Martin Wahlen, a professor of physics at Scripps Institution of Oceanography, UC San Diego, retired June 30 following 19 years of service.
Wahlen’s research career focused on the study of atmospheric trace gases, their global budgets in the present atmosphere, and their roles in past climate changes as determined from studies of air entrapped in ice cores from Greenland and Antarctica. He has done important work on the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). He is particularly known for his expertise in the difficult measurement of variations in the isotopic composition of these gases, despite their low abundances in air that range down to parts-per-million to parts-per-trillion levels.
His work on isotopes of CO2 in the modern atmosphere, together with late Scripps geochemist Charles David Keeling, has led to a better understanding of global carbon cycle budgets. His work on Antarctic ice cores has focused on the relationships between changes in CO2 and changes in climate spanning 500,000 years of Earth history and at least five glacial-interglacial cycles.
Wahlen is well-regarded as a mentor to graduate and undergraduate students, and he has been an active participant in UCSD’s Faculty Mentor Program. As a UCSD undergraduate student, Laurent Palmatier studied nitrous oxide levels in the troposphere with Wahlen and described him as “the exact kind of person you want as your faculty mentor. For me, he has been a mentor, not just on our research project, but on important life issues that I’ve had as well,” Palmatier said.
Wahlen received both his master’s and Ph.D. from the University of Bern in Switzerland. He served for a brief time in the UCSD Department of Chemistry beginning in 1970 before returning to Bern as a senior research associate. After serving as an associate professor at the State University of New York at Albany, Wahlen returned to UCSD in 1990 to join Scripps as a professor.