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  • PANGAEA  (55)
  • Nature Publishing Group (NPG)  (3)
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  • 1
    Publication Date: 2012-08-31
    Description: Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palike, Heiko -- Lyle, Mitchell W -- Nishi, Hiroshi -- Raffi, Isabella -- Ridgwell, Andy -- Gamage, Kusali -- Klaus, Adam -- Acton, Gary -- Anderson, Louise -- Backman, Jan -- Baldauf, Jack -- Beltran, Catherine -- Bohaty, Steven M -- Bown, Paul -- Busch, William -- Channell, Jim E T -- Chun, Cecily O J -- Delaney, Margaret -- Dewangan, Pawan -- Dunkley Jones, Tom -- Edgar, Kirsty M -- Evans, Helen -- Fitch, Peter -- Foster, Gavin L -- Gussone, Nikolaus -- Hasegawa, Hitoshi -- Hathorne, Ed C -- Hayashi, Hiroki -- Herrle, Jens O -- Holbourn, Ann -- Hovan, Steve -- Hyeong, Kiseong -- Iijima, Koichi -- Ito, Takashi -- Kamikuri, Shin-ichi -- Kimoto, Katsunori -- Kuroda, Junichiro -- Leon-Rodriguez, Lizette -- Malinverno, Alberto -- Moore, Ted C Jr -- Murphy, Brandon H -- Murphy, Daniel P -- Nakamura, Hideto -- Ogane, Kaoru -- Ohneiser, Christian -- Richter, Carl -- Robinson, Rebecca -- Rohling, Eelco J -- Romero, Oscar -- Sawada, Ken -- Scher, Howie -- Schneider, Leah -- Sluijs, Appy -- Takata, Hiroyuki -- Tian, Jun -- Tsujimoto, Akira -- Wade, Bridget S -- Westerhold, Thomas -- Wilkens, Roy -- Williams, Trevor -- Wilson, Paul A -- Yamamoto, Yuhji -- Yamamoto, Shinya -- Yamazaki, Toshitsugu -- Zeebe, Richard E -- England -- Nature. 2012 Aug 30;488(7413):609-14. doi: 10.1038/nature11360.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK. hpaelike@marum.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22932385" target="_blank"〉PubMed〈/a〉
    Keywords: *Altitude ; Atmosphere/chemistry ; Calcium Carbonate/*analysis ; *Carbon Cycle ; Carbon Dioxide/analysis ; Diatoms/metabolism ; Foraminifera/metabolism ; Geologic Sediments/chemistry ; Global Warming/history/statistics & numerical data ; History, 21st Century ; History, Ancient ; Marine Biology ; Oxygen/metabolism ; Pacific Ocean ; Seawater/*chemistry ; Temperature
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-08-31
    Description: Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wadham, J L -- Arndt, S -- Tulaczyk, S -- Stibal, M -- Tranter, M -- Telling, J -- Lis, G P -- Lawson, E -- Ridgwell, A -- Dubnick, A -- Sharp, M J -- Anesio, A M -- Butler, C E H -- England -- Nature. 2012 Aug 30;488(7413):633-7. doi: 10.1038/nature11374.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK. j.l.wadham@bris.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22932387" target="_blank"〉PubMed〈/a〉
    Keywords: Antarctic Regions ; Feedback ; Gases/analysis/chemistry/metabolism ; Geologic Sediments/*chemistry/microbiology ; Global Warming ; Ice Cover ; Methane/*analysis/biosynthesis/chemistry ; Pressure ; Solubility ; Temperature ; Uncertainty
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2016-04-26
    Description: The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (delta(11)B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anagnostou, Eleni -- John, Eleanor H -- Edgar, Kirsty M -- Foster, Gavin L -- Ridgwell, Andy -- Inglis, Gordon N -- Pancost, Richard D -- Lunt, Daniel J -- Pearson, Paul N -- England -- Nature. 2016 Apr 25;533(7603):380-4. doi: 10.1038/nature17423.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, Southampton SO14 3ZH, UK. ; School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK. ; School of Earth Sciences, Bristol University, Bristol BS8 1RJ, UK. ; School of Geographical Sciences, Bristol University, Bristol BS8 1SS, UK. ; Department of Earth Sciences, University of California, Riverside, California 92521, USA. ; Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK. ; Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27111509" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
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    PANGAEA
    In:  Supplement to: Rae, James W B; Sarnthein, Michael; Foster, Gavin L; Ridgwell, Andy; Grootes, Pieter Meiert; Elliott, Tim (2014): Deep water formation in the North Pacific and deglacial CO2 rise. Paleoceanography, 29(6), 645-667, https://doi.org/10.1002/2013PA002570
    Publication Date: 2023-01-13
    Description: Deep water formation in the North Atlantic and Southern Ocean is widely thought to influence deglacial CO2 rise and climate change; here we suggest that deep water formation in the North Pacific may also play an important role. We present paired radiocarbon and boron isotope data from foraminifera from sediment core MD02-2489 at 3640 m in the North East Pacific. These show a pronounced excursion during Heinrich Stadial 1, with benthic-planktic radiocarbon offsets dropping to ~350 years, accompanied by a decrease in benthic d11B. We suggest this is driven by the onset of deep convection in the North Pacific, which mixes young shallow waters to depth, old deep waters to the surface, and low-pH water from intermediate depths into the deep ocean. This deep water formation event was likely driven by an increase in surface salinity, due to subdued atmospheric/monsoonal freshwater flux during Heinrich Stadial 1. The ability of North Pacific Deep Water (NPDW) formation to explain the excursions seen in our data is demonstrated in a series of experiments with an intermediate complexity Earth system model. These experiments also show that breakdown of stratification in the North Pacific leads to a rapid ~30 ppm increase in atmospheric CO2, along with decreases in atmospheric d13C and D14C, consistent with observations of the early deglaciation. Our inference of deep water formation is based mainly on results from a single sediment core, and our boron isotope data are unavoidably sparse in the key HS1 interval, so this hypothesis merits further testing. However we note that there is independent support for breakdown of stratification in shallower waters during this period, including a minimum in d15N, younging in intermediate water 14C, and regional warming. We also re-evaluate deglacial changes in North Pacific productivity and carbonate preservation in light of our new data, and suggest that the regional pulse of export production observed during the Bølling-Allerød is promoted by relatively stratified conditions, with increased light availability and a shallow, potent nutricline. Overall, our work highlights the potential of NPDW formation to play a significant and hitherto unrealized role in deglacial climate change and CO2 rise.
