ORCID Profile
0000-0002-1710-4012
Current Organisation
Universiteit Utrecht
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Publisher: Copernicus GmbH
Date: 13-02-2018
Abstract: Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop s ling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.
Publisher: Copernicus GmbH
Date: 24-08-2021
Publisher: Copernicus GmbH
Date: 15-02-2022
Abstract: Abstract. Having descended through the water column, microplankton in ocean sediments is representative of the ocean surface environment, where it originated. Sedimentary microplankton is therefore used as an archive of past and present surface oceanographic conditions. However, these particles are advected by turbulent ocean currents during their sinking journey. So far, it is unknown to what extent this particle advection shapes the microplankton composition in sediments. Here we use global simulations of sinking particles in a strongly eddying global ocean model, and define ocean bottom provinces based on the particle surface origin locations. We find that these provinces can be detected in global datasets of sedimentary microplankton assemblages, demonstrating the effect provincialism has on the composition of sedimentary remains of surface plankton. These provinces explain the microplankton composition, in addition to, e.g., the ocean surface environment. Connected provinces have implications for the optimal spatial extent of microplankton sediment s le datasets that are used for palaeoceanographic reconstruction, and for the optimal spatial averaging of sediment s les over global datasets.
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-5705
Abstract: & & & & & span& When faced with a question, scientists and scholars are trained to& search& academic and informal& literature to find& the answer.& But where& can& the public& find reliable& answers to& questions about the climate crisis?& After all,& the climate crisis& is a topic about which our understanding& rapidly& evolves& across a wide array of disciplines.& The validity& and reliability& of& offered& information is difficult to& assess& for non-specialists, while scientific consensus is& sometimes deliberately undermined& in popular articles. Moreover,& civil& questions about& the& climate& crisis& can be very specific, pragmatic or locally applicable, so not all answers can be found on popular sources& that& commonly& rovide only the theoretical principles or general background.& This raises the question how we can connect citizens with climate-related questions to understandable scientific expert& & /span& & span& knowledge& /span& & span& .& /span& & & & / & & & & & & span& KlimaatHelpdesk.org& is meant to become the go-to place in the Netherlands for& citizens& with climate-related questions. It is a unique,& independent,& and accessible c& /span& & span& ommunications& /span& & span& & latform that connects the& ublic& with scientists and experts, run by a volunteer group& of students and academics. People who ask& a& question on this platform will receive& a& eer-reviewed answer to their question from a network of affiliated scholars and experts. KlimaatHelpdesk& archives& the& & /span& & span& question and& & /span& & span& corresponding& & /span& & span& answer& /span& & span& & on the website and thereby& rovides an& expanding,& easily accessible source of reliable and evidence-based information. Since the official launch in November 2020, more than& & enthusiastic experts& have& answered and/or reviewed& over& & questions& in a variety of disciplines:& from& meteorology, oceanography and biology to psychology,& law,& and philosophy.& /span& & & & / & & & & & & span& KlimaatHelpdesk& also serves as& a platform for students and young academics to get involved in science outreach and public engagement, and for scientists to explain their& research& to a targeted audience.& While& KlimaatHelpdesk& is further& expanding its& reach in& the Netherlands,& & /span& & span& we also work to make& the& latform portable to other& countries and disciplines. We are& eager and& ready to share our gained experience& with the wider& Science Communication, Engagement & Outreach& community.& /span& & & & / &
Publisher: Springer Science and Business Media LLC
Date: 08-2012
DOI: 10.1038/NATURE11300
Abstract: The warmest global climates of the past 65 million years occurred during the early Eocene epoch (about 55 to 48 million years ago), when the Equator-to-pole temperature gradients were much smaller than today and atmospheric carbon dioxide levels were in excess of one thousand parts per million by volume. Recently the early Eocene has received considerable interest because it may provide insight into the response of Earth's climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions. Climatic conditions of the early Eocene 'greenhouse world', however, are poorly constrained in critical regions, particularly Antarctica. Here we present a well-dated record of early Eocene climate on Antarctica from an ocean sediment core recovered off the Wilkes Land coast of East Antarctica. The information from biotic climate proxies (pollen and spores) and independent organic geochemical climate proxies (indices based on branched tetraether lipids) yields quantitative, seasonal temperature reconstructions for the early Eocene greenhouse world on Antarctica. We show that the climate in lowland settings along the Wilkes Land coast (at a palaeolatitude of about 70° south) supported the growth of highly erse, near-tropical forests characterized by mesothermal to megathermal floral elements including palms and Bombacoideae. Notably, winters were extremely mild (warmer than 10 °C) and essentially frost-free despite polar darkness, which provides a critical new constraint for the validation of climate models and for understanding the response of high-latitude terrestrial ecosystems to increased carbon dioxide forcing.
