Appy Sluijs

• Dr.
• Professor at Utrecht University

Reactions between terrigenous sediments, marine-biogenic substances and seawater modulate multiple biogeochemical cycles, but the dynamics and factors governing these reactions are poorly constrained. Deltaic mobile muds are a major sedimentary facies along river-dominated ocean margins through which most terrigenous sediment transits and mixes wit...

Arctic PETM dinocysts of Sluijs and Brinkhuis 2024

The stable carbon isotope composition (δ13C) of plants and algae is influenced by environmental factors, such as pCO2, water availability, and altitude. To effectively use the δ13C of fossil material as proxies for these parameters, it is essential to understand the chemical and isotopic effects of diagenesis and conventional chemical treatments. I...

Marine glycerol dialkyl glycerol tetraethers (GDGTs) are used in various proxies (such as TEX86) to reconstruct past ocean temperatures. Over 20 years of improvements in GDGT sample processing, analytical techniques, data interpretation and our understanding of proxy functioning have led to the collective development of a set of best practices in a...

The Norwegian Sea is crucial for ocean circulation and global climate and has therefore long been a focus in paleoceanography. However, precise dating of sediments has often proved difficult, due to poor preservation and endemism among microfossils and the discontinuous nature of many records. One important Norwegian Sea Site, Ocean Drilling Progra...

The Paleocene‐Eocene Thermal Maximum (PETM, ∼56 Ma), was a transient episode of global warming, and caused profound changes in biology and climate. The evolution of the hydroclimate during the PETM in East Asia, which currently is influenced by the Asian Monsoon and hosts ∼20% of the world's population, is crucial to understand the future monsoon a...

Early Eocene (∼56–48 Ma) climates are useful to investigate polar climate dynamics in the absence of ice. We explore early Eocene orbital variability of Arctic climate using sediments recovered by the Arctic Coring Expedition (ACEX). High resolution records of lipid biomarkers (GDGTs; 2‐kyr) and palynological assemblages (5‐kyr) in the ∼4 m interva...

Based on a new cored succession at Winterswijk, evidence is uncovered of the end-Triassic mass-extinction (ETME) event in a subsurface sedimentary succession of the Netherlands. The ETME was one of the most devastating events for the biosphere during the Phanerozoic era. Massive volcanism from the Central Atlantic Magmatic Province initiated the br...

Plain Language Summary Modern tropical coral reefs are found approximately between 30° north and south of the equator, where waters are warmer than 16°C year‐round. It is therefore often assumed that water temperature has the most important control on how far poleward we find tropical coral reefs. In the geological past, the earth has seen periods...

Palynomorphs, notably sporomorphs and organic-walled dinoflagellate cysts, or “dinocysts”, are the only abundant microfossils consistently present in the sole available central Arctic upper Paleocene to lower Eocene sedimentary succession recovered at the central Lomonosov Ridge by the Integrated Ocean Drilling Program (IODP) Expedition 302 (or the...

Modern tropical coral reefs are found approximately between 30° north and south of the equator, where waters are warmer than 16°C year-round. It is therefore often assumed that water temperature has the most important control on how far poleward we find tropical coral reefs. In the geological past, the earth has seen periods when global temperature...

Ratios of glycerol dialkyl glycerol tetraethers (GDGT), which are membrane lipids of bacteria and archaea, are at the base of several paleoenvironmental proxies. They are frequently applied to soils as well as lake‐ and marine sediments to generate records of past temperature and soil pH. To derive meaningful environmental information from these re...

The functioning of the Pacific Ocean—the world's largest ocean—during a warmer‐than‐present paleoclimate state remains underexplored. We present planktonic and benthic foraminiferal stable oxygen (δ¹⁸O) and carbon (δ¹³C) isotope records from Integrated Ocean Drilling Program (IODP) Site U1334 that span the Oligocene‐Miocene Transition (OMT) interva...

Climate variability is typically amplified towards polar regions. The underlying causes, notably albedo and humidity changes, are challenging to accurately quantify with observations or models, thus hampering projections of future polar amplification. Polar amplification reconstructions from the ice-free early Eocene (∼56–48 Ma) can exclude ice alb...

Studying monsoon dynamics during past warm time periods such as the Miocene Climatic Optimum (MCO; ∼16.9–14.5 Ma) could greatly aid in better projecting monsoon intensity, in the context of future greenhouse warming. However, studies on regional MCO temperature change and its effect on the monsoons during this time period are lacking. Here, we pres...

