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A well-oxygenated eastern tropical Pacific during the warm Miocene
Analysis of palaeoceanographic proxies sensitive to oxygen-deficient zone extent and intensity show that the eastern tropical Pacific was well oxygenated during the warm Miocene, agreeing with model simulations that suggest that the recent deoxygenation trend may eventually reverse.
- Anya V. Hess
- , Alexandra Auderset
- & Alfredo Martínez-García
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Indian Ocean salinity build-up primes deglacial ocean circulation recovery
Salinity reconstructions show that Indian Ocean surface salinity increased during glacial periods and that the release of this water via the Agulhas Leakage during deglaciation can trigger abrupt changes in the Atlantic Meridional Overturning Circulation.
- Sophie Nuber
- , James W. B. Rae
- & Stephen Barker
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Bipolar impact and phasing of Heinrich-type climate variability
Ice-core data show that extreme iceberg discharge events in the North Atlantic had no detectable impact on Greenland temperatures but are synchronous with abrupt acceleration of Antarctic warming.
- Kaden C. Martin
- , Christo Buizert
- & Todd A. Sowers
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Basin-scale reconstruction of euxinia and Late Devonian mass extinctions
A spatial and temporal compilation of geochemical data documents a stepwise transgression of toxic euxinic waters into shallow oceans that drove a series of Late Devonian extinction events.
- Swapan K. Sahoo
- , Geoffrey J. Gilleaudeau
- & Alan J. Kaufman
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Deglacial increase of seasonal temperature variability in the tropical ocean
Mass spectrometry imaging of long-chain alkenones in sediments from the Cariaco Basin shows that average temperatures remained stable during the Younger Dryas to Holocene transition but seasonality more than doubled and interannual variability intensified.
- Lars Wörmer
- , Jenny Wendt
- & Kai-Uwe Hinrichs
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Volcanic trigger of ocean deoxygenation during Cordilleran ice sheet retreat
Deoxygenation in the North Pacific immediately after the Cordilleran ice sheet retreat was shown to be linked with volcanism, suggesting that coupling between atmosphere, ocean, cryosphere and solid-Earth systems can drive biogeochemical change.
- Jianghui Du
- , Alan C. Mix
- & Sharon
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Warm pool ocean heat content regulates ocean–continent moisture transport
Geochemical proxies from 360,000-year-old sediment cores and numerical simulations are used to show that the upper ocean heat content of the Indo-Pacific Warm Pool greatly affects the Asian monsoon hydroclimate.
- Zhimin Jian
- , Yue Wang
- & Xingxing Wang
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Article
| Open Access
Enhanced ocean oxygenation during Cenozoic warm periods
By using foraminifera-bound nitrogen isotopes, it is shown that, during two warm periods of the Cenozoic, oxygen-deficient zones contracted rather than expanded, suggesting that global warming may not necessarily lead to increased oceanic anoxia.
- Alexandra Auderset
- , Simone Moretti
- & Alfredo Martínez-García
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Continental configuration controls ocean oxygenation during the Phanerozoic
Analysis of a series of Earth system model experiments shows that continental rearrangement during the Phanerozoic had a marked influence on variations in ocean oxygenation, independent of atmospheric pO2.
- Alexandre Pohl
- , Andy Ridgwell
- & Christopher R. Scotese
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Matters Arising |
Concerns of assuming linearity in the reconstruction of thermal maxima
- T. Laepple
- , J. Shakun
- & S. Marcott
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Matters Arising |
Reply to: Concerns of assuming linearity in the reconstruction of thermal maxima
- Samantha Bova
- , Yair Rosenthal
- & Weipeng Zheng
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Matters Arising |
No freshwater-filled glacial Arctic Ocean
- Robert F. Spielhagen
- , Jan C. Scholten
- & Anton Eisenhauer
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Matters Arising |
Reply to: No freshwater-filled glacial Arctic Ocean
- Walter Geibert
- , Jens Matthiessen
- & Ruediger Stein
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Matters Arising |
Non-trivial role of internal climate feedback on interglacial temperature evolution
- Xu Zhang
- & Fahu Chen
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Matters Arising |
Reply to: Non-trivial role of internal climate feedback on interglacial temperature evolution
- Samantha Bova
- , Yair Rosenthal
- & Cheng Zeng
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Cyclic evolution of phytoplankton forced by changes in tropical seasonality
.Morphometric analysis of coccolith assemblages spanning the last 2,800,000 years suggests that the evolution of coccolithophores is linked to seasonality changes, paced by Earth’s orbital eccentricity with implications for the carbon cycle.