Publisher: Copernicus GmbH
Date: 05-04-2016
Abstract: Abstract. The timing and role in ocean circulation and climate of the opening of Southern Ocean gateways is as yet elusive. Recent micropalaeontological studies suggest the onset of westward throughflow of surface waters from the SW Pacific into the Australo-Antarctic Gulf through a southern shallow opening of the Tasman Gateway from 49–50 Ma onwards, a direction that is counter to the present-day eastward-flowing Antarctic Circumpolar Current. Here, we present the first model results specific to the early-to-middle Eocene where, in agreement with the field evidence, southerly shallow opening of the Tasman Gateway indeed causes a westward flow across the Tasman Gateway. As a result, modelled estimates of dinoflagellate biogeography are in agreement with the recent findings. Crucially, in this situation where Australia is still situated far south and almost attached to Antarctica, the Drake Passage must be sufficiently restricted to allow the prevailing easterly wind pattern to set up this southerly restricted westward flow. In contrast, an open Drake Passage, up to 517 m deep, leads to an eastward flow, even when the Tasman Gateway and the Australo-Antarctic gulf are entirely contained within the latitudes of easterly wind.
Publisher: Copernicus GmbH
Date: 22-10-2018
Abstract: Abstract. An International Ocean Discovery Program (IODP) workshop was held at Sydney University, Australia, from 13 to 16 June 2017 and was attended by 97 scientists from 12 countries. The aim of the workshop was to investigate future drilling opportunities in the eastern Indian Ocean, southwestern Pacific Ocean, and the Indian and Pacific sectors of the Southern Ocean. The overlying regional sedimentary strata are underexplored relative to their Northern Hemisphere counterparts, and thus the role of the Southern Hemisphere in past global environmental change is poorly constrained. A total of 23 proposal ideas were discussed, with ∼ 12 of these deemed mature enough for active proposal development or awaiting scheduled site survey cruises. Of the remaining 11 proposals, key regions were identified where fundamental hypotheses are testable by drilling, but either site surveys are required or hypotheses need further development. Refinements are anticipated based upon regional IODP drilling in 2017/2018, analysis of recently collected site survey data, and the development of site survey proposals. We hope and expect that this workshop will lead to a new phase of scientific ocean drilling in the Australasian region in the early 2020s.
Publisher: American Geophysical Union (AGU)
Date: 03-2023
DOI: 10.1029/2022PA004529
Abstract: To assess zonal temperature and biogeographical patterns in the Southern Ocean during the Paleogene, we present new multi‐proxy air‐ and sea‐surface temperature data for the latest Paleocene (∼57–56 Ma) and the Paleocene‐Eocene Thermal Maximum (PETM ∼56 Ma) from the northern margin of the Australo‐Antarctic Gulf (AAG). The various proxy data sets document the well‐known late Paleocene warming and, superimposed, two transient late Paleocene pre‐cursor warming events, hundreds of kyr prior to the PETM. Remarkably, temperature reconstructions for the AAG and southwest Pacific during the latest Paleocene, PETM and Early Eocene Climatic Optimum (∼53–49 Ma) show similar trends as well as similar absolute temperatures east and west of the closed Tasmanian Gateway. Our data imply that the exceptional warmth as recorded by previous studies for the southwest Pacific extended westward into the AAG. This contrasts with modeling‐derived circulation and temperature patterns. We suggest that simulations of ocean circulation underestimate heat transport in the southwest Pacific due to insufficient resolution, not allowing for mesoscale eddy‐related heat transport. We argue for a systematic approach to tackle model and proxy biases that may occur in marginal marine settings and non‐analog high‐latitude climates to assess the temperature reconstructions.
Publisher: Copernicus GmbH
Date: 24-08-2021
DOI: 10.5194/ESD-2021-48
Abstract: Abstract. Having descended through the water column, microplankton in ocean sediments are representative for the ocean surface environment, where they originated from. Sedimentary microplankton is therefore used as an archive of past and present surface oceanographic conditions. However, these particles are advected by turbulent ocean currents during their sinking journey. So far, it is unknown to what extent this particle advection shapes the microplankton composition in sediments. Here we use global simulations of sinking particles in a strongly eddying global ocean model, and define ocean bottom provinces based on the particle surface origin locations. We find that these provinces can be detected in global datasets of sedimentary microplankton assemblages, demonstrating the effect provincialism has on the composition of sedimentary remains of surface plankton. These provinces explain the microplankton composition, together with e.g. ocean surface environment. Connected provinces have implications on the optimal spatial extent of microplankton sediment s le datasets that are used for palaeoceanographic reconstructions, and on the optimal spatial averaging of sediment s les over global datasets.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Springer Science and Business Media LLC
Date: 09-11-2021
DOI: 10.1038/S41467-021-26658-1
Abstract: Declining atmospheric CO 2 concentrations are considered the primary driver for the Cenozoic Greenhouse-Icehouse transition, ~34 million years ago. A role for tectonically opening Southern Ocean gateways, initiating the onset of a thermally isolating Antarctic Circumpolar Current, has been disputed as ocean models have not reproduced expected heat transport to the Antarctic coast. Here we use high-resolution ocean simulations with detailed paleobathymetry to demonstrate that tectonics did play a fundamental role in reorganising Southern Ocean circulation patterns and heat transport, consistent with available proxy data. When at least one gateway (Tasmanian or Drake) is shallow (300 m), gyres transport warm waters towards Antarctica. When the second gateway subsides below 300 m, these gyres weaken and cause a dramatic cooling (average of 2–4 °C, up to 5 °C) of Antarctic surface waters whilst the ACC remains weak. Our results demonstrate that tectonic changes are crucial for Southern Ocean climate change and should be carefully considered in constraining long-term climate sensitivity to CO 2 .
Publisher: Pensoft Publishers
Date: 08-03-2013
No related grants have been discovered for Peter Bijl.