Detailed analysis of tropical climate dynamics is lacking for the Early to Middle Miocene, even though this time interval bears important analogies for future climates. Based on high‐resolution proxy reconstructions of sea surface temperature, export productivity and dust supply at Ocean Drilling Program Site 959, we investigate astronomical forcin...

The long-term effects of the Central Atlantic Magmatic Province, a large igneous province connected to the end-Triassic mass-extinction (201.5 Ma), remain largely elusive. Here, we document the persistence of volcanic-induced mercury (Hg) pollution and its effects on the biosphere for ~1.3 million years after the extinction event. In sediments reco...

A series of transient global warming events (“hyperthermals”) in the early Eocene is marked by massive environmental and carbon cycle change. Among these events, the impacts of the Paleocene Eocene Thermal Maximum (~56 Ma), Eocene Thermal Maximum 2 (~54 Ma) and Eocene Thermal Maximum 3 (~53 Ma) are relatively well documented, but much less is known...

We explore the imprint of orbital variability on Arctic temperature and hydrology using sediments recovered during the Arctic Coring Expedition in 2004. High resolution records of lipid biomarkers (GDGTs; 2-kyr) and palynological assemblages (5-kyr) in the ~4 m interval below Eocene Thermal Maximum 2 (~54 Ma) show highly cyclic signals related to ~...

The release of over 4500 Gt (gigatonnes) of carbon at the Paleocene–Eocene boundary provides the closest geological analog to modern anthropogenic CO2 emissions. The cause(s) of and responses to the resulting Paleocene–Eocene Thermal Maximum (PETM) and attendant carbon isotopic excursion (CIE) remain enigmatic and intriguing despite over 30 years o...

The Paleocene‐Eocene Thermal Maximum (PETM) was a transient global warming event and is recognized in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was due to a rapid influx of ¹³C‐depleted carbon into the ocean‐atmosphere system. However, the mechanisms required to sustain the negative CIE remains...

Understanding the extreme greenhouse of the Eocene (56–34 Ma) is key to anticipating potential future conditions. While providing an end member towards a distant high-emission scenario, the Eocene climate also challenges the different tools at hand to reconstruct such conditions. Besides remaining uncertainty regarding the conditions under which th...

The Oligocene (33.9–23.03 Ma) was characterised by generally warm climates, with flattened meridional temperature gradients while Antarctica retained a significant cryosphere. This makes the Oligocene an imperfect analogue to long-term future climate states with unipolar icehouse conditions. Although local and regional climate and environmental rec...

Gradual climate cooling and CO2 decline in the Miocene were recently shown not to be associated with major ice volume expansion, challenging a fundamental paradigm in the functioning of the Antarctic cryosphere. Here, we explore Miocene ice-ocean-climate interactions by presenting a multi-proxy reconstruction of subtropical front migration, bottom...

The Paleocene-Eocene Thermal Maximum (PETM) was a transient global warming event recognised in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was the result of a rapid influx of 13C-depleted carbon into the ocean-atmosphere system. However, the mechanisms required to sustain the negative CIE remains...

The Paleocene-Eocene Thermal Maximum (PETM) was a transient global warming event recognised in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was the result of a rapid influx of 13C-depleted carbon into the ocean-atmosphere system. However, the mechanisms required to sustain the negative CIE remains...

The long-term effects of the Central Atlantic Magmatic Province (CAMP), a large igneous province connected to the end-Triassic mass-extinction (201.5 Ma), remain largely elusive. Here, we document the persistence of volcanic-induced mercury pollution and its effects on the biosphere for 2 million years after the extinction event. In sediments recov...

Studying West African Monsoon (WAM) dynamics during past warm time periods such as the Miocene Climatic Optimum (MCO; ~16.9 – 14.5 Ma) could greatly aid in better projecting monsoon intensity, in the context of future greenhouse warming. However, studies on regional MCO temperature change and its effect on the WAM system during this time period are...

Detailed analysis of tropical climate dynamics is lacking for the Early to Middle Miocene, even though this time interval bears important analogies for future climates. Based on high-resolution proxy reconstructions of sea (sub)surface temperature, export productivity and dust supply at Ocean Drilling Program Site 959, we investigate orbital forcin...

Climate variability is typically amplified towards polar regions. The underlying causes, notably albedo and humidity changes, are challenging to accurately quantify with observations or models, hampering projections of future polar amplification. Polar amplification reconstructions from the ice-free early Eocene (~56–48 million years ago) can exclu...

Eocene transient global warming events (hyperthermals) can provide insight into a future warmer world. While much research has focused on the Paleocene–Eocene Thermal Maximum (PETM), hyperthermals of a smaller magnitude can be used to characterize climatic responses over different magnitudes of forcing. This study identifies two events, namely the...

