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 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 PhD positions among the four research groups. 

New paper: Precipitation Intensity Increased Across the South Pacific Convergence Zone in the Industrial Age

Precipitation patterns in the tropical Pacific are not only important for local communities and ecosystems, but also have far-reaching implications for the global climate system. Using sediment cores from freshwater lakes in the Solomon Islands and Vanuatu, we were able to demonstrate that a trend towards wetter conditions has been observed in this region over the past few centuries. This contrasts with climate model predictions regarding the effects of global warming and helps us to identify the implications of some likely biases in the model simulations of the climate in the tropical Pacific.

Link zum Artikel: https://doi.org/10.1029/2026GL122187

Welcome Shannon and Andrea! Shannon Dyer and Andrea Karen joined the Organic Geochemistry group on 1 July 2026. They will both complete PhD projects focused on reconstructing climate in central Europe and the Mediterranean during the last ice age, within the framework of the broader ECO-ICE project. We are looking forward to working with them over the coming years!

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

Hydrogen isotopes in plant waxes are an important and widely used tool for reconstructing past hydroclimates from lake sediments. However, the isotopic composition of the waxes can be influenced by both climate changes and changes in vegetation. In this study, led by Ricardo Santos, a PhD student in Organic Geochemistry, and recently published in *Paleoceanography and Paleoclimatology*, we tested various methods for correcting hydrogen isotope values of plant waxes in sediments to account for vegetation composition. We were able to demonstrate that, in Central Europe, a simple correction based on the relative abundance of different plant waxes makes it possible to isolate past changes in hydrogen isotopes in precipitation. This approach will facilitate improved reconstructions of past hydroclimatic changes using lake sediments across Europe.

Link to the publication: https://doi.org/10.1029/2025PA005401