Antje Helga Luise Voelker

Instituto Português do Mar e da Atmosfera | IPMA · Divisão de Geologia e Georecursos Marinhos

The Late Pliocene marks the intensification of Northern Hemisphere glaciation (iNHG), offering a unique opportunity to study climate evolution and ice-sheet-related feedback mechanisms. In this study, we present high-resolution Mg / Ca-based sea surface temperatures (SSTs) and subsurface temperatures (SubTs) derived from the foraminiferal species G...

Climate variability and glacial cycles during the Pleistocene era are well-studied phenomena, although less is known about the climate dynamics and their impact on benthic foraminiferal assemblages prior to the Mid Pleistocene Transition known as the ‘41 kyr world’. Benthic foraminiferal assemblages are sensitive to variations in factors such as fo...

The Early-Middle Pleistocene Transition (EMPT), a global climate event that occurred between 700-1250 thousand years (kyr) ago, was characterized by a drastic change in the deep thermohaline circulation, resulting in more intense and longer-lasting interglacial periods. High-resolution records documenting environmental changes on the ocean seafloor...

Species assemblage composition of marine microfossils offers the possibility to investigate ecological and climatological change on time scales inaccessible using conventional observations. Planktonic foraminifera - calcareous zooplankton - have an excellent fossil record and are used extensively in palaeoecology and palaeoceanography. During the L...

The intricate interplay among atmospheric CO 2 concentrations, surface ocean pH dynamics, and their profound impact on marine ecosystems is of paramount importance in the context of contemporary climate change. Pre-industrial atmospheric CO 2 concentrations oscillated in phase with glacial-interglacial cycles, showcasing low levels during glacial p...

The Late Pliocene marks the intensification of Northern Hemisphere Glaciation, offering a unique opportunity to study climate evolution and ice-sheet related feedback mechanisms. In this study, we present high-resolution Mg/Ca-based sea surface (SST) and subsurface temperatures (SubT) derived from foraminiferal species Globigerinoides ruber and Glo...

In order to understand the complex evolutionary processes and patterns that explain current island biodiversity, large datasets and long-term analysis are required. The Last Interglacial (LIG) was one of the warmest interglacials during the last million years. How species mobility changed during this period in the Macaronesia geographical region ha...

Planktonic foraminifera are commonly used as paleoclimatic tracers and have enabled millennial-scale reconstructions of climate variability, particularly in the Quaternary. So far little is known how climatic variations in the 41 kyr world, especially prior to the Mid-Pleistocene Transition, affected the planktonic foraminifera fauna. We are, there...

Benthic foraminifera assemblages can be used to trace trophic conditions and oxygen levels at the seafloor during the Early-Middle Pleistocene Transition (EMPT, 700-1250 kyr). The EMPT was an event that marked a change in how Earth's climate system responded to orbital forcing. Throughout the EMPT, the frequency of glacial-interglacial cycles shift...

We present the first version of the Ocean Circulation and Carbon Cycling (OC3) working group database, of oxygen and carbon stable isotope ratios from benthic foraminifera in deep ocean sediment cores from the Last Glacial Maximum (LGM, 23-19 ky) to the Holocene (<10 ky) with a particular focus on the early last deglaciation (19-15 ky BP). It inclu...

Changes in Earth’s orbital parameters pace the Pleistocene glacial-interglacial cycles, although considerable ambiguity still remains over the interaction of the internal climatic variables, such as ice-sheet instability and ocean circulation that allow transitions into and out of an interglacial. Here, we analyse high-resolution planktic foraminif...

Content Paleodata of environmental responses to climate change from the Last Glacial Maximum (LGM) and the Holocene provide a useful performance test for climate models' sensitivity, contributing to better forecasts. Temporal high resolution data for both periods is important to reduce the uncertainties of models regionally. The Portuguese margin,...

To assess the anthropogenic effect on biodiversity, it is essential to understand the global diversity distribution of the major groups at the base of the food chain, ideally before global warming initiation (1850 Common Era CE). Since organisms in the plankton are highly interconnected and carbonate synthesizing species have a good preservation st...

