Lonnie Thompson, Paleoclimatologist Who Read Climate History in Tropical Ice, Dies at 78

Lonnie Thompson, the pioneering paleoclimatologist who spent half a century extracting ancient climate records from the world's most inaccessible tropical glaciers, died on November 2, 2026, at his home in Columbus, Ohio. He was 78 years old.[1][5]

Over a 55-year career at Ohio State University, Thompson led more than 60 expeditions to high-altitude ice fields across 16 countries. His work transformed scientific understanding of Earth's climate history and provided unmistakable evidence of human-caused warming.[1][5]

Working alongside his wife and research partner, Ellen Mosley-Thompson, he built the ice core paleoclimatology research group at the Byrd Polar and Climate Research Center. Together, they amassed an archive of more than 7,000 ice cores, securing physical records of the atmosphere before the glaciers melted.[3][5]

Thompson's death followed a brief illness, according to announcements from Ohio State University. His passing marks the loss of a scientist who fundamentally changed how humanity understands its impact on the planet's atmospheric systems.[2][3]

Reading history in tropical ice

When Thompson began his career in the 1970s, the scientific consensus held that tropical glaciers could not preserve long-term climate records. Researchers believed that seasonal melting and warmer temperatures would blur the distinct layers of ice needed to track historical atmospheric changes.[1][5]

Thompson rejected this assumption, arguing that the extreme elevation of tropical ice caps kept them frozen solidly enough to trap ancient data. In 1974, he launched his first expedition to the Quelccaya ice cap in the Peruvian Andes to test his hypothesis.[5]

The work required inventing entirely new methodologies. Because heavy drilling equipment could not be airlifted to altitudes above 18,000 feet, Thompson and his team engineered lightweight, solar-powered drills that could be transported by pack animals and operated in thin air.[5]

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In 1983, after years of failed attempts and logistical hurdles, his team successfully extracted two deep ice cores from Quelccaya. The samples contained dust, chemical isotopes, and trapped gases that documented regional weather patterns dating back 1,500 years.[5]

The New York Times noted that Thompson "dodged avalanches to preserve climate history," highlighting the severe physical toll of his research. The Quelccaya breakthrough proved that tropical ice could serve as a reliable climate archive, opening a new frontier in paleoclimatology.[1]

The mechanics of an ice core

Glacial ice functions as a vertical timeline of Earth's atmosphere. As snow falls and compresses into ice over millennia, it traps microscopic air bubbles, volcanic ash, pollen, and chemical isotopes from the exact moment it was deposited.[5]

By drilling vertically through a glacier to the bedrock, scientists extract cylindrical cores that can be analyzed layer by layer. The ratio of oxygen isotopes in the ice reveals historical temperatures, while trapped greenhouse gases show the atmospheric composition of the past.[5]

Tropical glaciers are particularly valuable because they sit near the equator, where the majority of the planet's heat and moisture exchange occurs. Unlike polar ice, which records high-latitude conditions, tropical cores capture the climate dynamics that directly affect billions of people.[1][5]

Thompson's samples revealed that the rapid warming observed in the late 20th century was entirely unprecedented in the context of the last several millennia. The chemical signatures in the ice showed a stark departure from natural climate variability.[1][5]

His data provided a crucial independent verification of global warming, separate from instrumental temperature records. The ice cores demonstrated that the atmospheric changes driving modern warming were directly linked to human activity.[1]

Because the ice cores captured both the natural baseline of the Holocene epoch and the sudden spike of the industrial era, they left no room for ambiguity. The physical evidence proved that the Earth's climate was changing at a rate unseen in human history.[1][5]

A vanishing climate archive

As Thompson collected his cores, he simultaneously documented the rapid destruction of the very glaciers he was studying. By returning to the same high-altitude sites over decades, he measured the physical retreat of the ice with alarming precision.[1][5]

In 2001, Thompson published a stark prediction regarding Mount Kilimanjaro in Tanzania. Based on his measurements, he warned that the mountain's famous snows, which had already shrunk by 80 percent during the 20th century, would largely disappear within two decades.[5]

This observation shifted his mission from pure exploration to an urgent salvage operation. Recognizing that the world's tropical glaciers were melting rapidly, Thompson raced to extract cores from endangered ice caps in Papua, Indonesia, and the Himalayas before the records melted away entirely.[5]

The resulting archive, stored in massive freezers at Ohio State University, ensures that future scientists will have access to physical climate records that no longer exist in nature. The collection represents one of the most comprehensive climate libraries in the world.[3][5]

"His observations helped establish shriveling mountain glaciers as an unmistakable consequence of human-caused warming," the New York Times reported, cementing his role as a central figure in modern climate science.[1]

From West Virginia to the Andes

Born on July 1, 1948, in Gassaway, West Virginia, Thompson grew up on a farm in a rural, coal-mining region. He initially intended to study coal geology, viewing it as a practical path out of poverty.[5]

He earned his undergraduate degree in geology from Marshall University, where he met Ellen Mosley, a physics student who would become his wife and lifelong scientific collaborator. The couple married and moved to Columbus to pursue graduate studies at Ohio State.[5]

During his first term in 1971, Thompson took a research position analyzing polar ice cores at the Institute of Polar Studies. The work diverted him from coal geology and launched his five-decade career in glaciology.[4][5]

He received his master's degree in 1973 and his doctorate in 1976, remaining at Ohio State for his entire academic career. The university recently noted that Thompson "touched thousands of lives across the globe through his tremendous community engagement."[3]

A legacy of scientific endurance

Thompson's dedication to field research was legendary within the scientific community. He spent more time above 18,000 feet than almost any other human, enduring extreme cold, thin air, and severe physical strain to recover his data.[5]

His resilience extended beyond the mountains. In May 2012, Thompson underwent a successful heart transplant, yet he eventually returned to high-altitude fieldwork, refusing to abandon the research that defined his life.[5]

Over his career, he received numerous accolades, including the National Medal of Science in 2007 and the Benjamin Franklin Medal in 2012. His life and expeditions were recently chronicled in the 2023 documentary film "Canary."[5]

Despite the prestigious awards, Thompson remained focused on the raw data. He viewed the ice not just as a scientific curiosity, but as a critical warning system for a global civilization heavily dependent on stable weather patterns.[1][5]

Thompson is survived by his wife, Ellen Mosley-Thompson, and their daughter, Regina. The Byrd Polar and Climate Research Center stated that the university and its partners "will now do their best to honor and carry on his legacy."[3]

The thousands of ice cylinders resting in the freezers in Ohio serve as his most enduring monument. They hold the atmospheric history of a planet in transition, secured just before the ice began to vanish.[1][3]