M.Sc. Manuel Ehnis

About:
I am a PhD student in the Past Ocean Dynamics group at Heidelberg University, supervised by Dr. Jörg Lippold. My research focuses on how changes in ocean circulation have influenced marine productivity and the ocean’s ability to store carbon over thousands of years. I study deep-sea sediments from sensitive regions of the Atlantic Ocean, to investigate how variations in the Atlantic Overturning Circulation have impacted the global carbon cycle. By understanding these past dynamics, my work aims to improve predictions of how the ocean will respond to ongoing and future climate change.


Research Focus:
- Ocean Dynamics and palaeoclimatology
- Analysis of deep-sea sediments
- Bioproductivity and export production (biogenic opal, TOC, Ba_bio)
- Radiogenic tracers (U/Th, ²³¹Pa/²³⁰Th, εNd)


Short CV:

since 2025         PhD candidate in the research group for Past Ocean Dynamics (Heidelberg
                               University)
                               DFG-funded project “Reconstructing the long- and short-term variability of the
                               export production in the Atlantic Ocean”

2022-2025         Master Earth Sciences (Heidelberg University)
                               Thesis: Neodymium Cycling and Water Mass Structure in the Indian Sector of the 
                               Southern Ocean
                               Cooperation with GEOMAR Kiel

2020-2025         Student research assistant
                               Research Group Past Ocean Dynamics
                               Research Group Sedimentology and Paleoclimatology

2024                     Exchange scientist (Kyoto University, JP)
                                Five-week research visit within the DAAD project “A novel carbon cycle model 
                               based on molecular mechanisms of  biological methane emission and 
                               consumption”

2023                     Shipboard scientist
                                Antarctic Expedition PS140 (EASI-2) aboard RV Polarstern
                               Seawater sampling for neodymium isotope analysis to assess water mass  
                               structure and mixing

2019-2022         Bachelor Earth Sciences (Heidelberg University)
                               Thesis: Wet chemical opal analysis in marine sediments
                               Heinz Friedrich Schöler – Umweltpreis Graduation Award (best Thesis)

Conference contributions:

Gutjahr, M., Huang, H., Menzel, D., Ehnis, M., Rickli, J., Hu, J., Pöppelmeier, F., Lippold, J., Frank, M., Creac’h, L., Kreps, G., Oetjens, A., Rieke, O., Janout, M., Tippenhauer, S., Herraiz-Borreguero, L. (2025): East Antarctic neodymium supply to the Indian sector of the Southern Ocean and its dispersal into the open Southern Ocean. Goldschmidt 2025.

Lippold, J., Ehnis, M., Süfke, F., Tautenhahn, S., Valk, O., Blaser, P., Pöppelmeier, F., Regelous, M. (2023): Holocene Variability of the AMOC as derived from ²³¹Pa/²³⁰Th. Goldschmidt 2023.