Ellen Thomas

Ellen Thomas
Yale University | YU · Department of Geology and Geophysics

PhD, University of Utrecht, Netherlands

About

356
Publications
74,018
Reads
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25,169
Citations
Introduction
Research focused on benthic foraminifera, from coastal salt marshes to the deep sea, from living to late Ctetaceous.
Additional affiliations
January 2013 - present
University of Bristol
Position
  • Leverhulme Visiting Professor
January 2000 - present
Wesleyan University
Description
  • Research professor
October 1992 - present
Yale University
Position
  • Senior Researcher

Publications

Publications (356)
Article
Long-term climatic trends of the Paleogene were interrupted by global perturbations of the carbon cycle, commonly associated with warming of surface and bottom waters and ecosystem disturbance. Most of these perturbations occurred in the Paleocene - Eocene greenhouse climate, but others were superimposed on the transition of greenhouse-to- icehouse...
Article
Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and iodine to calcium ratio (I/Ca, higher I/Ca: higher oxygenation) are both promising paleoceanographic proxies that will advance through testing in down-core studies. Here we report the first down-core comparison (~45...
Article
Full-text available
The Paleogene was punctuated by perturbations of the global carbon cycle, many associated with transient global warming events (hyperthermals). The Dan-C2 event (~160 kyr after Cretaceous/Paleogene boundary; K/Pg) was the oldest of these eccentricity-linked carbon cycle disturbances (ELCD). In contrast to other hyperthermals, the Dan-C2 event was n...
Article
Under stress, corals and foraminifera may eject or consume their algal symbionts (“bleach”), which can increase mortality. How bleaching relates to species viability over warming events is of great interest given current global warming. We use size-specific isotope analyses and abundance counts to examine photosymbiosis and population dynamics of p...
Article
Full-text available
All studies focused on the evaluation of paleoecological variability over geological time must be linked to a specific age or time interval, which can be defined using different time scales (biostratigraphic, chronostratigraphic, geochronological or orbital). Therefore, integrated time scales are essential to allow comparisons of data from differen...
Article
Full-text available
Benthic foraminifera are the most common meiofaunal unicellular deep-sea biota, forming skeletons used as proxies for past climate change. We aim to increase understanding of past non-analog oceans and ecosystems by evaluating deep-sea benthic foraminiferal responses to global environmental changes over latest Cretaceous through Oligocene times (67...
Book
How oxygen levels in Earth’s atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous tracers to tackle this question, utilizing geochemical characteristics of different elements. Iodine incorporated in calcium carbonate (including biogenic) minerals, reported as I/Ca, is a proxy...
Article
Full-text available
Falling atmospheric CO2 levels led to cooling through the Eocene and the expansion of Antarctic ice sheets close to their modern size near the beginning of the Oligocene, a period of poorly documented climate. Here, we present a record of climate evolution across the entire Oligocene (33.9 to 23.0 Ma) based on TEX86 sea surface temperature (SST) es...
Article
Full-text available
We reconstruct sea surface temperatures (SSTs) at Deep Sea Drilling Project Site 608 (42.836°N, 23.087°), north of the Azores Front, and Ocean Drilling Program Site 982 (57.516°N, 15.866°), under the North Atlantic Current, in order to track Miocene (23.1–5.3 Ma) development of North Atlantic surface waters. Mean annual SSTs from TEX86 and UK′37 pr...
Article
The decline in dissolved oxygen in global oceans (ocean deoxygenation) is a potential consequence of global warming which may have important impacts on ocean biogeochemistry and marine ecosystems. Current climate models do not agree on the trajectory of future deoxygenation on different timescales, in part due to uncertainties in the complex, linke...
Article
The cause of the end-Cretaceous mass extinction is vigorously debated, owing to the occurrence of a very large bolide impact and flood basalt volcanism near the boundary. Disentangling their relative importance is complicated by uncertainty regarding kill mechanisms and the relative timing of volcanogenic outgassing, impact, and extinction. We used...
Article
Full-text available
Mass extinction at the Cretaceous-Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here,...
Article
Profound changes in upper ocean oxygenation have taken place in recent decades and are expected to continue in the future, but the complexity of the processes driving these changes has yet to be fully unraveled. Planktic foraminiferal I/Ca is a promising tool to reconstruct the extent of past upper ocean oxygenation, but a thorough assessment is ne...
Article
Full-text available
Our understanding of the long‐term evolution of the Earth system is based on the assumption that terrestrial weathering rates should respond to, and hence help regulate, atmospheric CO2 and climate. Increased terrestrial weathering requires increased carbonate accumulation in marine sediments, which in turn is expected to result in a long‐term deep...
Article
Full-text available
