Featured
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| Open AccessA circumpolar dust conveyor in the glacial Southern Ocean
Dust deposition brings iron that fuels ocean productivity, a connection impacting climate over geological time. Here the authors use sediment cores to show that in contrast to dynamics today, during the last glacial maximum westerly winds shuttled dust from Australia and South America around Antarctica and into the South Pacific.
- Torben Struve
- , Katharina Pahnke
- & Gisela Winckler
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Article
| Open AccessModulation of late Pleistocene ENSO strength by the tropical Pacific thermocline
How the El Niño Southern Oscillation depends on the background conditions is not well known. Here, the authors present individual foraminifera distributions which show that central Pacific variability is related to the warmth and depth of the thermocline across varying climate background conditions over the past ~285,000 years.
- Gerald T. Rustic
- , Pratigya J. Polissar
- & Sarah M. White
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Article
| Open AccessHigh-latitude biomes and rock weathering mediate climate–carbon cycle feedbacks on eccentricity timescales
Climate and carbon cycle interactions during major Earth system changes through the Cenozoic remain unclear. Here, the authors present a combined δ13C-δ18O megasplice for the last 35 Ma which allows them to identify three marked intervals of distinct climate–carbon cycle interactions.
- David De Vleeschouwer
- , Anna Joy Drury
- & Heiko Pälike
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Article
| Open AccessMagnesium in subaqueous speleothems as a potential palaeotemperature proxy
Few palaeoclimate archives beyond the polar regions preserve continuous and datable paleotemperature proxy time series over multiple glacial-interglacial cycles. Here, the authors show that Mg concentrations in a subaqueous speleothem from an Italian cave track regional sea-surface temperatures over the last 350,000 years.
- Russell Drysdale
- , Isabelle Couchoud
- & Jon Woodhead
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Article
| Open AccessCold spells in the Nordic Seas during the early Eocene Greenhouse
The early Eocene was characterized by exceptionally high global temperatures and no polar ice. Here, clumped isotope paleothermometry of glendonite calcite from the Danish Basin shows that these were formed in waters below 5 °C, indicating that regionalised cool episodes punctuated the background warmth of the early Eocene.
- Madeleine L. Vickers
- , Sabine K. Lengger
- & Christoph Korte
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Article
| Open AccessProxy evidence for state-dependence of climate sensitivity in the Eocene greenhouse
The relationship between atmospheric CO2 and climate during the Eocene greenhouse remains uncertain. Here authors show that Eocene CO2 and climate sensitivity was high during the warmest intervals and declined as global climate cooled, with implications for the Earth’s future warming climate.
- E. Anagnostou
- , E. H. John
- & G. L. Foster
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Article
| Open AccessDual clumped isotope thermometry resolves kinetic biases in carbonate formation temperatures
Some palaeotemperature proxies suffer from inaccuracies related to kinetic fractionations occurring during carbonate mineral growth. Here, the authors show that dual clumped isotope thermometry can identify the origin of these kinetic biases and allows for the reconstruction of accurate environmental temperatures.
- David Bajnai
- , Weifu Guo
- & Jens Fiebig
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Article
| Open AccessCo-evolution of primitive methane-cycling ecosystems and early Earth’s atmosphere and climate
Biology can profoundly influence the planet’s climate, but over Earth’s long history these effects are poorly constrained. Here the authors show that on early Earth, the evolution of microbes producing and consuming methane likely controlled warming and glacial events, and thus Earth’s habitability
- Boris Sauterey
- , Benjamin Charnay
- & Régis Ferrière
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Article
| Open AccessThe role of calcium in regulating marine phosphorus burial and atmospheric oxygenation
Previous work suggests that marine oxygen levels and bioturbation are important factors that shape phosphorus burial and the size of the marine biosphere. Here the authors show that seawater calcium concentration is a key factor in controlling marine P burial, and thus the global oxygen cycle.
- Mingyu Zhao
- , Shuang Zhang
- & Noah Planavsky
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Article
| Open AccessPersistent global marine euxinia in the early Silurian
The Late Ordovician mass extinction has been attributed to extended marine anoxia. Here, the authors use a metal isotope mass balance model and find the marine anoxic event lasted over 3 million years, notably longer than the anoxic event associated with the Permian-Triassic extinction and Cretaceous ocean anoxic events.
