Dr. Steffen was a glaciologist who did research at the world’s two largest ice sheets, Antarctica and Greenland. More than a decade ago, he led a study in Antarctica demonstrating that an icy surface the size of California had melted into the ocean.
Much of his work over the past 30 years was based on meticulous observations of changing conditions in Greenland, where in 1990 he established a research station known as Swiss Camp. A charismatic figure who began his studies in the Arctic in the 1970s, the Swiss-born Dr. Steffen organized graduate students for annual treks to Greenland. He set up a network of 20 weather stations, drilled thousands of feet deep into the core of the ice cap covering the island and documented other phenomena through satellite technology.
During much of that time, he was a professor of geography at the University of Colorado at Boulder, where he led the Cooperative Institute for Research in Environmental Sciences (CIRES), which employs hundreds of climate scientists.
“He was a giant,” said Waleed Abdalati, who was Dr. Steffen’s graduate student at Colorado and is the director of CIRES. “He had tremendous scientific credentials. He made scientific expeditions happen. He introduced generations of students to the wonders of Greenland, myself included.”
Dr. Steffen, who was widely known by his nickname “Koni” (pronounced like “Connie”), presented papers to the United Nations Intergovernmental Panel on Climate Change (IPCC) and had a flair for taking his message to political leaders and the public. Among the dignitaries who visited Swiss Camp in Greenland was House Speaker Nancy Pelosi (D-Calif.), who was part of a U.S. congressional delegation in 2007.
The same year, Dr. Steffen testified at a congressional hearing about the amount of ice Greenland was losing each year because of melting. It was the equivalent, he said, of a column of water covering the District of Columbia — and reaching almost a mile high.
“That got some attention,” he said at the time.
Dr. Steffen realized that climate was changing most rapidly in polar regions, but at first he questioned his own findings about how fast that change was taking place. During his first decade in Greenland, the average winter temperatures rose so much that Dr. Steffen did not believe his meteorological instruments. But after two decades, the evidence was irrefutable, proving that winter temperatures had risen 7.2 degrees Fahrenheit, or 4 degrees Celsius.
Among other findings, he noted that Greenland’s ice sheet lost water in two ways — melting at the surface, and a gradual slippage of glaciers toward the sea, resulting in dramatic “calving” events, in which huge chunks of ice fell off and became icebergs. The movement of glaciers was made worse because melting water seeped through the ice shelf, in essence becoming a lubricant beneath the ice pack, making it move more quickly.
When the IPCC projected in the early 2000s that sea levels could rise as much as two feet in the 21st century, Dr. Steffen begged to differ, based on what he had seen in Greenland.
“Unfortunately,” he said in 2007, “I think we are looking at more like a meter,” or about three feet.
Each spring, Dr. Steffen returned to Swiss Camp, which was built on a glacier in a forbidding polar landscape above the Arctic Circle. It sat atop a wooden platform on steel girders driven 13 feet into the ice. As the glacier below it began to shift, the entire camp moved with it, sliding 20 inches or more a day as the ice sheet drifted seaward.
“We realized that something was going wrong,” Dr. Steffen told Popular Science magazine in 2007. “Greenland was coming apart.”
He did much of the construction work himself. Ultimately, the camp contained two huts, one for a laboratory and the other for a communal dining hall. The scientists slept in tents pitched on the ice and worked long hours during the summer months, when the sun never fell below the horizon.
One of the scientists at Swiss Camp in the 1990s was Abdalati, who took a graduate course in climatology from Dr. Steffen and switched his PhD studies from aerospace engineering to geography, with an emphasis on the Arctic climate.
“He totally changed my professional trajectory,” said Abdalati, who later served as chief scientist for NASA. “When I met him, for the first time in my professional and academic life, I found myself thinking: ‘This feels right. This is what I should be doing.’ ”
Dr. Steffen slept only three or four hours a night when he was working in Greenland. He often worked barehanded as ice crystals caked his beard in temperatures that, even in the warmer months, could fall to minus-25 degrees Fahrenheit.
“I seem to like the extremes,” he said. “I am not afraid of cold.”
Konrad Steffen was born Jan. 2, 1952, in Zurich. His father was a tailor, his mother an accountant.
Dr. Steffen studied engineering before volunteering to help a glaciologist with his fieldwork in the Arctic in the mid-1970s. He then focused on geography and climate science, receiving the equivalent of a bachelor’s degree in 1977 and a doctorate in 1984, both from the Swiss Federal Institute of Technology in Zurich (known as ETH Zurich).
In the late 1970s, Dr. Steffen spent two winters on an ice floe near Baffin Island in northern Canada. He was once trapped in an avalanche and knocked off his snowmobile, suffering a dislocated jaw and a compound fracture in one leg.
He dragged himself to an aluminum stake used as a marker, pulled it out of the ice and applied it to his broken leg as a splint. He sheltered beside the overturned snowmobile, calling out the name of a fellow researcher who eventually heard his cries. After 24 hours, Dr. Steffen was rescued.
He did climate research in the 1980s while teaching at ETH Zurich and at McGill University in Montreal. He joined the faculty of the University of Colorado in 1991, eventually becoming a dual U.S.-Swiss citizen. In 2005, he became director of CIRES, which had a $50 million budget, supported in large part by grants from NASA and other federal agencies.
In 2012, Dr. Steffen returned to ETH Zurich to teach and to lead the Swiss Federal Institute for Forest, Snow and Landscape Research, known by the initials WSL. He was also a professor of architecture and environmental engineering at a sister campus, the Swiss Federal Institute of Technology in Lausanne.
His first wife, the former Regula Werner, with whom he had two children, died in 2011. He later married Bianca Perren. A complete list of survivors could not be confirmed.
The only way to reach Dr. Steffen’s remote scientific outpost on Greenland was by a series of long flights aboard a U.S. military cargo plane, then smaller aircraft and helicopters. The only sounds were the wind and, increasingly, the flowing water draining away from the melting glaciers.
“Koni had to go into the field. It was in his blood,” Abdalati recalled. “I remember the first time I saw him jump out of the helicopter on the ice. He was smiling ear to ear, and he leaned back with his long arms wide open, breathing in that bright Greenland air. He looked so happy. It wasn’t work for him. It was his passion, his joy. He changed the way we looked at the world.”
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