Analysis of benthic foraminifera assemblages from the Gulf of Cadiz reveal a considerable change in the abiotic factors such as oxygen levels and trophic conditions during the Early-Middle Pleistocene Transition (EMPT, 700-1250 kyr). The EMPT was a global climate event and characterized by a drastic change in the deep thermohaline circulation that...

Coccolithophore high resolution (300 years) quantitative analyses have been carried out on Early Pleistocene sediment samples from Integrated Ocean Drilling Program Site U1387 retrieved in the Gulf of Cadiz. The studied interval is well constrained by the δ¹⁸O chronological frame and covers marine isotope stage (MIS) 48 to MIS 45, from 1465.9 ka to...

In order to better understand interglacial climate variability within the 41 kyr world, we produced high-resolution climate records for interglacial Marine Isotope Stage (MIS) 47 (1424–1452 ka) at IODP Site U1387 (36°48′ N, 7°43′ W) on the southern Portuguese margin. Using benthic and planktonic foraminifera stable isotope records, Uk’37 sea-surfac...

We use eighteen timescale-synchronised near-surface temperature reconstructions spanning 10–50 thousand years before present to clarify the regional expression of Dansgaard-Oeschger (D-O) and Heinrich (H) events in the North Atlantic. The North Atlantic Drift region shows D-O temperature variations of ca. 2–5° with Greenland-like structure. The Wes...

It was with much interest that we read the comment made by Meco et al. (2022), regarding our work on "Range expansion of tropical shallow-water marine molluscs in the NE Atlantic during the last interglacial (MIS 5e): Causes, consequences and utility of ecostratigraphic indicators for the Macaronesian archipelagos". We welcome the discussion genera...

The characteristics of the CISE-LOCEAN seawater isotope dataset (δ18O, δ2H, referred to as δD) are presented (10.17882/71186; Waterisotopes-CISE-LOCEAN, 2021). This dataset covers the time period from 1998 to 2021 and currently includes close to 8000 data entries, all with δ18O, three-quarters of them also with δD, associated with a date stamp, spa...

The characteristics of the CISE-LOCEAN sea water isotope data set (δ18O, δ2H, later designed as δD) are presented. This data set covers the time period from 1998 to 2021 and currently includes close to 8000 data entries, all with δ18O, three quarters of them also with δD, associated with a time and space stamp and usually a salinity measurement. Un...

Controlled by ecological and physical factors, marine species distribution may vary due to global climatic changes that result from range expansion or contraction (the latter caused by local disappearances, i.e., extirpations). Spanning from 13° to 39°N, the Macaronesian region encompasses five archipelagos located within warm-temperate to tropical...

The marine topshell Phorcus sauciatus is currently found along the temperatesubtropical shores of the Northeast Atlantic Ocean. Although present in the Iberian Peninsula, Madeira and Canaries for centuries, P. sauciatus has only recently reached another oceanic volcanic archipelago in the region. In 2013, a small population was recorded for the fir...

Coccolithophores contribute significantly to marine primary productivity and play a unique role in ocean biogeochemistry by using carbon for photosynthesis (soft-tissue pump) and for calcification (carbonate counter pump). Despite the importance of including coccolithophores in Earth system models to allow better predictions of the climate system's...

Reconstruction of the Mediterranean Outflow Water (MOW) dynamics in the geologic past contributes to exploring its influence on the North Atlantic Ocean circulation and global climate. The middle Pleistocene transition (MPT) is one of the most important characteristics of Quaternary climate change, but until now, research on the MOW variability dur...

Marine Isotope Stage (MIS) 13,~533e478 ka, has received particular attention due to the unexpected enhancement of monsoon systems under a cool climate characterized by lower atmospheric CO 2 and larger ice volume than many other interglacials. Key questions remain about its regional expression (intensity, climate variability, length), and underlyin...

The Sines Contourite Drift (SCD), located in the Alentejo margin, southwest Iberian continental margin, has been through many depositional phases in result of climatic variations and bottom current oscillations, which determined a variable depositional pattern and an irregular sedimentary evolution since the Late Pleistocene. The SCD, being in the...

Sea surface temperature (SST) is used to infer past changes in the state of the climate system. Here we use a combination of newly generated and published organic paleothermometer records, together with novel high‐resolution benthic foraminiferal δ¹⁸O stratigraphy, from four sites in the midlatitude North Atlantic (41–58°N) to reconstruct the long‐...