- Richard G. Stockey
- , Devon B. Cole
- & Erik A. Sperling
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Article
| Open AccessThe nature of deep overturning and reconfigurations of the silicon cycle across the last deglaciation
Global atmospheric CO2 varies between glacial–interglacial cycles. Here, the authors study these changes using Si records and how the Si flux and ocean circulation changes controlled the global Si distribution across the last deglaciation, based on high-resolution Si-isotope records from the Indian Sector Southern Ocean.
- M. Dumont
- , L. Pichevin
- & R. Ganeshram
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Article
| Open AccessNo detectable Weddell Sea Antarctic Bottom Water export during the Last and Penultimate Glacial Maximum
The Southern Ocean plays a key role in glacial-interglacial transitions and today, Weddell Sea derived Antarctic Bottom Water is one of the most important deep water masses. New records show that in contrast to today, no Weddell Sea water was exported during the last two glacial maxima, providing new insights towards the condition of Antarctic Bottom Water formation in extreme climate states.
- Huang Huang
- , Marcus Gutjahr
- & Gerhard Kuhn
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Article
| Open AccessGlacial–interglacial Nd isotope variability of North Atlantic Deep Water modulated by North American ice sheet
The Nd isotope composition of seawater has been used to reconstruct past changes in the various contributions of different water masses to the deep ocean, with the isotope signatures of endmember water masses generally assumed to have been stable during the Quaternary. Here, the authors show that deep water produced in the North Atlantic had a significantly more radiogenic Nd signature during the Last Glacial Maximum compared to today.
- Ning Zhao
- , Delia W. Oppo
- & Lloyd D. Keigwin
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Article
| Open AccessNew isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation
Earth’s carbon cycle and oceanic magnesium cycle are controlled by processes such as weathering, volcanism and precipitation of carbonates, such as dolomite. Here, the authors contradict the view that modern dolomite formation is rare and suggest instead that dolomite accounts for ~40–60% of the global oceanic Mg output in the last 20 Ma.
- Netta Shalev
- , Tomaso R. R. Bontognali
- & Derek Vance
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Article
| Open AccessAsynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand
The relative contributions of the Greenland and Antarctic Ice Sheets to Last Interglacial sea level rise remain debated, as do the timing and magnitude. Here, data show that the Antarctic Ice Sheet dominated particularly high levels of sea-level rise during the early Last Interglacial.
- Eelco J. Rohling
- , Fiona D. Hibbert
- & Jimin Yu
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Article
| Open AccessConstraining the rise of oxygen with oxygen isotopes
The loss of anomalous sulfur isotope compositions from sedimentary rocks has been considered a symptom of permanent atmospheric oxygenation. Here the authors show sulfur and oxygen isotope evidence from < 2.31 Ga sedimentary barium sulphates (barites) from the Turee Creek Basin, W. Australia, demonstrating the influence of local non-atmospheric processes on anomalous sulfur isotope signals.
- B. A. Killingsworth
- , P. Sansjofre
- & S. V. Lalonde
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Article
| Open AccessMesopelagic fishes dominate otolith record of past two millennia in the Santa Barbara Basin
Little is known about the long-term dynamics of mesopelagic fish despite their large contribution to total fish biomass. Here, the authors analyze the Santa Barbara Basin otolith record and suggest that mesopelagic fish populations were large but fluctuated with surface climate over the last ~2000 years.
- William A. Jones
- & David M. Checkley Jr.
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Article
| Open AccessMiocene restriction of the Pacific-North Atlantic throughflow strengthened Atlantic overturning circulation
During the Miocene, the Central American seaway was not closed, allowing low-salinity Pacific water to potentially weaken the Atlantic circulation. A new, continuous Nd isotope record shows that there was no direct intermediate water mass export from the Caribbean to the Florida Strait and thus, the Atlantic circulation could strengthen.
- Valeriia Kirillova
- , Anne H. Osborne
- & Martin Frank
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Article
| Open AccessArctic closure as a trigger for Atlantic overturning at the Eocene-Oligocene Transition
Proxies of deep circulation suggest that the onset or strengthening of the Atlantic meridional overturning circulation occurred at the Eocene-Oligocene Transition. The authors show, using a paleoclimate model of the late Eocene, that a shift from Pacific to Atlantic overturning can be triggered at this time by closing the Arctic–Atlantic gateway.
