Thomas Westerhold

Thomas Westerhold
Universität Bremen | Uni Bremen · MARUM - Center for Marine Environmental Sciences

Dr. rer. nat.

About

197
Publications
56,384
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6,232
Citations
Citations since 2016
92 Research Items
4373 Citations
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20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
Introduction
Thomas Westerhold currently works at the MARUM - Center for Marine Environmental Sciences, Universität Bremen. Thomas does research in Geology, Geochemistry and Paleoclimatology.
Additional affiliations
January 2004 - present
Universität Bremen

Publications

Publications (197)
Article
Full-text available
Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ¹⁸O records versus age (LR04 stack). In this study LR04 is compared to high-resolution records collected at all of the sites drilled durin...
Article
Full-text available
To fully understand the global climate dynamics of the warm early Eocene with its reoccurring hyperthermal events, an accurate high-fidelity age model is required. The Ypresian stage (56–47.8 Ma) covers a key interval within the Eocene as it ranges from the warmest marine temperatures in the early Eocene to the long-term cooling trends in the middl...
Article
Full-text available
A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, at 56–54 Ma, show the impact of large-scale carbon input into the ocean–atmosphere system. Here we provide the first timescale synchroniza...
Article
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Studying the dynamics of past global warming events during the late Paleocene to middle Eocene informs our understanding of Earth's carbon cycle behavior under elevated atmospheric pCO2 conditions. Due to sparse data coverage, the spatial character of numerous hyperthermal events during this period is still poorly constrained. Here we present a hig...
Article
Full-text available
Much of our understanding of Earth's past climate comes from the measurement of oxygen and carbon isotope variations in deep-sea benthic foraminifera. Yet, long intervals in existing records lack the temporal resolution and age control needed to thoroughly categorize climate states of the Cenozoic era and to study their dynamics. Here, we present a...
Article
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The absolute position during the Cenozoic of northern Zealandia, a continent that lies more than 90% submerged in the southwest Pacific Ocean, is inferred from global plate motion models, because local paleomagnetic constraints are virtually absent. We present new paleolatitude constraints using paleomagnetic data from International Ocean Discovery...
Preprint
Cyclostratigraphy and astrochronology are now at the forefront of geologic timekeeping. While this technique heavily relies on the accuracy of astronomical calculations, solar system chaos limits how far back astronomical calculations can be performed with confidence. High-resolution paleoclimate records with Milankovitch imprints now allow reversi...
Article
The western equatorial Pacific is pivotal to precisely understand the global climate change and its evolution over geological time. However, continuous paleoceanographic records with high time resolution and accurate age model over the last 5 Myr are few in this important ocean region. Here, we present a high time resolution (2–3 kyr) benthic foram...
Article
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A mile-high marine cascade terminated the Messinian salinity crisis 5.33 Myr ago, due to partial collapse of the Gibraltar sill that had isolated a largely desiccated Mediterranean from the Atlantic Ocean. Atlantic waters may have refilled the basin within 2 years. Prevailing hypotheses suggest that normal marine conditions were established across...
Article
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The Sahara is the largest hot desert on Earth. Yet the timing of its inception and its response to climatic forcing is debated, leading to uncertainty over the causes and consequences of regional aridity. Here we present detailed records of terrestrial inputs from Africa to North Atlantic deep-sea sediments, documenting a long and sustained history...
Preprint
Full-text available
The marine biological carbon pump, which exports organic carbon out of the surface ocean, plays an essential role in sequestering carbon from the atmosphere, thus impacting climate and affecting marine ecosystems. Orbital variations in solar insolation modulate these processes, but their influence on the tropical Pacific during the Late Cretaceous...
Preprint
Full-text available
Marine plankton is an important component of the global carbon cycle. Whereas the production and seafloor export of organic carbon produced by the plankton, the biological pump, has received much attention, the long-term variability in plankton calcification, controlling the carbonate counter pump, remains less well understood. Yet, it has been sho...
Article
Postcruise examination of the data splice for International Ocean Discovery Program Expedition 378 Site U1553, in light of new X-ray fluorescence data, revealed three cores from Hole U1553E that were misaligned. These cores have been shifted to fill in some gaps in the original splice.