The Mid Pleistocene Transition (MPT) was a global climatic event characterized by a drastic change in the deep thermohaline circulation during the glacial periods that resulted in more intense and longer lasting cold periods and cooler sea-surface temperature (SST). These changes might be linked to the atmospheric pCO 2 reduction which in turn led...

An underground record of past deglaciations Understanding more exactly how the timing of deglaciations depends on changes in insolation, or the energy received by Earth from the Sun, requires precise and independent records of both environmental change and solar energy input. Bajo et al . strengthened the weak link of that two-member chain, the env...

Planktonic foraminifera δ¹⁸O and Mg/Ca ratios are widely considered as a powerful proxy to reconstruct past seawater‐column temperature. Due to the complex interpretation of planktonic foraminifera δ¹⁸O data in regard to past seawater temperatures, temperature determination based on the foraminifera shell Mg/Ca ratio is believed to be more accurate...

The variable amounts of ice rafted debris (IRD) and foraminifers in North Atlantic sediments are related to the abrupt, millennial‐scale alteration from Greenland stadials to interstadials during the last glacial period and indicate past ice sheet instabilities, changes in sea‐ice cover and productivity. In the Norwegian Sea, Greenland stadials wer...

Abstract. Coccolithophores contribute significantly to the marine primary productivity and play a unique role in ocean biogeochemistry by using carbon for photosynthesis (biological pump) and also for calcification (carbonate pump). Despite the importance of including coccolithophores in global climate models to allow better predictions of the clim...

Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in cli...

Varied approaches (palaeobiodiversity, palaeobiogeography, bioerosion, geochemistry) to unique Patagonian late Quaternary molluscan assemblages in the southwestern Atlantic, with ages especially from interglacial Marine Isotope Stage (MIS) 5e and MIS 1, provide large-scale and long-temporal palaeoenvironmental data for the southern SWA. Together wi...

Stable oxygen isotopes (δ18O) of planktonic foraminifera are one of the most used tools to reconstruct environmental conditions of the water column. Since different species live and calcify at different depths in the water column, the δ18O of sedimentary foraminifera reflects to a large degree the vertical habitat and interspecies δ18O differences...

Paleoclimate reconstructions suggest that the complex variability within the Greenland stadial 1 (GS-1) over western Europe was governed by coupled ocean and atmospheric changes. However, few works from the North Atlantic mid-latitudes document both the GS-1 onset and its termination, which are often considered as single abrupt transition events. H...

This study identifies temporal biases in the radiocarbon ages of the planktonic foraminifera species Globigerina bulloides and Globigerinoides ruber (white) in a sediment core from the SW Iberian margin (so‐called Shackleton site). Leaching of the outer shell and measurement of the radiocarbon content of both the leachate and leached sample enabled...

Supporting Information S1

Understanding interglacial climate variability is a key issue in the scientific community. Here we compared records from Marine Isotope Stage (MIS) 11 to those from MIS 1 (Holocene) as they are perceived to be possible analogs. Our study on the Iberian Margin, a key area to investigate surface dynamics in the Atlantic Ocean, incorporates coccolitho...

Here, we establish a spatiotemporal evolution of the sea-surface temperatures in the North Atlantic over Dansgaard–Oeschger (DO) events 5–8 (approximately 30–40 kyr) using the proxy surrogate reconstruction method. Proxy data suggest a large variability in North Atlantic sea-surface temperatures during the DO events of the last glacial period. Howe...

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the pre...

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the pre...

Coccolithophores play a key role in the oceanic carbon cycle through the biological and carbonate pumps. Understanding controls on coccolithophore productivity is thus fundamental to quantify oceanic carbon cycling. We investigate changes in coccolithophore productivity over several Pleistocene glacial-interglacial cycles using a high-resolution co...

We document the history of terms used to describe Heinrich (H-) layers and events and which mark major glaciological iceberg discharge events in the North Atlantic. We argue that the usage “Heinrich layer,” “Heinrich zone”, or “Heinrich event” should be restricted to only those sediments that can be ascribed to an origin from the Hudson Strait Ice...

