced the reputation. He fended off polar bears, fell through sea ice into frigid Arctic waters, and survived an avalanche that broke his bones and left him stranded for more than 24 hours.

He was a “tough as nails Arctic cowboy,” said Jason Box, Koni’s protégé. His unorthodox approach drew devoted apprentices, seeking adventure and discovery.

When he wasn’t advising students or collecting data, Koni traveled the world on an all-consuming campaign to make people see the catastrophe of the planet’s melting ice. He met with global leaders, spoke at conferences, led research centers, and co-authored a report of the Intergovernmental Panel on Climate Change. He would also bring film crews, friends, and politicians deep into the ice sheet to see its demise for themselves.

Koni welcomed guests to Swiss Camp with fondue and a bottle of wine in one of the red hoop houses, the kitchen tent. Then, he would occasionally trek visitors across the ice sheet on a hair-raising tour of the scariest signs of the climate crisis.

“It was really quite remarkable,” Nancy Pelosi, a US Representative and former Speaker of the House, who visited in 2007, told Business Insider in an interview this year, reflecting on her trip to see the ice melting up close. “It was: You either are paying attention to this or you are not.”

When Al Gore visited Swiss Camp in 2017 to film his climate documentary, “An Inconvenient Sequel,” Koni took the former vice president to a nearby area where rivers of meltwater gouged the surface of the ice. The scientist instructed the politician to step over a gash in the ice, so he could look down into what’s called a moulin, where the rushing blue meltwater bored a deep hole as wide as an armchair.

“That would be a hole you don’t want to step in, right?” Gore asked half-jokingly as they walked toward a much larger, roaring moulin. Koni didn’t laugh, responding simply: “Yes.”

Greenland was changing — fast

By the time Gore visited, the ice sheet was becoming dangerously unpredictable.

“One of the things that has stuck with me over the years after visiting Swiss Camp was how dangerous Koni’s line of work was becoming,” Gore told Business Insider.

A major escalation came in 2019, two years after Gore’s visit and the year before Koni’s disappearance. That spring, a visiting researcher breathlessly ran up to Derek Houtz, a childhood friend of Simon’s who had become one of Koni’s climate-science mentees. The researcher said he had stepped into a crevasse — a crack where the ice pulls itself apart. Crevasses can be several feet wide and hundreds of feet deep. In extreme cases, they reach the bottom of the ice sheet, a 1-mile drop.

Derek doubted that. There had never been crevasses near Swiss Camp — just a baby one they’d uncovered while drilling new support beams into the ice the previous spring. For years, he and Simon spun snowmobiles around the station for fun or drove hours across smooth ice, checking on other weather stations and chasing each other across the awesome landscape. They sometimes passed through crevasse fields on these longer journeys — in fact, on one such trip that season, Simon’s snowmobile had tipped backward into a crevasse. He accelerated away, feeling rattled. Derek and Koni laughed it off. Crevasses were part of life on the ice, but not at Swiss Camp.

Nevertheless, Derek grabbed a shovel and trudged to where the man pointed — until he was plunging into the snow. He clung to his shovel, which had landed flat, bridging the crevasse to form a lifesaving pull-up bar. His legs scrambled for purchase on the icy walls beneath.

“We were studying climate change. We just did not expect to see it expressed so visibly in that short of time in that spot,” Waleed Abdalati, another mentee, who succeeded Koni as director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, told Business Insider.

The US National Science Foundation, which was coordinating the group’s flights, wasn’t satisfied with Koni’s team’s ad-hoc solution — shoveling away all the snow that concealed the crevasse and, when they found it ran right under Simon’s tent, setting down a large piece of plywood to bridge the gap. The NSF sent a helicopter to retrieve everyone from the camp early.

The final trip

Koni flew into Swiss Camp with Simon and Derek on August 5, 2020, just three days before he disappeared. This trip was going to be his final goodbye to Swiss Camp before retiring, retreating to the Alps, and handing over his network of weather stations to Jason.

But that wasn’t the only reason Koni and his team were antsy as their helicopter flew over the ice sheet. This final visit was a technical challenge on a few levels.

For one thing, they usually went in the spring, after the harsh winter and before the major thaw. This time, COVID lockdowns forced them to go there after a full summer’s melt, when the ice was trickier.

Related stories

Business Insider tells the innovative stories you want to know

Business Insider tells the innovative stories you want to know

The day before they arrived, they received a photo from a film crew that had passed by. Swiss Camp, despite being designed to withstand fluctuating ice and snow levels, had fully collapsed.

