Project Details
Projekt
Climate change impacts on ocean nitrogen cycling during the Paleogene-Eocene Thermal Maximum
Applicant
Dr. Felix Elling
Subject Area
Palaeontology
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 527682349
Global climate change caused by anthropogenic emissions of CO2 and other greenhouse gases represents a challenge to the health of ocean ecosystems, not only due to warming but also due to secondary effects such as ocean acidification and deoxygenation. These secondary effects influence the operation of ocean biogeochemical cycles that sustain oceanic food webs. Specifically, the biogeochemical cycling of the essential nutrient nitrogen is sensitive to ocean warming, acidification, and deoxygenation. Changes to these parameters are thought to result in adjustments to the bioavailability of nitrogen through changes in the rates of input (nitrogen fixation), internal recycling (nitrification), and output (nitrogen loss). While changes in ocean nitrogen cycling have been observed as a result of ~1 °C warming over the last decades, little is known how the nitrogen cycle will change under warmer-than-present conditions. Here, I propose to study a paleoclimate analog of modern climate change, the Paleocene-Eocene Thermal Maximum (PETM, 55.8 million years ago), to assess long-term climate change impacts on the marine nitrogen cycle and food webs. The PETM was a 200.000-year interval of global ocean warming (~6 °C), deoxygenation and acidification. To generate new insights into the functioning of the nitrogen cycle under warmer-than-present climate, we will use the nitrogen stable isotopic composition of foraminifera, bulk sediment, and chlorophyll derivatives to assess changes in nitrogen fixation and nitrogen loss. Additionally, we will use biomarkers to semi-quantitatively reconstruct changes in specific nitrogen cycle processes such as nitrification and nitrogen loss, as well as biomarkers and fossil fish teeth that can yield insights into ecological changes in the ocean food web. Regional differences and the timing relative to warming, ocean acidification, and deoxygenation will be studied to understand the environmental constraints on, and timescales of, changes in nitrogen cycling. Finally, we will use numerical computer models to verify and quantify changes in nitrogen cycle fluxes and their effects on ocean food webs. The outcomes of this project will lead to a better understanding of the long-term future of the nitrogen cycle under warmer-than-present climate.
DFG Programme
Infrastructure Priority Programmes
International Connection
United Kingdom, USA
Co-Investigators
Dr. Kevin Becker; Professorin Dr. Julia Gottschalk; Alfredo Martinez-Garcia, Ph.D.
Cooperation Partners
Professorin Dr. Fanny Monteiro; Professorin Dr. Ann Pearson; Dr. Elizabeth Sibert