Article
A near-complete sedimentary sequence was spliced together for the upper part of International Ocean Discovery Program (IODP) Holes U1553A, U1553B, and U1553E. Poor core recovery precluded a complete splice for the deeper section cored in Holes U1553C and U1553D. The history of Deep Sea Drilling Project Site 277, which was cored nearby, suggests tha...
Article
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Sediment mass accumulation rate (MAR) is a proxy for paleoceanographic conditions, especially if biological productivity generated most of the sediment. We determine MAR records from pelagic calcareous sediments in Tasman Sea based on analysis of 11 boreholes and >3 million seismic reflection horizon picks. Seismic data from regions of 10,000–30,00...
Article
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Rapid onset of subduction tectonics across the western Pacific convergent margins in the early Eocene was followed by a slower phase of margin growth of the proto Tonga-Kermadec subduction system north of Zealandia during a middle Eocene phase to tectonic adjustment. We present new age constraints from International Ocean Discovery Program Expediti...
Article
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Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during Green Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, hi...
Article
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The Western Pacific Warm Pool (WPWP) is a major source of heat and moisture to the atmosphere. Small perturbations in WPWP sea-surface temperatures greatly influence local Hadley and Walker cells, thereby affecting global atmospheric circulation patterns. International Ocean Discovery Program (IODP) Expedition 363 sought to document the regional ex...
Article
Deep-time paleoclimatic records document large-scale shifts and perturbations in Earth's climate; during the Cenozoic in particular transitions have been recorded on time scales of 10 thousand to 1 million years. Bifurcations in the leading dynamical modes could be a key element driving these events. Such bifurcation-induced critical transitions ar...
Article
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Environmental and biotic responses to early Eocene hyperthermal events in the southwest Pacific are critical for global paleoclimate reconstructions during Cenozoic greenhouse intervals, but detailed multidisciplinary studies are generally missing from this time and location. Eocene carbonate sediments were recovered during International Ocean Disc...
Preprint
Full-text available
Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during ‘Green’ Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term,...
Article
Full-text available
Future environmental change may profoundly affect oceanic ecosystems in a complex way, due to the synergy between rising temperatures, reduction in mixing and upwelling due to enhanced stratification, ocean acidification, and associated biogeochemical dynamics. Changes in primary productivity, in export of organic carbon from the surface ocean, and...
Article
The Mid-Pleistocene transition (MPT; 1200 to 800 thousand years, kyr) is marked by the shift from 41-kyr to 100-kyr interglacial-glacial cyclicity without substantial change in the astronomical forcing. This change in climate response relied on internal feedback processes including interaction between ice sheet/sea ice, ocean circulation and the ca...
Preprint
Full-text available
The evolution of the Cenozoic Icehouse over the past 30 million years (Myr) from a unipolar to a bipolar world is broadly known; however, the exact development of orbital-scale climate variability is less well understood. Highly resolved records of carbonate (CaCO3) content provide insight into the evolution of regional and global climate, cryosphe...
Article
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Data from International Ocean Discovery Program (IODP) Expedition 371 reveal vertical movements of 1–3 km in northern Zealandia during early Cenozoic subduction initiation in the western Pacific Ocean. Lord Howe Rise rose from deep (~1 km) water to sea level and subsided back, with peak uplift at 50 Ma in the north and between 41 and 32 Ma in the s...
Article
Understanding the role of deep-sea biota across global warming events in the past is key to unravel climate system dynamics during periods of increased pCO2 levels. Here we present the first record of the benthic foraminiferal response to a middle Eocene transient warming event named Late Lutetian Thermal Maximum (LLTM; 41.52 Ma) at ODP Site 702 in...
Article
An impact with a dash of volcanism Around the time of the end-Cretaceous mass extinction that wiped out dinosaurs, there was both a bolide impact and a large amount of volcanism. Hull et al. ran several temperature simulations based on different volcanic outgassing scenarios and compared them with temperature records across the extinction event. Th...
Article
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The early to middle Eocene is marked by prominent changes in calcareous nannofossil assemblages coinciding both with long‐term climate changes and modification of the North Atlantic deep ocean circulation. In order to assess the impact of Eocene climate change on surface water environmental conditions of the Northwest Atlantic, we developed calcare...