More important, though, were the crevasses. Satellite imagery, which they had checked a few days before leaving, revealed the situation had deteriorated even further. Now there were three crevasses slicing past Swiss Camp.

Given the danger, Koni invited no guests and only brought his closest apprentices: Jason, Simon, and Derek. All these years, the four men had walked freely, with visitors in tow. Now they were alone and wore harnesses.

Upon landing, they patrolled the entire camp area, anchored to the helicopter with harness carabiners in case they stepped too close to a crevasse. They stuck ice probes into the ground to feel for any additional hidden fissures. Finding nothing, Koni marked a safe perimeter around camp. Nobody would be allowed to leave without being harnessed to an anchored line. They pitched their tents in the safe zone.

Koni disappeared without a sound

What happened on August 8 is not entirely clear — but this is what Business Insider has learned.

Everyone agrees it started with breakfast, a slow morning in the dome they’d set up to replace the askew red tent. Koni was in high spirits that morning, Simon said.

Simon remembers snow blowing outside, lowering visibility, but not quite a whiteout. In Jason’s memory, shared with the police, it was snowing heavily.

They started work around noon — Simon and Jason building a new weather station; Koni and Derek trudging 100 meters to the old weather station to retrieve its data card. Derek came back to help Simon and Jason, and Koni continued into camp.

Hours passed.

Around 2 p.m., Simon’s camera battery died, and he went to his dad’s tent to ask for a spare. He called toward the tent in Swiss German: “Papi!” There was no response. Koni must have been taking his afternoon nap, Simon thought. He knew better than to disturb him. Back to the weather station.

Simon checked his watch at 5 p.m. He returned to the tent to wake his father, pulled back the opening, and saw an empty cot inside.

Panic set in as Simon ran back to Derek and Jason, yelling, “Koni’s not in his tent!”

They stared at each other for a moment. They all had the same thought. Without a word, they began scrambling to harness up and run to the giant, open crevasse near camp. They yelled into it. One of them called emergency services on the satellite phone. They punched holes in the snow covering other crevasses and yelled into those, too. They called again. They found Koni’s harness in the storage tent. They probed the snow around camp in case he had collapsed somewhere.

After five hours of this, a Sikorsky S-61 helicopter arrived with two police officers, three search-and-rescue staff from the fire department, and an ice-climbing expert. The crew belayed the climber into openings in the crevasses, where he scanned for broken icicles, scrapes, or other signs that someone had fallen in.

By 2 a.m., under the Arctic sun that never sets in the summer, the crew had found no sign of Koni.

When the rescue team returned the next morning, Jason, Derek, and Simon were re-probing the snow they’d thoroughly overturned the day before. At their request, the ice climber descended deeper into the big hole in the biggest crevasse. He saw a floor of thin ice about 20 meters down, with a hole about the size of a person. Underneath, the crevasse was filled with water.

The aftermath

In the five years since his dad’s disappearance, Simon has run through every explanation his mind can conjure.

Maybe Koni couldn’t see very well. Maybe he was depressed. Maybe he was going to the latrine, dropped the data card, and carelessly lunged after it.

Then there was the incident a few nights before, when Simon and Derek awoke to the snow-crunching footsteps and scuffling sounds of what they were certain was a polar bear, but found no footprints or traces of an animal in the morning. Maybe, Simon sometimes thinks, there is truth to Greenlandic folklore, warning that ghost-like spirits — the “qivittoq” — stalk the ice sheet, capturing lost souls.

Koni’s body was never found.

The rescue team spent the rest of the day lowering a metal hook into the crevasse, trying to fish something out. They found nothing. The ice climber said it was too dangerous to send in a diver, and he determined the water was too murky for a GoPro.

“I wish we could really know what happened,” Simon said. “But in the end, it doesn’t really matter. He ended up disappearing on the Greenland ice sheet because the Greenland ice sheet has been completely changed and deformed, and morphed from what he was used to.”

In the five years since Koni’s disappearance, Greenland has become one of the most geopolitically important places on Earth. The melting Arctic sea ice surrounding the island is opening new shipping and military routes, which has stoked the expansionist appetite of Donald Trump and Silicon Valley tech investors. Reuters recently reported that they are pitching to turn Greenland into “a libertarian utopia.”

In some ways, Koni’s death was an anomaly. In others, a warning.

“He confronted the reality of this crisis every day. It was that reality that spurred him to be an ambassador for action,” Gore told Business Insider. As more of us find ourselves on the front lines, he added, “We must come together and transform the despair we feel about the climate crisis into action.”

Koni lived and died on the front lines of a dangerous future that’s rushing toward us all: The world we knew is melting away.