- Luc Beaufort
- , Clara T. Bolton
- & Martin Tetard
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Globally resolved surface temperatures since the Last Glacial Maximum
Paleoclimate datasets are integrated with a climate model to reconstruct global surface temperature since the Last Glacial Maximum, showing sustained warming until the mid-Holocene.
- Matthew B. Osman
- , Jessica E. Tierney
- & Christopher J. Poulsen
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Indo-Pacific Walker circulation drove Pleistocene African aridification
A record of flow-speed variations from an ocean core shows that a key component of Indian Ocean circulation rapidly accelerated 2.1 million years ago, coincident with intensification of Pacific Walker circulation.
- H. J. L. van der Lubbe
- , I. R. Hall
- & J. C. A. Joordens
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Pliocene decoupling of equatorial Pacific temperature and pH gradients
New proxy data for ocean pH and an ocean–atmosphere model show that a radically different ocean circulation led to decoupling of ocean productivity and upwelling in the equatorial Pacific Ocean 3–6 million years ago.
- Madison G. Shankle
- , Natalie J. Burls
- & Pincelli M. Hull
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Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf
Unexpected intervals of low 230Th concentration in marine sediment cores are explained by considering that during at least two such periods, the Arctic Ocean and Nordic seas were composed entirely of fresh water and covered by a thick ice shelf.
- Walter Geibert
- , Jens Matthiessen
- & Ruediger Stein
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Seasonal origin of the thermal maxima at the Holocene and the last interglacial
Reanalysis of Holocene sea surface temperature records affirms the role of retreating ice and rising greenhouse gases in driving a steady increase in global temperatures over the past 12,000 years.
- Samantha Bova
- , Yair Rosenthal
- & Mi Yan
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Antarctic icebergs reorganize ocean circulation during Pleistocene glacials
Iceberg-trajectory models along with multi-proxy evidence from sediment cores from the Indian Ocean show that northward shifts in Antarctic iceberg melt redistributed freshwater in the Southern Ocean during the Pleistocene.
- Aidan Starr
- , Ian R. Hall
- & Hucai Zhang
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Poleward and weakened westerlies during Pliocene warmth
Analysis of dust from marine sediments in the North Pacific shows that warm periods during the Pliocene witnessed weaker and more poleward westerlies than during subsequent glacial periods.
- Jordan T. Abell
- , Gisela Winckler
- & Timothy D. Herbert
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Antarctic ice dynamics amplified by Northern Hemisphere sea-level forcing
Changes in Northern Hemisphere ice-sheet size during ice-age cycles enhance the advance and retreat of the grounding line of the Antarctic Ice Sheet, owing to interhemispheric sea-level forcing.
- Natalya Gomez
- , Michael E. Weber
- & Holly K. Han
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Letter |
The amplitude and origin of sea-level variability during the Pliocene epoch
Sea level varied by 13 ± 5 metres on average, but up to 25 metres, over glacial–interglacial cycles during the Pliocene epoch, due to partial collapses of Antarctic Ice Sheets.
- G. R. Grant
- , T. R. Naish
- & M. O. Patterson
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Letter |
Diversity decoupled from ecosystem function and resilience during mass extinction recovery
After the Cretaceous/Palaeogene mass extinction event, nannoplankton communities exhibited volatility for 1.8 million years before a more stable community emerged, coinciding with restoration of the carbon cycle and a fully functioning biological pump between the surface and deep sea.
- Sarah A. Alvarez
- , Samantha J. Gibbs
- & Andy Ridgwell
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Letter |
Constraints on global mean sea level during Pliocene warmth
Using phreatic overgrowths on speleothems, sea level during the mid-Piacenzian Warm Period, which was about two to three degrees Celsius warmer than the pre-industrial period, is shown to have been about 16 metres higher than today.