Disturbances in terrestrial vegetation across the end-Triassic mass-extinction (ETME) and earliest Jurassic (~201.5 - 201.3 Ma) have previously been linked to carbon cycle perturbations induced by the Central Atlantic Magmatic Province. Large-scale volcanic degassing has been proposed to have affected the terrestrial realm through various mechanism...

The Middle Eocene Climatic Optimum (around 40 million years ago) was a roughly 400,000-year-long global warming phase associated with an increase in atmospheric CO2 concentrations and deep-ocean acidification that interrupted the Eocene’s long-term cooling trend. The unusually long duration, compared with early Eocene global warming phases, is puzz...

Understanding the extreme greenhouse of the Eocene (56–34Ma ago) is key to anticipate potential future conditions. During the Eocene, the Antarctic continent remained mostly ice-free despite large temperature swings. Seemingly contradictory indications of ice and thriving vegetation complicate modelling efforts to explain the Antarctic Eocene clima...

Superimposed on long-term late Paleocene-early Eocene warming (~59 to 52 million years ago), Earth's climate experienced a series of abrupt perturbations, characterized by massive carbon input into the ocean-atmosphere system and global warming. Here, we examine the three most punctuated events of this period, the Paleocene-Eocene Thermal Maximum a...

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...

Rivers play a key role in the global carbon cycle by transporting terrestrial organic matter (TerrOM) from land to the ocean. Upon burial in marine sediments, this TerrOM may be a significant long-term carbon sink, depending on its composition and properties. However, much remains unknown about the dispersal of different types of TerrOM in the mari...

Eocene transient global warming events (hyperthermals) can provide insight into a future, warmer world. While much research has focused on the Paleocene-Eocene Thermal Maximum (PETM), hyperthermals of smaller magnitude can be used to characterize climatic responses over different magnitudes of forcing. This study identifies two events, Eocene Therm...

Quantitative reconstructions of hydrological change during ancient greenhouse warming events provide valuable insight into warmer-than-modern hydrological cycles but are limited by paleoclimate proxy uncertainties. We present sea surface temperature (SST) records and seawater oxygen isotope (δ18Osw) estimates for the Middle Eocene Climatic Optimum...

The middle Eocene climatic optimum (ca. 40 Ma) stands out as a transient global warming phase of ∼400 k.y. duration that interrupted long-term Eocene cooling; it has been associated with a rise in atmospheric CO2 concentrations that has been linked to a flare-up in Arabia-Eurasia continental arc volcanism. Increased organic carbon burial in the Tet...

TEX86 is a paleothermometer based on Thaumarcheotal glycerol dialkyl glycerol tetraether (GDGT) lipids and is one of the most frequently used proxies for sea-surface temperature (SST) in warmer-than-present climates. However, GDGTs are not exclusively produced in and exported from the mixed layer, so sedimentary GDGTs may contain a depth-integrated...

Model simulations of past climates are increasingly found to compare well with proxy data at a global scale, but regional discrepancies remain. A persistent issue in modeling past greenhouse climates has been the temperature difference between equatorial and (sub‐)polar regions, which is typically much larger in simulations than proxy data suggest....

Global mean sea level is a key component within the fields of climate and oceanographic modelling in the Anthropocene. Hence, an improved understanding of eustatic sea level in deep time aids in our understanding of Earth’s paleoclimate and may help predict future climatological and sea level changes. However, long-term eustatic sea level reconstru...

One of the great challenges in biogeochemical research over the past half a century has been to quantify and understand the mechanisms underlying stable carbon isotope fractionation (εp) in phytoplankton in response to changing CO2 concentrations. This interest is partly grounded in the use of fossil photosynthetic organism remains as a proxy for p...

Sedimentary bulk organic matter and various molecular organic components exhibit strong CO2-dependent carbon isotope fractionation relative to dissolved inorganic carbon sources. This fractionation (εp) has been employed as proxy for paleo-pCO2. Yet, culture experiments indicate this CO2-dependent εp is highly specific at genus and even species lev...

We investigate if the commonly neglected riverine detrital carbonate fluxes might reconciliate several chemical mass balances of the global ocean. Particulate inorganic carbon (PIC) concentrations in riverine suspended sediments, that is, carbon contained by these detrital carbonate minerals, were quantified at the basin and global scale. Our appro...

It has been hypothesized that global temperature trends are tightly linked to tropical thermocline depth, and that thermocline shoaling played a crucial role in the intensification of late Pliocene Northern Hemisphere glaciation. The Pliocene thermocline evolution in the Pacific Ocean is well documented and supports this hypothesis, but thermocline...

