Climate & Earth Surface Geochemistry Group
Lamont-Doherty Earth Observatory
Columbia University
Principal Investigator
Sarah is an Assistant Professor in the Department of Earth and Environmental Sciences at Columbia University. Her research focuses on understanding and tracking Earth surface processes in a variety of environments, on both geologic timescales and in the modern. Born and raised in Alaska, she received her PhD in Geology from University of Michigan in 2016. She held a University of California Chancellor’s Postdoctoral Fellowship at UC Irvine, followed by a Ford Foundation Postdoctoral Fellowship at the University of Chicago. She joined the faculty at Scripps Institution of Oceanography at UC San Diego in 2019, and moved to Columbia in 2026.
CV sarah.aarons@ldeo.columbia.edu
Current Team
PhD Student
CV ac6202@columbia.edu
Alissa received a B.S in Geology and Geophysics, and Chemistry from the University of Wisconsin Madison. Alissa is interested in the intersection of geology and chemistry to better understand past climate and warm intervals throughout Earth history. Alissa is studying the isotopic composition of dust in ice cores from Antarctica as a "fingerprint" of its provenance as a proxy for past ice sheet extent and atmospheric circulation. Outside of the lab, Alissa enjoys theatre and documentary filmmaking!
PhD Student
CV jh5275@columbia.edu
Justin studies the marine cycling of zirconium stable isotopes and their potential as tracers of particle scavenging and water mass in the ocean. Before coming to Lamont, Justin earned his BS and MS at Scripps Institution of Oceanography, where his thesis examined Zr stable isotope behavior in rivers and estuaries.
Staff Research Assistant
CV glbrown@ldeo.columbia.edu
Gina graduated from Barnard College in 2026 with a BA in Environmental Biology, and is originally from Massachusetts. She is currently working on a provenance analysis of deglacial sediment from the Bermuda Rise through K/Ar and Nd measurements, which was also her senior thesis. Gina is broadly interested in paleoclimate, paleoceanography, and isotope geochemistry. Outside of the lab, she enjoys rock climbing, hiking, knitting, and ballet. She is also passionate about environmental justice and volunteering in her community.
PhD Student
CV ac6202@columbia.edu
Alissa received a B.S in Geology and Geophysics, and Chemistry from the University of Wisconsin Madison. Alissa is interested in the intersection of geology and chemistry to better understand past climate and warm intervals throughout Earth history. Alissa is studying the isotopic composition of dust in ice cores from Antarctica as a "fingerprint" of its provenance as a proxy for past ice sheet extent and atmospheric circulation. Outside of the lab, Alissa enjoys theatre and documentary filmmaking!
PhD Student
CV jh5275@columbia.edu
Justin studies the marine cycling of zirconium stable isotopes and their potential as tracers of particle scavenging and water mass in the ocean. Before coming to Lamont, Justin earned his BS and MS at Scripps Institution of Oceanography, where his thesis examined Zr stable isotope behavior in rivers and estuaries.
Staff Research Assistant
CV glbrown@ldeo.columbia.edu
Gina graduated from Barnard College in 2026 with a BA in Environmental Biology, and is originally from Massachusetts. She is currently working on a provenance analysis of deglacial sediment from the Bermuda Rise through K/Ar and Nd measurements, which was also her senior thesis. Gina is broadly interested in paleoclimate, paleoceanography, and isotope geochemistry. Outside of the lab, she enjoys rock climbing, hiking, knitting, and ballet. She is also passionate about environmental justice and volunteering in her community.
Lab Alumni
PhD Student, Research Associate (2019-2026)
Linqing developed a new method for purifying and measuring stable zirconium isotopes in seawater. After receiving her PhD from Scripps Institution of Oceanography, she was a postdoctoral researcher under Dr. Alex Halliday at Lamont-Doherty Earth Observatory. Now at ETH Zurich.
Lab Manager, Research Associate (2023-2026)
Eric is an isotope geochemist specializing in redox-sensitive trace metal cycling across modern and ancient Earth systems. His research integrates high-precision isotopic measurements, laboratory experiments, and field observations to develop and apply geochemical proxies for reconstructing ocean and climate evolution. Now at Université de Bretagne Occidentale.
PhD Student (2020-2025)
Austin investigated the chemistry, geometry, and concentration of mineral dust trapped in polar ice. The overarching goal his research is to advance our understanding of the role of dust as both a recorder and catalyst of past climate changes. Now a postdoc at Princeton University.
BS/MS Student (2022-2025)
Anusha is interested in how geological techniques can be leveraged as tools for interdisciplinary research. She worked on creating a geochemical signature for Allan Hills, Antarctica to use in future potential source area apportionment for paleoclimate research. In her master’s thesis she explored the health impacts of wildfire particulate matter over metal rich soils in California. Now a PhD student at the University of St Andrews researching groundwater dynamics in Antarctica.
MS Student, Staff Research Assistant (2023-2026)
Emma’s MS thesis researched the use of non-traditional stable isotope systems, specifically titanium, to differentiate between rock formation processes within island arc settings. She has also assisted with various research projects within the lab, developing a wide skillset of instrumentation and methodology. Now a PhD student at the University of St. Andrews measuring boron isotopes in brachiopod fossils to be used as a proxy for Earth's greenhouse gases throughout the geologic record.
PhD Student (2020-2025)
Emmet is interested in the interaction between processes on the Earth’s surface, such as the transport and fate of mineral dust, and human societies. He primarily uses isotopic source apportionment techniques to characterize the sources of natural and anthropogenically emitted PM and understand their effect on climate, air quality, and bioavailable nutrients. Now a postdoc at the Université de Montréal.
Postdoctoral Researcher (2021-2023)
Kiefer is a marine chemist working on questions regarding the biogeochemical cycling of bioactive trace metals and their role as limiting nutrients for primary producers in the modern ocean. He uses novel geochemical and microbial techniques to explore factors which affect the fate of glacial weathering inputs of bio-essential trace elements, such as iron. Now a postdoc at University of Southern California.
BS/MS Student (2020-2022)