86 results on '"Braddock K. Linsley"'
Search Results
2. Author Correction: Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications
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Braddock K. Linsley, Robert B. Dunbar, Emilie P. Dassié, Neil Tangri, Henry C. Wu, Logan D. Brenner, and Gerard M. Wellington
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Science - Abstract
The original version of the Source Data associated with this Article included an error, in which the ‘Fiji AB d13C-Suess’ data point and the ‘TNI2 d13C-Suess Effect’ data point for the year ‘1950.5’ where incorrectly omitted from the Figure 3 tab. The missing values are ‘−0.24’ and ‘−0.64’, respectively. The HTML has been updated to include a corrected version of Source Data.
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- 2019
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3. Correction: Corrigendum: Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum
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Thomas Felis, Helen V. McGregor, Braddock K. Linsley, Alexander W. Tudhope, Michael K. Gagan, Atsushi Suzuki, Mayuri Inoue, Alexander L. Thomas, Tezer M. Esat, William G. Thompson, Manish Tiwari, Donald C. Potts, Manfred Mudelsee, Yusuke Yokoyama, and Jody M. Webster
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Science - Abstract
Nature Communications 5:4102 doi: (2014); Published 17 June 2014; Updated 15 June 2016 The original version of this Article failed to fully credit the use of the Ocean Data View software in figure 1 and supplementary figures 6 and 7, which appears below: Schlitzer, R., Ocean Data View, http://odv.awi.
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- 2016
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4. Constraints on Marine Isotope Stage 3 and 5 Sea Level From the Flooding History of the Karimata Strait in Indonesia
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Thomas L. Weiss, Braddock K. Linsley, Arnold L. Gordon, Yair Rosenthal, and Stefanie Dannenmann‐Di Palma
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Atmospheric Science ,Paleontology ,Oceanography - Published
- 2022
5. Obliquity-driven subtropical forcing of the thermocline after 240 ka in the southern sector of the Western Pacific Warm Pool
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Jonathan E. Lambert, Braddock K. Linsley, Jordan T. Abell, Samantha C. Bova, Gisela Winckler, Yair Rosenthal, Thomas L. Weiss, and Wei Huang
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Paleontology ,Oceanography ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Published
- 2023
6. Pacific North Equatorial Current bifurcation latitude and Kuroshio Current shifts since the Last Glacial Maximum inferred from a Sulu Sea thermocline reconstruction
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Braddock K. Linsley, Thomas L. Weiss, and Arnold L. Gordon
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010506 paleontology ,Archeology ,010504 meteorology & atmospheric sciences ,Globorotalia tumida ,01 natural sciences ,Latitude ,Foraminifera ,Quaternary ,Paleoceanography ,Paleoclimatology ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Stable isotopes ,Global and Planetary Change ,biology ,Kuroshio current ,Intertropical Convergence Zone ,Geology ,Last Glacial Maximum ,North equatorial current ,biology.organism_classification ,Equatorial pacific ,Oceanography ,Thermocline reconstructions ,Sulu sea ,Thermocline - Abstract
The meridional migration of the bifurcation latitude of the Pacific North Equatorial Current (NEC) in the western boundary of the tropical Pacific modulates the strength of the Kuroshio Current. Using salinity reanalysis data, we show the NEC bifurcation latitude also acts as the dominant control on thermocline salinity of the Sulu Sea, just west of the Philippine archipelago, by regulating influx of western Pacific thermocline water via the Luzon Strait. We used oxygen isotopes (δ18O) and Mg/Ca in the thermocline-dwelling foraminifera Globorotalia tumida from Sulu Sea sediment core MD97-2141 to determine past thermocline δ18Ow and salinity variability spanning ∼20–5 ka with an average sampling interval of ∼50 years and infer past changes in the NEC bifurcation latitude. Our Sulu Sea thermocline reconstruction reveals high salinity from ∼18.8–15.5 ka, ∼12.2–11.5 ka, and from ∼9.5–8.5 ka indicating the NEC bifurcation latitude was shifted north and the Kuroshio was weak at those times. Low Sulu Sea thermocline salinity from ∼13.0–12.4 ka, ∼11.5–10.9 ka, and from ∼8.5 ka until the end of the record at ∼5.6 ka indicates the NEC bifurcation latitude was shifted south and the Kuroshio Current was relatively strong. Comparison to other paleoclimate records suggests the observed northward (southward) shifts of the NEC bifurcation latitude were driven by southward (northward) shifts of the Indo-Pacific ITCZ, consistent with modern mechanisms controlling interannual NEC bifurcation variability. The NEC bifurcation latitude shifts likely modulated northward energy transport via the Kuroshio Current and the mean temperature and salinity of the Indonesian Throughflow.