- David K. Hutchinson
- , Helen K. Coxall
- & Agatha M. de Boer
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Article
| Open AccessMore efficient North Atlantic carbon pump during the Last Glacial Maximum
Atmospheric CO2 is governed by CO2 gains (e.g., via Southern Ocean outgassing) and losses (e.g., via North Atlantic absorption). Using a novel method to estimate air–sea CO2 exchange signals, the authors show that North Atlantic CO2 absorption became more efficient and contributed to lowering atmospheric CO2 during ice ages.
- J. Yu
- , L. Menviel
- & A. P. Roberts
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Article
| Open AccessCoral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications
Rising anthropogenic CO2 levels in the atmosphere are resulting in ocean acidification which may impact coral growth rates. Here, the authors quantify the relationship between water depth and δ13C compositions of South Pacific corals from the pre-industrial era, and their results should lead to improvements in the precision of sea level reconstructions using fossil corals.
- Braddock K. Linsley
- , Robert B. Dunbar
- & Gerard M. Wellington
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Article
| Open AccessEvidence for a prolonged Permian–Triassic extinction interval from global marine mercury records
Previously, little direct evidence has been found to link large volcanic eruption events with the end-Permian mass extinction. Here, the authors find that mercury enrichment and isotope records in marine sections across the globe can be linked to increased volcanic activity, which resulted in the protracted Permian-Triassic biocrisis
- Jun Shen
- , Jiubin Chen
- & Noah J. Planavsky
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Article
| Open AccessDeep-water circulation changes lead North Atlantic climate during deglaciation
The response time of North Atlantic climate to changes in high-latitude deep-water formation during the last deglaciation is still unclear. Here the authors show that gradual changes in Nordic Seas deep-water circulation systematically lead ahead of abrupt regional climate shifts by ~400 years.
- Francesco Muschitiello
- , William J. D’Andrea
- & Trond M. Dokken
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Article
| Open AccessEnhanced North Pacific deep-ocean stratification by stronger intermediate water formation during Heinrich Stadial 1
The role of the Pacific Ocean during the last deglacial is less well known. Here the authors used a complex Earth System Model and found that enhanced intermediate-to-deep ocean stratification, and an isolated carbon pool in the deep North Pacific during the last deglaciation when considered alongside proxy records.
- X. Gong
- , L. Lembke-Jene
- & X. F. Shi
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Article
| Open AccessLabrador Sea freshening at 8.5 ka BP caused by Hudson Bay Ice Saddle collapse
The exact freshwater scenario that caused the 8.2 ka cold event is still debated. This study presents new evidence for a severe Labrador shelfwater freshening 8500 years ago that was caused by the Hudson Bay Ice Saddle collapse following a warming in subsurface waters.
- Annalena Antonia Lochte
- , Janne Repschläger
- & Ralph Schneider
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Article
| Open AccessMost Earth-surface calcites precipitate out of isotopic equilibrium
Isotopic thermometry of carbonate minerals postulates that their composition reflects thermodynamic equilibrium constants. Here the authors constrain equilibrium relationships between temperature, 18O/16O and clumped isotopes and find that most natural calcites form out of isotopic equilibrium.
- M. Daëron
- , R. N. Drysdale
- & G. Zanchetta
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Article
| Open AccessClosure of the Bering Strait caused Mid-Pleistocene Transition cooling
The causes of Mid-Pleistocene Transition global cooling 1 million years ago are still unknown. Here, the authors find the subarctic North Pacific became stratified during these glaciations due to closure of the Bering Strait, which would have removed CO2 from the atmosphere and caused global cooling.
- Sev Kender
- , Ana Christina Ravelo
- & Ian R. Hall
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Article
| Open AccessMajor intensification of Atlantic overturning circulation at the onset of Paleogene greenhouse warmth
Ocean circulation likely played a major role in past episodes of global warming. Here the authors show that converging neodymium isotope values indicate intensification of the Atlantic overturning circulation at 59 million years ago, which may have contributed to a more efficient distribution of heat over the planet.
- S. J. Batenburg
- , S. Voigt
- & M. Frank
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Article
| Open AccessNeodymium isotope evidence for glacial-interglacial variability of deepwater transit time in the Pacific Ocean
The response of deep Pacific overturning to glacial-interglacial climate change is still debated. Here the authors show a generally faster deep Pacific overturning operated in recent glacial periods based on a novel application of Nd isotopes recorded in foraminifera.