Significance Here, we present a precisely dated speleothem record of South American monsoon precipitation covering the period encompassed by the last six Heinrich Stadials. Our monsoon record allows us to determine the timing of regional hydroclimatic expression of Heinrich Stadials over tropical lowland South America. By comparing our record with...

The Iberian Margin is a sensitive area to track high and low latitude processes, and is a key location to understand major past climatic and oceanographic changes. Here we present new biomarker data from IODP Site U1385 (“Shackleton site”) (1017–336 ka) that, when combined with existing data from Cores MD01-2443/4 (last 335 ka), allows us to assess...

Here we establish a spatio-temporal evolution of the sea-surface temperatures in the North Atlantic over Dansgaard Oeschger (DO) events 5–8 (c. 30–40 ka) using the proxy surrogate reconstruction method. Proxy data suggest a large variability in North Atlantic sea-surface temperatures during the DO-events of the last glacial period. However, proxy d...

The sediment records from north and south of Denmark Strait (cores PS2644 and MD99-2323) and on the Kangerlussuaq Trough Mouth Fan (KTMF) (MD99-2260) are evaluated for the period 12 to 60 cal ka BP with the goal of evaluating: 1) the relative roles of the Greenland and Iceland Ice Sheets in sediment composition, 2) the processes of sediment supply,...

The presence and high abundances of the benthic foraminiferal group “elevated epifauna” has been proposed as indicator of the existence of Mediterranean Outflow Water (MOW) in the Gulf of Cadiz. Here we intend to use this potential proxy to reconstruct MOW in the early Pliocene at the Integrated Ocean Drilling Program (IODP) Hole U1387C. Cibicides...

Planktonic foraminifera preserved in marine sediments archive the physical and chemical conditions under which they built their shells. To interpret the paleoceanographic information contained in fossil foraminifera, the recorded proxy signals have to be attributed to the habitat and life cycle characteristics of individual species. Much of our kno...

Marine Isotope Stage 31 (MIS 31) is an important analogue for ongoing and projected global warming, yet key questions remain about the regional signature of its extreme orbital forcing and intra-interglacial variability. Based on a new direct land-sea comparison in SW Iberian margin IODP Site U1385 we examine the climatic variability between 1100 a...

American Geophysical Union (AGU) Fall Meeting 2016

New dinoflagellate cyst (dinocyst) analyses were carried out at high resolution in core MD99-2339, retrieved from a contouritic field in the central part of the Gulf of Cadiz, for the Marine Isotope Stage (MIS) 3 interval, allowing for discussion of palaeohydrological changes over the last 50 ky in the subtropical NE Atlantic Ocean. Some index dino...

Planktonic foraminifera preserved in marine sediments archive the physical and chemical conditions under which they built their shells. To interpret the paleoceanographic information contained in fossil foraminifera, the proxy signals have to be attributed to the habitat of individual species. Much of our knowledge on habitat depth is based on indi...

New dinoflagellate cyst (dinocyst) analyses were carried out at high-resolution in core MD99-2339, retrieved from a contouritic field in the central part of the Gulf of Cadiz, for the Marine Isotope Stage (MIS) 3 interval, allowing to discuss paleohydrological changes over the last 50 ky in the subtropical NE Atlantic Ocean. Some index dinocyst tax...

The Contourite Depositional Systems (CDS) in the Gulf of Cádiz and on the West Iberian margin preserve a unique archive of Mediterranean Outflow Water (MOW) variability over the past 5.3 Ma. These CDS have been recently drilled in several places during the IODP Expedition 339. These drill sites now offer a new window to the internal Pliocene and Qu...

The mode and vigor of the global oceanic circulation critically depend on the salinity of (sub)surface water masses advected to the lociof deep-water formation. Within the Atlantic meridional overturning circulation (AMOC), an important supplier of high-salinity waters is the Mediterranean Outflow Water (MOW), discharging into the North Atlantic vi...

Centennial-to-millennial scale records from IODP Site U1387, drilled during IODP Expedition 339 into the Faro Drift at 558 m water depth, now allow evaluating the climatic history of the upper core of the Mediterranean Outflow (MOW) and of the surface waters in the northern Gulf of Cadiz during the early Pleistocene. This study focuses on the perio...