Climate change is predicted to alter temperature, carbonate chemistry and oxygen availability in the oceans, which will affect individuals, populations and ecosystems. We use the fossil record of benthic foraminifers to assess developmental impacts in response to environmental changes during the Palaeocene–Eocene Thermal Maximum (PETM). Using an un...
Article
Full-text available
We combine stable isotope, calcareous nannoplankton, and benthic foraminiferal records for Ocean Drilling Program Sites 1262 (paleodepth ~3,500 m) and 1263 (paleodepth ~1,500 m) on Walvis Ridge (SE Atlantic), to document the marine biotic response to Eocene Thermal Maximum 3, in the early part of the Early Eocene Climate Optimum, ~3.1 Myr after the...
Article
Full-text available
Rising oceanic and atmospheric oxygen levels through time have been crucial to enhanced habitability of surface Earth environments. Few redox proxies can track secular variations in dissolved oxygen concentrations ([O2]) around threshold levels for metazoan survival in the upper ocean. We present an extensive compilation of iodine to calcium ratios...
Article
Climate proxies indicate coupling between changes in atmospheric pCO2, global temperatures, and ice volume over much of the Cenozoic. Evidence has been presented for decoupling of these factors in the Miocene, though the cause of the apparent decoupling was uncertain. Here, we revisit Deep Sea Drilling Program (DSDP) Site 608 (24-9 Ma) in the North...
Article
Full-text available
The early Eocene greenhouse world was marked by multiple transient hyperthermal events. The most extreme was the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma), linked to the extinction of the globally recognised deep-sea benthic foraminiferal Velasco fauna, which led to the development of early Eocene assemblages. This turnover has been studied a...
Data
Taxonomic list. Most common benthic foraminifera during the early Eocene and other species mentioned in the text. (DOCX)
Data
Quantitative data of benthic foraminifera in the studied samples from ODP Site 1051 and 1258. (XLSX)
Data
Benthic foraminifera across the middle Ypresian interval. (XLSX)
Data
Number of species vs. number of specimens in samples from ODP Sites 1051 and 1258. (TIF)
Data
Quantitative data of benthic foraminifera in the studied samples from DSDP site 401. (XLSX)
Data
Benthic foraminifera across the lower Ypresian interval. (XLSX)
Data
Quantitative data of benthic foraminifera in the studied samples from ODP Site 1262 and 1263. (XLSX)
Data
Number of samples, specimens and species, and size fraction studied in each site. (XLSX)
Article
The Palaeocene–Eocene Thermal Maximum1, 2 (PETM) was a global warming event that occurred about 56 million years ago, and is commonly thought to have been driven primarily by the destabilization of carbon from surface sedimentary reservoirs such as methane hydrates3. However, it remains controversial whether such reservoirs were indeed the source o...
Article
The temperature of the deep ocean plays a vital role in the Earth’s climate system. Paleo-reconstructions of deep-sea temperatures have traditionally been based on the oxygen isotope composition of deep-sea benthic foraminiferal calcite shells, although this parameter depends upon polar ice volume as well as temperature. More recent reconstructions...
Article
Full-text available
The geological cycling of carbon ties together the ocean-Atmosphere carbon pool, Earth's biosphere, and Earth's sedimentary reservoirs. Perturbations to this coupled system are recorded in the carbon-isotopic (δ¹³C) composition of marine carbonates. Large amplitude δ¹³C excursions are typically treated as individual events and interpreted according...
Article
The Editor-in-Chief of Paleoceanography explains that the journal is changing its name to Paleoceanography and Paleoclimatology to reflect the evolution of science in this field.
Article
A collection of Commentaries published in the journals of the American Geophysical Union illuminate the deep and growing benefits of research in the Earth and space sciences for humanity.
Article
Full-text available
A holistic view of the Bengal–Nicobar Fan system requires sampling the full sedimentary section of the Nicobar Fan, which was achieved for the first time by International Ocean Discovery Program (IODP) Expedition 362 west of North Sumatra. We identified a distinct rise in sediment accumulation rate (SAR) beginning ∼9.5 Ma and reaching 250–350 m/Myr...
Article
Full-text available
Benthic foraminiferal biofacies were delimited for the upper Maastichtian through upper Eocene of five Brazilian marginal basins (Sergipe-Alagoas, Mucuri, Campos, Santos and Pelotas) and two DSDP Sites 356 and 20C of the western South Atlantic. The biofacies were determined based on the benthic foraminiferal assemblages and associated parameters, i...
Article
Newberry Volcano in Oregon, USA, has two small crater lakes inside its caldera: East Lake and Paulina Lake. The 50-80 m deep lakes differ in morphology, water chemistry and sediment composition, although separated only by a narrow volcanic ridge. East Lake is a terminal lake with gaseous geothermal inputs, whereas Paulina Lake has an outlet (Paulin...
Article
Full-text available
Anthropogenic warming could well drive depletion of oceanic oxygen in the future. Important insight into the relationship between de-oxygenation and warming can be gleaned from the geological record, but evidence is limited because few ocean oxygenation records are available for past greenhouse climate conditions. We use I/Ca in benthic foraminifer...
Article
Full-text available
