Our group uses the distribution and stable isotopic composition of biologically-produced organic molecules that accumulate in the environment to study climatic and ecological changes in the recent geologic past, and to determine how human activities influence these systems today. We make particular use of compound-specific hydrogen isotope ratios of lipid biomarkers. The large natural variability in these lipid hydrogen isotope ratios facilitates their use as proxies for diverse processes, and they encode information about climate, ecology, and metabolism. We work to improve our mechanistic understanding of the controls on the stable isotope distribution of biomarkers and other organic geological proxies, and apply these tools to answer questions about past changes and modern carbon cycling. 

New paper:Central European Hydroclimate Since the Younger Dryas Inferred from Vegetation‐Corrected Sedimentary Plant Wax δ²H Values

Plant wax hydrogen isotopes are an important and commonly used tool for reconstructing past hydroclimate from lake sediments. However, the isotopic composition of waxes can be impacted by both changing climate and changing vegetation sources. In this study, led by Organic Geochemistry PhD student Ricardo Santos, and recently published in Paleoceanography and Paleoclimatology, we tested different methods to correct sedimentary plant wax hydrogen isotope values for changes in vegetation source. We showed that in central Europe, a simple correction using the relative abundance of different plant waxes allows us to isolate changes in past precipitation hydrogen isotopes. This approach will facilitate improved reconstructions of past hydroclimate change from lake sediments throughout Europe. 

Link zur Publikation: https://doi.org/10.1029/2025PA005401

New SNSF project funded: Investigating the ecological and climatic conditions at ice age refugia to assess past and future ecosystem functioning (ECO-ICE)

How did Europe's temperate forests survive the harshest climatic period of the last Ice Age? Where were the last refuges of temperate flora when ice sheets covered much of the continent? What can these ancient survival strategies teach us about the future of ecosystems under rapid climate change? We will use lake sediments to investigate these questions in collaboration with Oliver Heiri (Uni Basel), Willy Tinner (Uni Bern), and Christoph Schwörer (Uni Bern) as part of a project newly funded by SNSF. There are eight open PhD positions among the four research groups. If you are interested in joining our organic geochemistry group and reconstructing climate during the last ice age, please find more information and submit your application by 21. April here: 

https://jobs.unibas.ch/offene-stellen/phd-position-in-organic-geochemistry-and-paleolimnology/5c07e402-3a07-4c05-975b-9c9a1700e598

Congratulations to Dr. Antonia Klatt! On 18. March, 2026, Antonia Klatt successfully defended her PhD thesis, entitled “Biogeochemical proxies for the reconstruction of past phytoplankton community dynamics.” During her studies, Antonia applied diverse techniques across timescales. She developed a lipid-based framework to track the relative abundance of cyanobacteria using modern lake water samples, and tested and cross-compared this approach with sedimentary DNA in short sediment cores from lakes that have experience major ecological change due to human activities in the 20^th century. Finally, she reconstructed algal community dynamics over the past ~13,000 years in Rotsee, Switzerland, using lipid biomarkers, stable isotopes, and pigments, and showed how warming temperatures in the early Holocene likely promoted cyanobacteria populations in the past. Antonia is moving on to a postdoctoral research position at the University of Stockholm, and we wish her all the best in the years to come!