A5058162134- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Geological Studies and Exploration
- Hydrocarbon exploration and reservoir analysis
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Geological and Geophysical Studies
- Paleontology and Stratigraphy of Fossils
- Geological formations and processes
- Geological and Geochemical Analysis
- Marine Biology and Ecology Research
- Cryospheric studies and observations
- Radioactive element chemistry and processing
- Ocean Acidification Effects and Responses
- Pleistocene-Era Hominins and Archaeology
- Geophysics and Gravity Measurements
- Marine and environmental studies
- Nuclear Physics and Applications
- Geochemistry and Geologic Mapping
- Protist diversity and phylogeny
- Aeolian processes and effects
- Geomagnetism and Paleomagnetism Studies
- Atmospheric and Environmental Gas Dynamics
- Radioactive contamination and transfer
- Polar Research and Ecology
Middlebury College
2022-2024
Brown University
2019-2022
Columbia University
2016-2021
Lamont-Doherty Earth Observatory
2014-2021
John Brown University
2021
Providence College
2020
Abstract Abrupt climate changes in the past have been attributed to variations Atlantic Meridional Overturning Circulation (AMOC) strength. However, exact timing and magnitude of AMOC shifts remain elusive, which continues limit our understanding driving mechanisms such variability. Here we show a consistent signal 231 Pa/ 230 Th proxy that reveals spatially coherent picture western circulation over last deglaciation, during abrupt millennial-scale transitions. At onset observe an early...
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...
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. A growing body of observations has revealed rapid changes in both the total inventory and distribution marine oxygen over latter half 20th century, leading to increased interest extending oxygenation records into past. The use paleo-oxygen proxies potential extend spatial temporal range current records, constrain pre-anthropogenic baselines, provide datasets necessary test climate models under different boundary conditions, ultimately understand how ocean responds beyond...
Abstract The equatorial Pacific traverses a number of productivity regimes, from the highly productive coastal upwelling along Peru to near gyre‐like lows international dateline, making it an ideal target for investigating how biogeochemical systems respond changing oceanographic conditions over time. However, conflicting reconstructions during periods rapid climate change, like last deglaciation, render spatiotemporal response ambiguous. In this study, surface since glacial period (30,000...
El Niño events, the warm phase of Niño-Southern Oscillation (ENSO) phenomenon, amplify climate variability throughout world
As the largest reservoir of carbon exchanging with atmosphere on glacial-interglacial timescales, deep ocean has been implicated as likely location sequestration during Pleistocene glaciations. Despite strong theoretical underpinning for this expectation, radiocarbon data watermass ventilation ages conflict, and proxy interpretations disagree about depth, origin even existence respired pool. Because any change in storage respiratory is accompanied by corresponding changes dissolved oxygen...
Abstract The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in balance heat between hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation. Although ITCZ thought experience largest shifts during deglacial stadial events, magnitude proven difficult reconstruct, part because a paucity high-resolution records, particularly those including spatial components. Here we track from 150 110 ka at three sites central equatorial...
Abstract. A growing body of observations reveals rapid changes in both the total inventory and distribution marine oxygen over later half 21st century, leading to increased interest extending oxygenation records into past. Use paleo-oxygen proxies have potential extend spatial temporal range current records, bound pre-anthropogenic baselines, provide datasets necessary test climate models under different boundary conditions, ultimately understand how ocean responds beyond decadal scale...
Abstract Much uncertainty exists about the state of oceanic and atmospheric circulation in tropical Pacific over last glacial cycle. Studies have been hampered by fact that sediment cores suitable for study were concentrated western eastern parts Pacific, with little information from central Pacific. Here we present a suite collected Line Islands Ridge which show sedimentation rates stratigraphies paleoceanographic investigations. Based on radiocarbon oxygen isotope measurements planktonic...
Quantitative records of bottom water oxygen (BWO) are critical for understanding deep ocean change through time. Because the stoichiometric relationship between and carbon, BWO provide insight into physical biogeochemical processes that control air-sea partitioning both gases over Quaternary glacial-interglacial cycles with important implications climate benthic habitats. Here, we present new geochemical datasets from Ocean Discovery Program (ODP) Site 1240 in eastern equatorial Pacific to...
Abstract. The equatorial Pacific is a nexus of key oceanic and atmospheric phenomena, its regional climate has critical implications for hydroclimate, the partitioning CO2, temperature on global scale. spatial complexity signals across basin long posed challenge interpreting interplay different phenomena including changes in Intertropical Convergence Zone (ITCZ) El Niño–Southern Oscillation (ENSO). Here, we present new, millennially resolved sediment core chronologies stable isotope records...
Abstract Merging the late Quaternary Arctic paleoceanography into Earth's global climate history remains challenging due to lack of robust marine chronostratigraphies. Over ridges notably, low and variable sedimentation rates, scarce biogenic ensuing from productivity and/or poor preservation, oxygen isotope paleomagnetic records differing stacks represent major impediments. However, as illustrate here based on consistent Mendeleev‐Alpha Lomonosov Ridges, disequilibria between U‐series...
Earth and Space Science Open Archive This work has been accepted for publication in Global Biogeochemical Cycles. Version of RecordESSOAr is a venue early communication or feedback before peer review. Data may be preliminary. Learn more about preprints. preprintOpen AccessYou are viewing the latest version by default [v1]Global Ocean Sediment Composition Burial Flux Deep SeaAuthorsChristopherHayesiDKassandra MCostaRobert FAndersonEvaCalvoiDZannaChaseiDLudmila...
Abstract Understanding how the Intertropical Convergence Zone (ITCZ) responds to abrupt climate change is essential for reconstructing large‐scale atmospheric circulation across transitions. However, key differences between dynamical models and observational constraints on ITCZ movement remain unresolved. Here, we examine Pb Nd radiogenic isotope signatures of dust deposited in central equatorial Pacific (CEP) from 160 105 kyr. We quantified relative contributions Northern Hemisphere‐...
Oxygen is essential for marine ecosystems, and it linked by respiration to carbon storage in the deep ocean. Reconstructing oxygen concentrations past has been limited absence of quantitative, rather than qualitative, proxies, but several new (semi-) quantitative proxies have recently developed. In this study we explore possibility adding bulk sedimentary uranium (U) list normalizing barium (Ba). First, U/Ba bottom water are compared on a global scale, using core top database, pelagic...