Oxygen depletion in the upper ocean is commonly associated with poor ventilation and storage of respired carbon, potentially linked to atmospheric CO2 levels. Iodine to calcium ratios (I/Ca) in recent planktonic foraminifera suggest that values less than ∼2.5 μmol mol-1 indicate the presence of O2-depleted water. Here we apply this proxy to estimat...
Article
We investigated the response of late Paleocene-middle Eocene (~60-37.5 Ma) benthic foraminiferal assemblages to long term climate change and hyperthermal events including the Paleocene-Eocene Thermal Maximum (PETM) at ODP Site 865 on Allison Guyot, a seamount in the Mid-Pacific Mountains. Seamounts are isolated deep-sea environments where enhanced...
Article
Full-text available
The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene–Eocene Thermal Maximum (PETM) in the central-western Tethys. We combine a new, high-resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental c...
Article
Full-text available
Morphologically uniform, low-trochospiral foraminifera are a common, though not very well-preserved component of foraminiferal assemblages across the interval including the Middle Eocene Climatic Optimum (MECO) at the Alano (northeastern Italy) and Monte Cagnero (central Italy) Tethyan sections. The morphology of these specimens, combined with thei...
Article
Synchrotron powder X-ray diffraction and scanning electron microscopy examinations of manganese oxide concretions/nodules (~0.3–1.0 mm diameter) from ODP Site 1262 on Walvis Ridge in the Southeastern Atlantic Ocean revealed that they consist primarily of the layered Mn oxide phase jianshuiite [(Mg,Mn,Ca)Mn34+O7·3H2O]. The nodules are from an interv...
Conference Paper
Foraminifera are important microfossils used in analysis of paleoclimates and paleoenvironments. Examining their ontogeny (including size of the protoconch) and growth rates can provide insight into their ecology and life history, e.g., food supply in the environments where they lived. In planktic taxa, shifts in habitat (e.g., moving to deeper wat...
Poster
In modern oceans, temperature stress can cause symbiont-bearing taxa, like corals and sponges, to expel their photosymbionts in ‘bleaching’ events that can be lethal. Whether or not symbiotic clades will be able to adapt to elevated temperatures for the coming millennia is hard to predict from empirical observations of living taxa alone. Instead, p...
Article
Full-text available
The response of many organisms to the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) has been documented, but marine mollusks are not known from any deposits of that age. For the first time, we describe a PETM assemblage of pteropods (planktic mollusks), consisting of six species representing three genera ( Altaspiratella, Heliconoides and Limacin...
Article
Antarctic continental-scale glaciation is generally assumed to have initiated at the Eocene-Oligocene Transition, yet its subsequent evolution is poorly constrained. We reconstruct changes in bottom water temperature and global ice volume from 0-17 Ma using δ18O in conjunction with Mg/Ca records of the infaunal benthic foraminifer, O. umbonatus fro...
Article
Full-text available
The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene– Oligocene transition was investigated at a high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic Ocean) and compared with a lowerresolution benthic foraminiferal record. During this time interval, global cli...
Article
Full-text available
N.B. This is the paper under (open) review on Climate of the Past DISCUSSION. The final, fully citable and published version is: Giusberti L., Boscolo Galazzo F., Thomas E., 2016. Variability in climate and productivity during the Paleocene–Eocene Thermal Maximum in the western Tethys (Forada section). Climate of the Past 12(2): 213-240, DOI: 10.51...
Article
Full-text available
Eocene Thermal Maximum 2 (ETM2) occurred ~1.8 Myr after the Paleocene-Eocene Thermal Maximum (PETM) and, like the PETM, was characterized by a negative carbon isotope excursion and warming. We combined benthic foraminiferal and sedimentological records for Southeast Atlantic Sites 1263 (1500 m paleodepth) and 1262 (3600 m paleodepth) to show that b...
Article
Full-text available
The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene–Oligocene transition (~34.8–32.7 Ma) was investigated at high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, South East Atlantic Ocean), and compared with a lower resolution benthic foraminiferal record. During this time inte...
Conference Paper
Full-text available
During the Eocene-Oligocene transition (EOT), the world changed from a high-pCO 2 warm Eocene world to a cool, lower pCO 2 Oligocene world, oceanic phytoplankton was affected in various ways (Persico & Villa, 2004; Dunkley Jones et al., 2008; Henderiks & Pagani, 2008). To unravel the relations between changes in climatic and calcareous nannofossil...
Article
The environmental impact of the Paleocene-Eocene Thermal Maximum (PETM) has been intensively studied in the New Jersey Coastal Plain, but the benthic foraminiferal response, reflecting bottom water conditions, has not been documented at high resolution. We use benthic foraminiferal data across the Paleocene-Eocene boundary in cores from Wilson Lake...
Article
Full-text available
The onset of the Paleocene/Eocene thermal maximum (PETM) and associated carbon isotope excursion (CIE; about 56 million years ago) was geologically abrupt but it is debated whether it took thousands of years or was effectively instantaneous. A significant new record of the onset of the CIE was published by Wright and Schaller (2013) who claimed tha...