- Oana A. Dumitru
- , Jacqueline Austermann
- & Bogdan P. Onac
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Letter |
CO2 storage and release in the deep Southern Ocean on millennial to centennial timescales
Analysis of deep-sea coral boron isotope data, as a proxy for pH and thus CO2 chemistry, provides evidence of CO2 storage in the deep Southern Ocean during the last ice age, and its rapid release on millennial to centennial timescales during deglaciation.
- J. W. B. Rae
- , A. Burke
- & B. J. Taylor
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Letter |
Glacial expansion of oxygen-depleted seawater in the eastern tropical Pacific
A downward expansion of oxygen depletion in the eastern Pacific Ocean during the last ice age suggests an increase in the respired carbon reservoir, contributing to the lower levels of atmospheric carbon dioxide during this period.
- Babette A. A. Hoogakker
- , Zunli Lu
- & Eric Galbraith
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Letter |
Rapid glaciation and a two-step sea level plunge into the Last Glacial Maximum
Details of the drops in sea level associated with glaciation during the Last Glacial Maximum are revealed using a coral proxy from the Great Barrier Reef.
- Yusuke Yokoyama
- , Tezer M. Esat
- & Hironobu Kan
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Letter |
North Pacific freshwater events linked to changes in glacial ocean circulation
Sediment-core and modelling analyses suggest that, during distinct cold periods known as Heinrich Stadials, changes in ocean circulation in the North Atlantic triggered discharge of freshwater from the Cordilleran Ice Sheet into the North Pacific.
- E. Maier
- , X. Zhang
- & G. Lohmann
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Letter |
A two-million-year-long hydroclimatic context for hominin evolution in southeastern Africa
A multiple-proxy reconstruction for the catchment of the Limpopo River and of sea surface temperatures in the Indian Ocean provides evidence for hydroclimatic changes that may have been important in hominin evolution.
- Thibaut Caley
- , Thomas Extier
- & Jacques Giraudeau
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Letter |
Synchronous tropical and polar temperature evolution in the Eocene
A 26-million-year record of equatorial sea surface temperatures reveals synchronous changes of tropical and polar temperatures during the Eocene epoch forced by variations in concentrations of atmospheric carbon dioxide, with a constant degree of polar amplification.
- Margot J. Cramwinckel
- , Matthew Huber
- & Appy Sluijs
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Letter |
Rapid recovery of life at ground zero of the end-Cretaceous mass extinction
Micro- and nannofossil, trace fossil and geochemical evidence from the Chicxulub impact crater demonstrates that proximity to the asteroid impact site did not determine rates of recovery of marine ecosystems after the end-Cretaceous mass extinction.
- Christopher M. Lowery
- , Timothy J. Bralower
- & William Zylberman
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Letter |
Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
Palaeoclimate records show that the Atlantic meridional overturning circulation weakened substantially at the end of the Little Ice Age, probably in response to enhanced freshwater fluxes from the Arctic and Nordic seas.
- David J. R. Thornalley
- , Delia W. Oppo
- & Lloyd D. Keigwin
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Article |
Mean global ocean temperatures during the last glacial transition
Noble gases trapped in ice cores are used to show that the mean global ocean temperature increased by 2.6 degrees Celsius over the last glacial transition and is closely correlated with Antarctic temperature.
- Bernhard Bereiter
- , Sarah Shackleton
- & Jeff Severinghaus
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Letter |
A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts
Deep-ocean O2 concentrations over the past 3.5 billion years are estimated using the oxidation state of iron in submarine basalts and indicate that deep-ocean oxygenation occurred in the Phanerozoic.
- Daniel A. Stolper
- & C. Brenhin Keller
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Article |
Abyssal ocean overturning shaped by seafloor distribution
The geometry of the ocean floor sets key regime transitions in the circulation of deep ocean waters.
- C. de Lavergne
- , G. Madec
- & T. J. McDougall
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Letter |
Very large release of mostly volcanic carbon during the Palaeocene–Eocene Thermal Maximum
Boron and carbon isotope data, used in an Earth system model, show that the Palaeocene–Eocene Thermal Maximum was associated with a much greater release of carbon than thought, most probably triggered by volcanism in the North Atlantic.