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- 2021
7. Has Nitrogen Supply to Coral Reefs in the South Pacific Ocean Changed Over the Past 50 Thousand Years?
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Quan Hua, Benjamin O. Shepherd, Janice M. Lough, Dirk V. Erler, Luke D. Nothdurft, and Braddock K. Linsley
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Marine conservation ,Tropical pacific ,Atmospheric Science ,geography ,geography.geographical_feature_category ,Coral ,Paleontology ,Coral reef ,Oceanography ,Archaeology ,Pacific ocean ,law.invention ,law ,Christian ministry ,Radiocarbon dating ,Nuclear science - Abstract
This work was funded by the Australian Pacific Science Foundation (APSF14_5 to D. V. Erler and S. R. Scheffers). We thank J. Riekenberg (SCU) for laboratory assistance, S. R. Scheffers (SCU) for assistance with coral collection, and D. Solomona for field support (Ministry of Marine Resources, Cook Islands). AMS radiocarbon dating was supported by the Australian Institute of Nuclear Science and Engineering (AINSE) grant (ALNGRA 15031). We acknowledge the financial support from the Australian Government for the Centre for Accelerator Science at ANSTO through the National Collaborative Research Infrastructure Strategy (NCRIS). Fossil coral nitrogen and oxygen isotopic data are available as in the supporting information.
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- 2019
8. ENSO's Shrinking Twentieth‐Century Footprint Revealed in a Half‐Millennium Coral Core From the South Pacific Convergence Zone
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Neil Tangri, D. M. Mucciarone, Braddock K. Linsley, and Robert B. Dunbar
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Coral ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Core (optical fiber) ,Footprint (electronics) ,El Niño Southern Oscillation ,South Pacific convergence zone ,Geology ,0105 earth and related environmental sciences - Published
- 2018
9. Tracking the South Pacific convergence zone variability and recent acidification reconstructed from tropical corals
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Henning Kuhnert, Albert Benthien, Klaus-Uwe Richter, Braddock K. Linsley, Delphine Dissard, Henry C. Wu, Markus Raitzsch, Jelle Bijma, and Sara Todorovic
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Oceanography ,South Pacific convergence zone ,Tracking (particle physics) ,Geology - Abstract
Massive tropical corals represent one of the most important natural archives of modern climate change. Coral based reconstructions give us the possibility to extend the instrumental oceanographic records and observe hydrographic variability on seasonal to interdecadal scales in tropical oceans. South Pacific convergence zone (SPCZ) variability, Interdecadal Pacific Oscillation (IPO) and El Niño-Southern Oscillation (ENSO) events are major drivers of global climate and may exert control on regional CO2 absorption, outgassing and pH variability.Porites sp. corals from Tonga and Rotuma (Fijian dependency) are being analyzed for multi-proxy (e.g. Sr/Ca, δ18O, δ13C, δ11B, B/Ca) reconstructions of sea surface temperature and salinity (SST, SSS) and carbonate chemistry, on a monthly to annual resolution. Preliminary data of the Rotuma Porites sp. coral shows δ18O has been decreasing by 0.004 ‰ per year at the end of the 20th century, suggesting freshening and/or warming of the surface water. In the same period, we observe a δ13C decrease of 0.017 ‰ per year in-line with the anthropogenic CO2 driven Suess effect. Initial results of the δ11B Tonga Porites sp. show high interannual variability, and a strong trend of decrease of -0.0626 ‰ per year in the last five decades of the record (1949-2004) suggesting acidification. The results are in agreement with published coral-based reconstructions from the region.When completed, the new records will facilitate exploring the effects of modern anthropogenic influence on ocean carbonate system and pH variation, and the relationship between them and interannual and decadal-interdecadal climatic fluctuations.
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- 2021
10. Equatorial Pacific bulk 𝛿15N supports a secular increase in subantarctic zone nitrate utilization after the mid-Pleistocene Transition
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Kelly A Gibson, Mina Surprenant, S. C. Bova, Jonathan Lambert, Yair Rosenthal, and Braddock K. Linsley
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chemistry.chemical_compound ,Oceanography ,Nitrate ,chemistry ,Pleistocene ,Geology - Abstract
Pacific-wide measurements of nitrate and its isotopic composition have furthered our understanding of modern subsurface circulation and have revealed basin-scale connections between oceanographic and nitrogen cycle processes. From the Eastern Tropical Pacific (ETP), the isotopic signature of denitrification is spread zonally and meridionally via subsurface currents. From the Pacific sector of the Southern Ocean, Subantarctic Mode Water (SAMW) penetrates to the low latitudes, delivering nitrate (and likely its isotopic signature) to equatorial surface waters via upwelling. These two regional processes combine to inform much of the thermocline nitrogen dynamics of the Pacific. Here, we compare a new 1.4-Myr bulk sediment 𝛿15N record from the New Guinea margin (IODP Site U1486) to other Pacific 𝛿15N records to track Pleistocene changes in denitrification and SAMW properties. Our results highlight a dramatic increasing 𝛿15N trend after the mid-Pleistocene Transition (MPT) at equatorial sites that is not observed at the New Guinea and California margin sites. Strong 41-ky forcing at equatorial sites and little detectable influence from denitrification (counter to larger denitrification signals at margin sites) suggests increasing 𝛿15N within upwelled SAMW. Because the New Guinea and California margin sites are not below equatorial upwelling, thermocline nitrate is less influenced by SAMW, but rather tracks denitrification in the ETP.As equatorial Pacific nitrate utilization has not dramatically increased in the late Pleistocene, an increase in subantarctic zone nitrate utilization is proposed. Initiation of increased nitrate utilization appears to commence near the end of the MPT and accelerate near the Mid-Brunhes Event (~430 ka). The observed southward shift of the polar front at this time (associated with increased sea surface temperature), combined with elevated dust/iron flux, may have contributed to greater nitrate utilization and a more efficient biological pump in the subantarctic zone. Through the production (via denitrification) and sequestration (via nitrate utilization) of greenhouse gases, these biogeochemical processes potentially participated in feedbacks associated with both the MPT and the Mid-Brunhes Event. Until reconstructions of subantarctic zone nitrate are extended beyond the last two glacial cycles, this reconstruction of SAMW properties via equatorial Pacific bulk 𝛿15N may provide the best record of long-term changes in nitrogen dynamics in the subantarctic zone.