    Type: Dataset
    Format: application/zip, 7 datasets
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  • 5
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    PANGAEA
    In:  Supplement to: Schmidt, Daniela N; Thomas, Ellen; Authier, Elisabeth; Saunders, David; Ridgwell, Andy (2018): Strategies in times of crisis—insights into the benthic foraminiferal record of the Palaeocene–Eocene Thermal Maximum. Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences, 376(2130), 20170328, https://doi.org/10.1098/rsta.2017.0328
    Publication Date: 2023-01-13
    Description: Climate change is predicted to alter temperature, carbonate chemistry, and oxygen availability in the oceans, which will affect individuals, populations and ecosystems. We use the fossil record of benthic foraminifers to assess developmental impacts in response to environmental changes during the Paleocene Eocene Thermal Maximum (PETM). Using an unprecedented number of µ-Computer Tomography scans, we determine size of the proloculus (first chamber), number of chambers, and final size of two benthic foraminiferal species which survived the extinction at Sites 690 (Atlantic sector, Southern Ocean, paleodepth 1900m), 1210 (central equatorial Pacific, paleodepth 2100m), and 1135 (Indian Ocean sector, Southern Ocean, 600-1000m). The population at shallowest Site 1135 does not show a clear response to the PETM, whereas those at the other sites record reductions in diameter or proloculus size. Temperature was similar at all sites, thus not likely the reason for differences between sites. At Site 1210, small size coincided with higher chamber numbers during the peak event, and may have been caused by a combination of low carbonate ion concentrations and low food supply. Dwarfing at Site 690 occurred at lower chamber numbers, and may have been caused by decreasing carbonate saturation at sufficient food levels to reproduce. Proloculus size varied strongly between sites and through time, suggesting a large influence of environment on both microspheric and megalospheric forms without clear bimodality. The effect of the environmental changes during the PETM was more pronounced at deeper sites, possibly implicating carbonate saturation.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 6
    Publication Date: 2023-06-27
    Keywords: µ-Computer Tomography; 113-690B; 183-1135; 198-1209B; 198-1210; Age, relative; COMPCORE; Composite Core; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Indian Ocean; Joides Resolution; Leg113; Leg183; Leg198; North Pacific Ocean; Nuttallides truempyi, chamber number; Nuttallides truempyi, diameter; Nuttallides truempyi, proloculus volume; Sample code/label; South Atlantic Ocean
    Type: Dataset
    Format: text/tab-separated-values, 1188 data points
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  • 7
    Publication Date: 2023-06-27
    Keywords: µ-Computer Tomography; 113-690B; 183-1135; 198-1209B; 198-1210; Age, relative; COMPCORE; Composite Core; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Indian Ocean; Joides Resolution; Leg113; Leg183; Leg198; North Pacific Ocean; Nuttallides truempyi, chamber number; Nuttallides truempyi, chamber number, standard error; Nuttallides truempyi, diameter; Nuttallides truempyi, diameter, standard error; Nuttallides truempyi, proloculus volume; Nuttallides truempyi, proloculus volume, standard error; Oridorsalis umbonatus, chamber number; Oridorsalis umbonatus, chamber number, standard error; Oridorsalis umbonatus, diameter; Oridorsalis umbonatus, diameter, standard error; Oridorsalis umbonatus, proloculus volume; Oridorsalis umbonatus, proloculus volume, standard error; Sample code/label; South Atlantic Ocean
    Type: Dataset
    Format: text/tab-separated-values, 240 data points
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  • 8
    Publication Date: 2023-06-27
    Keywords: µ-Computer Tomography; 113-690B; 183-1135; 198-1210; Age, relative; COMPCORE; Composite Core; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Indian Ocean; Joides Resolution; Leg113; Leg183; Leg198; North Pacific Ocean; Oridorsalis umbonatus, chamber number; Oridorsalis umbonatus, diameter; Oridorsalis umbonatus, proloculus volume; Sample code/label; South Atlantic Ocean
    Type: Dataset
    Format: text/tab-separated-values, 540 data points
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  • 9
    Publication Date: 2023-06-27
    Keywords: 113-690B; 183-1135; 198-1209B; 198-1210; Age, relative; COMPCORE; Composite Core; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Indian Ocean; Joides Resolution; Leg113; Leg183; Leg198; North Pacific Ocean; Number of specimens; Proportion; Sample code/label; South Atlantic Ocean; Species
    Type: Dataset
    Format: text/tab-separated-values, 174 data points
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  • 10
    Publication Date: 2023-06-27
    Keywords: Age, comment; Calendar age; DEPTH, sediment/rock; Giant piston corer; GPC; Identification; IMAGES VII - WEPAMA; Marion Dufresne (1995); MD022489; MD02-2489; MD122
    Type: Dataset
    Format: text/tab-separated-values, 39 data points
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