Article
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The Middle Eocene Climatic Optimum (MECO) was an unusual global warming event that interrupted the long‐term Eocene cooling trend ca. 40 Ma. Here we present new high‐resolution bulk and benthic isotope records from South Atlantic ODP Site 702 to characterize the MECO at a high latitude setting. The MECO event, including early and peak warming as we...
Article
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Coherent variation in CaCO3 burial is a feature of the Cenozoic eastern equatorial Pacific. Nevertheless, there has been a long-standing ambiguity in whether changes in CaCO3 dissolution or changes in equatorial primary production might cause the variability. Since productivity and dissolution leave distinctive regional signals, a regional synthesi...
Article
Full-text available
The evolution of the Cenozoic cryosphere from unipolar to bipolar over the past 30 million years (Myr) is broadly known. Highly resolved records of carbonate (CaCO3) content provide insight into the evolution of regional and global climate, cryosphere, and carbon cycle dynamics. Here, we generate the first Southeast Atlantic CaCO3 content record sp...
Article
Full-text available
The early Eocene (56 to 48 million years ago) is inferred to have been the most recent time that Earth's atmospheric CO2 concentrations exceeded 1000 ppm. Global mean temperatures were also substantially warmer than those of the present day. As such, the study of early Eocene climate provides insight into how a super-warm Earth system behaves and o...
Conference Paper
Recognizing past events of transient global warming triggered by release of carbon into the ocean-atmosphere system is important for understanding Earth´s climate under elevated pCO2 conditions. These events, called hyperthermals, are recognized in the marine geological record by shifts in the δ13C and δ18O in carbonate and shells. Several hyperthe...
Article
Full-text available
The Late Cretaceous–Early Paleogene is the most recent period in Earth history that experienced sustained global greenhouse warmth on multimillion year timescales. Yet, knowledge of ambient climate conditions and the complex interplay between various forcing mechanisms are still poorly constrained. Here we present a 14.75 million-year-long, high-re...
Article
The Global Stratotype Section and Point (GSSP) approach to define stage boundaries leaves the unit or body of the stage undefined. At the same time, previous arguments against the use of unit-stratotypes have been invalidated for the younger Cenozoic part of the geological record through the revolutionary advance in integrated high-resolution strat...
Article
Full-text available
The mathematically predictable cyclic movements of Earth with respect to the sun provides the basis for constructing highly accurate and precise age models for Earth’s past. Construction of these astronomically calibrated timescales is pivotal to placing major transitions and events in the geological record in their temporal context. Understanding...
Preprint
Full-text available
The early Eocene (56 to 48 million years ago) is inferred to have been the most recent time that Earth's atmospheric CO2 concentrations exceeded 1000 ppm. Global mean temperatures were also substantially warmer than present day. As such, study of early Eocene climate provides insight into how a super-warm Earth system behaves and offers an opportun...
Article
Full-text available
We report late Miocene-Recent time series of XRF-derived bulk sediment composition and mass accumulation rates (MAR) from IODP Sites U1335, U1337, U1338 and ODP Site 849, and also report bulk density-derived CaCO3 MAR at Sites 848, 850 and 851. We use physical properties and images to intercorrelate all records for the last 8Myr with resolutions of...
Article
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The response of the Earth system to greenhouse-gas-driven warming is of critical importance for the future trajectory of our planetary environment. Hyperthermal events – past climate transients with global-scale warming significantly above background climate variability – can provide insights into the nature and magnitude of these responses. The la...
Article
Full-text available
Ocean Drilling Program (ODP) Site 982 represents a key location for understanding the evolution of climate in the North Atlantic over the past 12 Ma. However, concerns exist about the validity and robustness of the underlying stratigraphy and astrochronology, which currently limits the adequacy of this site for high-resolution climate studies. To r...
Article
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The late Miocene-early Pliocene was a time of global cooling and the development of modern meridional thermal gradients. Equatorial Pacific sea surface conditions potentially played an important role in this global climate transition, but their evolution is poorly understood. Here, we present the first continuous late Miocene-early Pliocene (8.0-4....
Article
Full-text available
The Paleocene – Eocene Thermal Maximum (PETM; 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many mid- and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning and migr...