Palaeoceanography

  • Article
    | Open Access

    Modelling and sea surface temperature proxy data from the Weddell Sea document a 3–4 °C drop coinciding with the Early Cretaceous Weissert Event. Temperature data worldwide confirm a 3.0 °C global mean surface cooling, equivalent to a ~40% drop in atmospheric pCO2, favouring local polar ice.

    • Liyenne Cavalheiro
    • , Thomas Wagner
    •  & Elisabetta Erba
  • Article
    | Open Access

    The Paleocene–Eocene boundary coincided with runaway global warming possibly analogous to future climate change, but the sources of greenhouse gasses have remained unresolved. Here, the authors reveal volcanism triggered initial warming, and subsequent carbon was released after crossing a tipping point.

    • Sev Kender
    • , Kara Bogus
    •  & Melanie J. Leng
  • Article
    | Open Access

    The North Water polynya is a unique but vulnerable ecosystem, home to Indigenous people and Arctic keystone species. New palaeoecological records from Greenland suggest human abandonment c. 2200–1200 cal yrs BP occurred during climate-forced polynya instability, foreshadowing future ecosystem declines.

    • Sofia Ribeiro
    • , Audrey Limoges
    •  & Thomas A. Davidson
  • Article
    | Open Access

    How sea-level in the western Mediterranean reacts to climate changes is not well known. Here, the authors present a regional reconstruction and show that temperatures influenced sea-level change rates during the Holocene, while recent sea-level rise is happening faster than during any other period of the last 4000 years.

    • Matteo Vacchi
    • , Kristen M. Joyse
    •  & Alessio Rovere
  • Article
    | Open Access

    How the Antarctic Circumpolar Current (ACC) changed on glacial-interglacial time scales is not well known. Here, the authors present a 140,000 year long sediment record from the Drake passage and show both glacial-interglacial as well as millennial-scale variability which are linked to Atlantic variability and marine carbon storage.

    • Shuzhuang Wu
    • , Lester Lembke-Jene
    •  & Gerhard Kuhn
  • Article
    | Open Access

    North Atlantic deep water (NADW) formation influences the climate and carbon cycle, but the contribution of Arctic waters is difficult to constrain. Here the authors use Pa/Th proxy measurements to determine the amount of Arctic Ocean water that flows through the Fram Strait and contributes to NADW.

    • Lauren E. Kipp
    • , Jerry F. McManus
    •  & Markus Kienast
  • Article
    | Open Access

    The configuration of past ice sheets, and therefore sea level, is highly uncertain. Here, the authors provide a global reconstruction of ice sheets for the past 80,000 years that allows to test proxy based sea level reconstructions and helps to reconcile disagreements with sea level changes inferred from models.

    • Evan J. Gowan
    • , Xu Zhang
    •  & Gerrit Lohmann
  • Article
    | Open Access

    The expansion of oceanic anoxia during the Paleocene Eocene Thermal Maximum has important implications for faunal turnover patterns and global biogeochemical cycles. Here the authors use uranium isotopes and a biogeochemical model to suggest that the areal expansion of anoxia must have been limited to 10-fold.

    • Matthew O. Clarkson
    • , Timothy M. Lenton
    •  & Derek Vance
  • Article
    | Open Access

    Some algae produce compounds called alkenones that can reconstruct sea surface temperature through geological time, but in high latitudes unknown species complicate use of this proxy. Here the authors find a lineage of sea ice algae that produces alkenones and can be used as a paleo-sensor for sea ice abundance.

    • Karen Jiaxi Wang
    • , Yongsong Huang
    •  & Patricia Cabedo-Sanz
  • Article
    | Open Access

    How and why the ‘Snowball Earth’ occurred during the Cryogenian period is debated. Here, the authors show that the cryogenian ocean hosted diminished tidal amplitudes and associated energy dissipation rates, reaching 10-50% of today’s rates thus perhaps contributing to prolonged glaciations.

    • J. A. Mattias Green
    • , Hannah S. Davies
    •  & Christopher Scotese
  • Article
    | Open Access

    A Southern Ocean influences on the carbon cycle is considered a key component of deglacial changes. Here, the authors show spatial differences in glacial Southern Ocean carbon storage that dissipated rapidly 14.6 kyr ago, revealing a South Indian Ocean contribution to rapid deglacial atmospheric CO2 increases.

    • Julia Gottschalk
    • , Elisabeth Michel
    •  & Samuel L. Jaccard
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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.
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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