- Marcus Gutjahr
- , Andy Ridgwell
- & Gavin L. Foster
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Article |
West Antarctic Ice Sheet retreat driven by Holocene warm water incursions
During the early Holocene epoch—and since the 1940s—variations in Southern Hemisphere westerly winds controlled the upwelling of Circumpolar Deep Water and seemingly ice-sheet retreat in West Antarctica.
- Claus-Dieter Hillenbrand
- , James A. Smith
- & Gerhard Kuhn
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Letter |
Theory of chaotic orbital variations confirmed by Cretaceous geological evidence
Cretaceous astrochronologic evidence reveals a resonance transition associated with the orbits of Mars and the Earth, confirming predicted chaotic Solar System behaviour and enabling an improvement in the geological timescale.
- Chao Ma
- , Stephen R. Meyers
- & Bradley B. Sageman
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Letter |
Heinrich events triggered by ocean forcing and modulated by isostatic adjustment
Heinrich events — episodes of massive iceberg discharge from the Laurentide Ice Sheet into the North Atlantic Ocean — are triggered by the incursion of warm ocean waters destabilizing the calving front.
- Jeremy N. Bassis
- , Sierra V. Petersen
- & L. Mac Cathles
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Letter |
Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age
A reconstruction of changes in ocean oxygenation throughout the last glacial cycle shows that respired carbon was removed from the deep Southern Ocean during deglaciation and Antarctic warm events, consistent with a prominent role of reduced iron fertilization and enhanced ocean ventilation, modifying atmospheric carbon dioxide concentrations over the past 80,000 years.
- Samuel L. Jaccard
- , Eric D. Galbraith
- & Robert F. Anderson
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Letter |
No iron fertilization in the equatorial Pacific Ocean during the last ice age
Core isotope measurements in the equatorial Pacific Ocean reveal that although atmospheric dust deposition during the last ice age was higher than today’s, the productivity of the equatorial Pacific Ocean did not increase; this may have been because iron-enabled greater nutrient consumption, mainly in the Southern Ocean, reduced the nutrients available in the equatorial Pacific Ocean, and hence also productivity there.
- K. M. Costa
- , J. F. McManus
- & A. C. Ravelo
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Letter |
North Pacific deglacial hypoxic events linked to abrupt ocean warming
The processes responsible for driving the expansion of the ocean's oxygen minimum zones remain uncertain; here sediment core data from the Gulf of Alaska suggest that reduced oxygen solubility was a result of ocean warming initiating the expansion of the North Pacific oxygen minimum zone, leading to increased marine productivity and carbon export and, in turn, further reductions in dissolved oxygen levels.
- S. K. Praetorius
- , A. C. Mix
- & F. G. Prahl
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Letter |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies
Neodymium isotopes from fossil fish teeth and tectonic reconstructions show that the deep Tasmanian Gateway opened up about 33 million years ago and that the Antarctic Circumpolar Current arose 30 million years ago, when the gateway probably moved into the latitudes of the strong westerly winds.
- Howie D. Scher
- , Joanne M. Whittaker
- & Margaret L. Delaney
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Letter |
Bipolar seesaw control on last interglacial sea level
A synthesis of new and existing data allows Heinrich Stadial 11 (HS11), a prominent Northern Hemisphere cold event, to be linked to the timing of peak sea-level rise during glacial termination T-II, whereas rapid sea-level rise in T-I is shown to clearly post-date Heinrich Stadial 1, so fundamentally different mechanisms seem to be at work during glacial terminations.
- G. Marino
- , E. J. Rohling
- & J. Yu
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Letter |
Icebergs not the trigger for North Atlantic cold events
A delay between surface cooling and the arrival of ice-rafted debris at a site southwest of Iceland over the past four glacial cycles implies that icebergs typically arrived too late to have triggered cooling, although the freshwater derived from melting icebergs may provide a positive feedback for cold stadial conditions.
- Stephen Barker
- , James Chen
- & David Thornalley
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Letter |
Precise interpolar phasing of abrupt climate change during the last ice age
A new ice core from West Antarctica shows that, during the last ice age, abrupt Northern Hemisphere climate variations were followed two centuries later by a response in Antarctica, suggesting an oceanic propagation of the climate signal to the Southern Hemisphere high latitudes.
- Christo Buizert
- , Betty Adrian
- & Thomas E. Woodruff
Five million years of Antarctic Circumpolar Current strength variability