- Rong Hu
- & Alexander M. Piotrowski
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Article
| Open AccessSouthern Hemisphere forcing of South Asian monsoon precipitation over the past ~1 million years
The orbital-scale timing of South Asian monsoon precipitation is poorly understood. Here the authors show that the long held view that precession drove changes in monsoon strength is wrong, and that obliquity and eccentricity played a stronger role.
- D. Gebregiorgis
- , E. C. Hathorne
- & M. Frank
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Article
| Open AccessEnhanced climate instability in the North Atlantic and southern Europe during the Last Interglacial
It is important to establish a baseline for natural climate variability under relatively warm conditions. Here we show that the Last Interglacial in the North Atlantic and southern Europe was characterized by enhanced climate instability relative to the pre-industrial Holocene.
- P. C. Tzedakis
- , R. N. Drysdale
- & G. Zanchetta
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Article
| Open AccessCoupled microbial bloom and oxygenation decline recorded by magnetofossils during the Palaeocene–Eocene Thermal Maximum
Understanding the response of marine productivity and CO2 drawdown to past warming events can provide important insights into the future. Here, the authors use bacterial magnetite nanoparticle fossils to reconstruct nutrient supply and marine deoxygenation during the Palaeocene–Eocene Thermal Maximum.
- Liao Chang
- , Richard J. Harrison
- & Xiang Zhao
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Article
| Open AccessVegetation response to exceptional global warmth during Oceanic Anoxic Event 2
The Cretaceous Oceanic Anoxic Event 2 represents one of the warmest episodes in the last 250 million years. Here, the authors present spore-pollen data and temperature estimates (TEX86) across an expanded stratigraphic section illustrating the dynamic response of vegetation during this exceptionally warm interval.
- Ulrich Heimhofer
- , Nina Wucherpfennig
- & Ariane Kujau
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Article
| Open AccessPrecession-band variance missing from East Asian monsoon runoff
The underlying mechanisms driving the variability of the East Asia Monsoon during the late Pleistocene remain unclear. Here, the authors present a record of local precipitation and runoff from the East Chain Sea, which indicates strong sensitivity to greenhouse gases and high latitude ice sheet forcing.
- S. C. Clemens
- , A. Holbourn
- & B. Fox-Kemper
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Article
| Open AccessPerturbation to the nitrogen cycle during rapid Early Eocene global warming
Studying the PETM, a past period of rapid warming ~56 Ma, could provide insights into ecosystem response under future warming conditions. Here, the authors present stable nitrogen isotope data that reveal a dramatic change in the marine nitrogen cycle and the emergence of anoxic conditions.
- Christopher K. Junium
- , Alexander J. Dickson
- & Benjamin T. Uveges
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Article
| Open AccessAn atmospheric chronology for the glacial-deglacial Eastern Equatorial Pacific
Chronological assumptions in marine sediment records can result in uncertainties in paleoenvironmental reconstructions. Here, using computed tomography to identify in situ woody debris, the authors construct a robust 14C chronology and reassess ventilation ages in the Eastern Equatorial Pacific during the LGM.
- Ning Zhao
- & Lloyd D. Keigwin
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Article
| Open AccessCoherent deglacial changes in western Atlantic Ocean circulation
The exact timing and magnitude of past changes in Atlantic Ocean circulation, and its relation to abrupt climate changes remains elusive. Here, the authors show a spatially coherent picture of western Atlantic circulation changes, which reveals a two-step AMOC slowdown at the beginning of the deglacial period.
- Hong Chin Ng
- , Laura F. Robinson
- & Tianyu Chen
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Correspondence
| Open AccessNo substantial long-term bias in the Cenozoic benthic foraminifera oxygen-isotope record
- David Evans
- , Marcus P. S. Badger
- & James C. Zachos
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Correspondence
| Open AccessReply to 'No substantial long-term bias in the Cenozoic benthic foraminifera oxygen-isotope record'
- S. Bernard
- , D. Daval
- & A. Meibom
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Article
| Open AccessMiddle Eocene greenhouse warming facilitated by diminished weathering feedback
Silicate rock weathering represents a negative feedback mechanism that regulates atmospheric CO2 levels on geological timescales. Here, the authors show that a diminished silicate weathering feedback may have set the stage for greenhouse warming and ocean acidification during the Middle Eocene, ~40 million years ago.