One of the great challenges in biogeochemical research over the past half a century has been to quantify and understand the mechanisms underlying stable carbon isotope fractionation (εp) in phytoplankton in response to changing pCO2. Partly, this interest is grounded in the use of fossil photosynthetic organism remains as a proxy for past atmospher...

The Paleocene‐Eocene Thermal Maximum (PETM) is recognized globally by a negative excursion in stable carbon isotope ratios (δ¹³C) in sedimentary records, termed the carbon isotope excursion (CIE). Based on the CIE, the cause, duration, and mechanisms of recovery of the event have been assessed. Here, we focus on the role of increased organic carbon...

Some lipid‐biomarker‐based sea surface temperature (SST) proxies applied in the modern Mediterranean Sea exhibit large offsets from expected values, generating uncertainties in climate reconstructions. Lateral transport of proxy carriers along ocean currents prior to burial can contribute to this offset between reconstructed and expected SSTs. We p...

Oceanic Anoxic Event 2 (ca. 94 Ma; OAE2) was one of the largest Mesozoic carbon cycle perturbations, but associated carbon emissions, primarily from the Caribbean large igneous province (LIP) and marine burial fluxes, are poorly constrained. Here, we use the carbon cycle box model LOSCAR-P to quantify the role of LIP volcanism and enhanced marine o...

Antarctica underwent a complex evolution over the course of the Cenozoic, which influenced the history of the Earth’s climate system. The Eocene-Oligocene boundary is a divide of this history when the ice-free ‘greenhouse world’ transitioned to the ‘icehouse’ with the glaciation of Antarctica. Prior to this, Antarctica experienced warm climates, pe...

Rivers form a crucial part in the global carbon cycle by transferring terrestrial organic carbon (TerrOC) from land to the coastal zone. Upon burial in marine sediments, TerrOC may be a significant long-term carbon sink, depending on the composition and properties of this organic material. However, much remains unknown about the dispersal of the di...

Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by c...

TEX86 is a paleothermometer based on Thaumarcheotal glycerol dialkyl glycerol tetraether (GDGT) lipids and is one of the most frequently used proxies for sea-surface temperature (SST) in warmer-than-present climates. However, the calibration of TEX86 to SST is controversial because its correlation to SST is not significantly stronger than that to d...

Rivers transport dissolved and solid loads from terrestrial realms to the oceans and between inland reservoirs, representing major mass fluxes on Earth's surface. The composition of river water and sediment provides clues to a plethora of Earth and environmental processes, including weathering, erosion, nutrient and carbon cycling, environmental po...

It has been hypothesized that global temperature trends are tightly linked to tropical thermocline depth, and that thermocline shoaling played a crucial role in the intensification of late Pliocene northern hemisphere glaciation. The Pliocene thermocline evolution in the Pacific Ocean is well documented and supports this hypothesis, but thermocline...

The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for the Cenozoic development of the Antarctic Circumpolar Current (ACC). Particularly the tectonic complexity of Drake Passage has hampered the exact dating of the opening and deepening phases, and the consequential onset of throughflow of th...

The fractional abundance of branched glycerol dialkyl glycerol tetraether (brGDGT) membrane lipids in coastal marine sediments has been posited as a proxy for the reconstruction of terrestrial temperatures on the nearby land, based on the assumption that they are produced in soils and delivered to the marine realm by rivers following erosion. Here,...

Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (sw) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by c...

Rivers transport dissolved and solid loads from terrestrial realms to the oceans and between inland reservoirs, representing major mass fluxes on Earth's surface. The composition of river water and sediment provides clues to a plethora of earth and environmental processes, including weathering, erosion, nutrient and carbon cycling, environmental po...

The Middle Eocene Climatic Optimum (MECO), a ∼500kyr episode of global warming that initiated at ∼ 40.5 Ma, is postulated to be driven by a net increase in volcanic carbon input, but a direct source has not been identified. Here we show, based on new and previously published radiometric ages of volcanic rocks, that the interval spanning the MECO co...

Dissolved oceanic CO2 concentrations are rising as result of increasing atmospheric partial pressure of CO2 (pCO2), which has large consequences for phytoplankton. To test how higher CO2 availability affects different traits of the toxic dinoflagellate Alexandrium ostenfeldii, we exposed three strains of the same population to 400 and 1,000 µatm CO...

GloRiSe, a new global database of river sediment composition, including information on geochemical, mineralogical and trace elements along with detailed meta-data, is introduced. Moreover, a preliminary example for the use of state-of-the-art statistical methods for upscaling the data provided by GloRiSe while maintaining spatial discretization. Us...