A5058641429- Geology and Paleoclimatology Research
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Geological formations and processes
- Hydrocarbon exploration and reservoir analysis
- Marine and coastal ecosystems
- Paleontology and Stratigraphy of Fossils
- Geochemistry and Elemental Analysis
- Geological and Geophysical Studies
- Geological Studies and Exploration
- Pleistocene-Era Hominins and Archaeology
- Radioactive contamination and transfer
- Offshore Engineering and Technologies
- Marine and environmental studies
- Archaeology and ancient environmental studies
- Radioactive element chemistry and processing
- Marine Biology and Ecology Research
- Geological and Geochemical Analysis
- Atmospheric and Environmental Gas Dynamics
- Nuclear Physics and Applications
- Geochemistry and Geologic Mapping
- Oceanographic and Atmospheric Processes
- Mineralogy and Gemology Studies
- Ocean Acidification Effects and Responses
- Geomagnetism and Paleomagnetism Studies
Heidelberg University
2016-2025
University of Bern
2014-2023
Oeschger Centre for Climate Change Research
2014-2018
Heidelberg University
2018
Heidelberg Academy of Sciences and Humanities
2007-2012
Abstract Quantitative knowledge about the burial of sedimentary components at seafloor has wide‐ranging implications in ocean science, from global climate to continental weathering. The use 230 Th‐normalized fluxes reduces uncertainties that many prior studies faced by accounting for effects sediment redistribution bottom currents and minimizing impact age model uncertainty. Here we employ a recently compiled data set with an updated database surface composition derive atlases deep‐sea flux...
Uncertainties persist in the understanding of Atlantic meridional overturning circulation and its response to external perturbations such as freshwater or radiative forcing. Abrupt reduction is considered a climate tipping point that may have been crossed when Earth's was propelled out last ice age. However, evolution since Last Glacial Maximum (22-18 thousand years ago) remains insufficiently constrained due model proxy limitations. Here we leverage information from both compilation records...
Abstract Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid in atmospheric CO 2 that remain unexplained. While role of Southern Ocean as a 'control valve' on ocean–atmosphere exchange has been emphasized, exact nature this role, particular relative contributions physical (for example, ocean dynamics air–sea gas exchange) versus biological processes export productivity), remains poorly constrained. Here we combine reconstructions...
Ocean circulation may have undergone reductions and reinvigorations in the past closely tied to regional climate changes. Measurements of 231 Pa/ 230 Th ratios a sediment core from Bermuda Rise been interpreted as evidence that Atlantic Meridional Overturning Circulation (AMOC) was weakened or completely eliminated during period catastrophic iceberg discharges (Heinrich‐Event 1, H1). Here we present new data show further peaks Heinrich‐2 (H2) Heinrich‐3 (H3). Additionally, tight correlation...
Abstract Changes in heat transport associated with fluctuations the strength of Atlantic meridional overturning circulation (AMOC) are widely considered to affect position Intertropical Convergence Zone (ITCZ), but temporal immediacy this teleconnection has date not been resolved. Based on a high‐resolution marine sediment sequence over last deglaciation, we provide evidence for synchronous and near‐linear link between changes interhemispheric sea surface temperature difference continental...
Abstract 230 Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, nuances of systematics, with regard particle type, size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records from across global ocean at two time slices, Holocene (0–5,000 years...
Abstract There is a converging body of evidence supporting measurable slowdown the Atlantic Meridional Overturning Circulation (AMOC) as climate warms and Northern Hemisphere ice sheets inexorably shrink. Within this context, we assess variability AMOC during Holocene based on marine sediment core retrieved from deep northwest Atlantic, which sensitively recorded large‐scale deglacial transitions in water circulation. While there diffuse notion Labrador Nordic Seas overturning, report...
We use the Bern3D model of intermediate complexity to examine marine cycle isotopes 231Pa and 230Th relationship between particle-bound ratio Pap/Thp changes in formation North Atlantic Deep Water (NADW). Model parameters describing reversible scavenging by organic particles, opal, calcite resuspended sediments were systematically varied alternative sink parametrisations explored. It proves difficult simultaneously achieve a good agreement with observations dissolved particle-associated...
Proxy reconstructions from deep ocean sediments have helped to shape our understanding of the role global overturning circulation in past climate change. Neodymium (Nd) isotopes contributed this knowledge, as a tracer bottom water provenance and mixing. Here, we extend implementation Nd physical-biogeochemical Bern3D model by revising number critical parameterizations, which result an improved description marine cycle. We exploit dynamically consistent framework model, allows us assess...
The Atlantic Meridional Overturning Circulation (AMOC) plays an important role in the Northern Hemisphere climate system. Significant interest went into question of how excessive freshwater input through melting continental ice can affect its overturning vigor and, hence, heat supply, to higher northern latitudes. Such forcing be tested by investigating behavior during extreme iceberg discharge events open North last glacial period, so‐called Heinrich (HE). Here we present neodymium (Nd)...
ABSTRACT Radiocarbon ( 14 C) measurements of foraminifera often provide the only absolute age constraints in marine sediments. However, they are challenging as their reliability and accuracy can be compromised by reduced availability adequate sample material. New analytical advances using MIni CArbon DAting System (MICADAS) allow C dating very small samples, circumventing size limitations inherent to conventional with accelerator mass spectrometry (AMS). Here we use foraminiferal samples...
Abstract Increased carbon sequestration in the ocean subsurface is commonly assumed to have been one of main causes responsible for lower glacial atmospheric CO2 concentrations. Remineralized must stored away from atmosphere thousands years, yet water mass structure accommodating such increased storage continues be debated. Here, we present new sediment-derived bottom-water neodymium isotope records that allow fingerprinting masses and provide a more complete picture Atlantic Meridional...
Abstract Negative stable carbon isotopic excursions have been observed throughout most of the mid‐depth (~1000–3000 m) Atlantic Ocean during Heinrich Stadial 1 (HS1) and Younger Dryas (YD). Although there is an agreement that these were in some way associated with a slowdown Meridional Overturning Circulation (AMOC), still no consensus on precise mechanism(s). Here we present benthic oxygen (δ 13 C δ 18 O) records from five cores western equatorial (WEA). Together published nearby cores,...
[1] Variations of the Atlantic Meridional Overturning Circulation (AMOC) are believed to have crucially influenced Earth's climate due its key role in inter-hemispheric redistribution heat and carbon. To assess past strength, sedimentary 231Pa/230Th proxy has been developed improved but also contested sensitivity other factors beyond ocean circulation. In order provide a better basis for understanding system, therefore shed light on controversy, we compare new measurements Holocene sediments...
Due to the major role played by diatoms in marine biological pump, opal/biogenic silica (bSi) has a strong potential as proxy for paleoproduction reconstructions. Here, we present detailed evaluation of independent Fourier transform infrared spectroscopy (FTIRS) calibration introduced Meyer-Jacob et al. (2014a), which is based on synthetic sediment mixtures with known concentrations bSi and application partial least squares (PLS) regression, determination sediments. To test robustness FTIRS...
Abstract. Thanks to its optimal location on the northern Brazilian margin, core MD09-3257 records both ocean circulation and atmospheric changes. The latter occur locally in form of increased rainfall adjacent continent during cold intervals recorded Greenland ice North Atlantic sediment cores (i.e., stadials). These events are as peaks ln(Ti ∕ Ca). New sedimentary Pa Th data indicate that mid-depth western equatorial water mass transport decreased all stadials last 40 kyr. Using...