- Robin van der Ploeg
- , David Selby
- & Appy Sluijs
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Article
| Open AccessSurface ocean pH variations since 1689 CE and recent ocean acidification in the tropical South Pacific
Ocean acidification due to the industrial era is a major marine environmental concern, yet little is known on the historical ocean pH changes prior to human influence. Here, Wu et al. show that tropical South Pacific seawater pH is linked to ENSO pacing and has recently been decreasing rapidly.
- Henry C. Wu
- , Delphine Dissard
- & Claire E. Lazareth
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Article
| Open AccessEnhanced ocean-atmosphere carbon partitioning via the carbonate counter pump during the last deglacial
The contribution of the carbonate counter pump (CCP) to the last deglacial atmospheric CO2 rise has yet been largely ignored. Here, the authors show that an increased CCP in the Subantarctic Pacific along with high surface ocean fertility and [CO2aq], contributed in propelling the Earth out of the last ice age.
- Stéphanie Duchamp-Alphonse
- , Giuseppe Siani
- & Samuel L. Jaccard
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Review Article
| Open AccessSpatio-temporal variability of processes across Antarctic ice-bed–ocean interfaces
Understudied in the Antarctic system are the subsurface interfaces between ice-sheet, ocean and geological substrate. Here, the authors review our understanding of these components and propose new avenues of holistic dynamic modeling to achieve a unified understanding of past, present and future polar climate.
- Florence Colleoni
- , Laura De Santis
- & Martin J. Siegert
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Article
| Open AccessBarium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies
Despite the broad use of barium as a proxy for past ocean export production, the underlying mechanisms of barite precipitation remain unknown. Here, the authors show, under experimental conditions, that barium bioaccumulation on bacterially produced biofilms is the crucial step for barite formation.
- Francisca Martinez-Ruiz
- , Fadwa Jroundi
- & María Teresa González-Muñoz
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Article
| Open AccessWarm summers during the Younger Dryas cold reversal
Mechanisms causing the Younger Dryas cold reversal have been questioned by inconsistencies between proxy and modelling results. Here, the authors show that the concept of a strong North Atlantic Ocean cooling event as major driver is consistent with warm European summers caused by intensified atmospheric blocking.
- Frederik Schenk
- , Minna Väliranta
- & Barbara Wohlfarth
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Article
| Open AccessLate Miocene climate cooling and intensification of southeast Asian winter monsoon
The late Miocene period allows investigation of climate-carbon cycle dynamics on a warmer-than-modern Earth. Here, the authors show that changes in the global carbon cycle drove climate cooling, culminating in ephemeral Northern Hemisphere glaciations and intensification of the Asian winter monsoon from 7 to 5.5 Ma.
- Ann E. Holbourn
- , Wolfgang Kuhnt
- & Nils Andersen
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Article
| Open AccessNumerical simulations of a kilometre-thick Arctic ice shelf consistent with ice grounding observations
Ice grounding features discovered in the Arctic Basin, in water depths exceeding 1 km and dated to the penultimate glacial, suggest a past Arctic ice shelf. Here, the authors undertake numerical simulations that shed light on how such an ice shelf could have formed, its dynamics and most likely configuration.
- Edward G. W. Gasson
- , Robert M. DeConto
- & Chris D. Clark
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Article
| Open AccessCoupling of oceanic carbon and nitrogen facilitates spatially resolved quantitative reconstruction of nitrate inventories
Understanding controls on past nitrogen budgets can improve predictions for future global biogeochemical cycling. Here, using foraminiferal pore density and δ13C, the authors present a quantitative record of deglacial nitrate from the intermediate Pacific and infer close coupling between carbon and nitrogen cycles.
- Nicolaas Glock
- , Zeynep Erdem
- & Anton Eisenhauer
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Article
| Open AccessEvidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice
With rapidly disappearing ice, understanding the past behavior of the cryosphere is critical. Here, the authors indicate the initiation and disappearance of glaciation on Greenland and Arctic sea ice coincided in the past, synchronous with Antarctic ice and global ice volume, and a CO2 threshold of ~500 p.p.m.v.
- Aradhna Tripati
- & Dennis Darby