An Old Dominion University alumnus whose groundbreaking discovery transformed multiple fields of science has received one of the nation's oldest and most prestigious scientific honors.
Mark Thiemens, Ph.D. (M.S. ’ 75), is the 2026 recipient of the Magellanic Premium, awarded by the American Philosophical Society for extraordinary achievement in science and discovery.
Dr. Thiemens is being recognized for discovering mass-independent isotope fractionation in 1983, along with colleague John Heidenreich. The breakthrough changed how scientists investigate Earth's atmosphere, planetary processes and environmental change. His research has advanced fields ranging from climate science and environmental monitoring to planetary exploration by providing scientists with new ways to understand Earth and the solar system.
"While the work involves isotopes and a lot of quantum-level physics, the concept is easy," Dr. Thiemens said. "By measuring the isotopes of oxygen and understanding how their proportions change, we can determine what happened during natural processes. That might mean tracking greenhouse gas emissions, studying the origin of the solar system through meteorites or investigating how life evolved in Earth's oldest rocks."
The Magellanic Premium is among the rarest scientific honors in the world. Established through a bequest from scientist and explorer Jean-Hyacinthe de Magellan and first awarded in 1790, the prize has been presented only 43 times in nearly 250 years. Dr. Thiemens recently received the award in London during the American Philosophical Society symposium, which was held in partnership with the Royal Society, the United Kingdom's national academy of sciences.
While the award recognizes a lifetime of achievement, the discovery at the center of Dr. Thiemens' career began with a fundamental question about how isotopes behave.
Isotopes are atoms of the same element that differ slightly in mass. Before Dr. Thiemens' work, scientists believed isotopes behaved in predictable ways during chemical reactions. His research revealed that under certain conditions, isotopes could behave differently than expected, leaving behind unique chemical signatures that became powerful scientific tools.
Researchers have since applied those principles to investigate atmospheric ozone chemistry, track environmental pollutants, study glacial ice records, explore the origins of planetary-scale atmospheres and better understand conditions on Mars and the moon. The discovery provided new pathways for examining both Earth's ancient history and today's environmental conditions.
According to the American Philosophical Society, Dr. Thiemens' work has yielded "fundamental knowledge of planetary change and novel tools for tracing modern global pollutants" by bridging modern environmental research with Earth's deep history.
But, long before becoming one of the world's leading atmospheric chemists and geochemists, Dr. Thiemens was a graduate student. Looking back on that experience, he credits Old Dominion University with preparing him for a career in scientific research.
"In making the transition from undergraduate to graduate studies, the courses were more advanced, and I enjoyed taking them," he said. "I was also able to get sea time on several ships during my time there, and that prepared me for fieldwork that I have done extensively throughout my career."
That preparation led to research around the world, including launching rockets from White Sands Missile Range, conducting climate studies at the South Pole and Greenland Summit and traveling across Tibet, including near Mount Everest, to examine the atmosphere and glaciers.
His connection to Old Dominion University began even earlier. As a high school student in nearby Churchland, Virginia, Dr. Thiemens sought guidance from Professor Jacques Zaneveld, Ph.D., who was Chair of the Biology Department and founder of the Department of Oceanography, whose mentorship helped shape his academic path.
"As a first-generation college student, his advice on what courses I should take and what they would prepare me for made a tremendous difference," Dr. Thiemens said.
The significance of Dr. Thiemens' work spans well beyond the laboratory. Scientists continue to use isotope-based techniques to study climate change, air quality, environmental resilience and global processes. The methods developed through his research continue to be essential to understanding how Earth's systems have evolved and how they may continue to change.
His career also illustrates the lasting value of curiosity-driven research and the impact of a strong academic foundation. For Old Dominion University, his achievements demonstrate how graduate education and faculty mentorship can prepare students to make discoveries that influence scientific understanding on a global scale.
His career serves as an example for all Monarchs of where intellectual curiosity, rigorous research and academic opportunity can lead.
"Simply decide what you really enjoy the most," Dr. Thiemens said. "One always does the best at what you are happy with and that motivates you."
What began with graduate studies in oceanography at Old Dominion University ultimately led to a defining moment and significant discovery that drastically changed how scientists study Earth, climate and the solar system. Decades later, researchers around the world continue to build on that work, using Dr. Thiemens’ insights to better understand our planet, explore others and address some of humanity's most complex challenges.