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- 2021
11. Coral Record of Younger Dryas Chronozone Warmth on the Great Barrier Reef
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Marc Humblet, Braddock K. Linsley, Donald C. Potts, Stewart Fallon, L. D. Brenner, Mayuri Inoue, Atsushi Suzuki, Alexander W. Tudhope, Manish K. Tiwari, Helen McGregor, Thomas Felis, Michael K. Gagan, Jody M. Webster, Alexander L. Thomas, Yusuke Yokoyama, Tezer M. Esat, and William G. Thompson
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Coral ,Paleontology ,Last Glacial Maximum ,15. Life on land ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Great barrier reef ,Sea surface temperature ,13. Climate action ,Chronozone ,14. Life underwater ,Younger Dryas ,Geology ,0105 earth and related environmental sciences - Abstract
The Great Barrier Reef (GBR) is an internationally recognized and widely studied ecosystem, yet little is known about its sea surface temperature evolution since the Last Glacial Maximum (LGM) (~20 kyr BP). Here, we present the first paleo‐application of Isopora coral‐derived SST calibrations to a suite of 25 previously published fossil Isopora from the central GBR spanning ~25‐11 kyr BP. The resultant multi‐coral Sr/Ca‐ and δ18O‐derived sea surface temperature anomaly (SSTA) histories are placed within the context of published relative sea level, reef sequence and coralgal reef assemblage evolution. Our new calculations indicate SSTs were cooler on average by ~5‐5.5°C at Noggin Pass (~17°S) and ~7‐8°C at Hydrographer's Passage (~20°S) (Sr/Ca‐derived) during the LGM, in line with previous estimates (Felis et al., 2014). We focus on contextualizing the Younger Dryas Chronozone (YDC, ~12.9‐11.7 kyr BP), whose southern hemisphere expression, in particular in Australia, is elusive and poorly constrained. Our record does not indicate cooling during the YDC with near modern temperatures reached during this interval on the GBR, supporting an asymmetric hemispheric presentation of this climate event. Building on a previous study (Felis et al., 2014), these fossil Isopora SSTA data from the GBR provide new insights into the deglacial reef response, with near‐modern warming during the YDC, since the LGM.
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- 2020
12. Equatorial Pacific bulk sediment δ15N supports a secular increase in Southern Ocean nitrate utilization after the mid-Pleistocene Transition
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Jonathan E. Lambert, Kelly A. Gibson, Braddock K. Linsley, Samantha C. Bova, Yair Rosenthal, and Mina Surprenant
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Archeology ,Global and Planetary Change ,Geology ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
13. South Pacific Convergence Zone dynamics, variability and impacts in a changing climate
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Matthew J. Widlansky, Benjamin R. Lintner, Matthieu Lengaigne, Karin van der Wiel, Josephine R. Brown, James A. Renwick, Cyril Dutheil, Braddock K. Linsley, Adrian J. Matthews, School of Earth Sciences [Melbourne], Faculty of Science [Melbourne], University of Melbourne-University of Melbourne, Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers), Joint Institute for Marine and Atmospheric Research (JIMAR), University of Hawai‘i [Mānoa] (UHM), Royal Netherlands Meteorological Institute (KNMI), Processus et interactions de fine échelle océanique (PROTEO), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Centre for Ocean and Atmospheric Sciences [Norwich] (COAS), School of Environmental Sciences [Norwich], University of East Anglia [Norwich] (UEA)-University of East Anglia [Norwich] (UEA), School of Geography, Environment and Earth Sciences [Wellington], Victoria University of Wellington, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Global warming ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,Subtropics ,15. Life on land ,010502 geochemistry & geophysics ,01 natural sciences ,Pollution ,Sea surface temperature ,13. Climate action ,Atmospheric convection ,Climatology ,Tropical climate ,Extratropical cyclone ,Environmental science ,Climate model ,South Pacific convergence zone ,14. Life underwater ,0105 earth and related environmental sciences ,Nature and Landscape Conservation ,Earth-Surface Processes - Abstract
International audience; The South Pacific Convergence Zone (SPCZ) is a diagonal band of intense rainfall and deep atmospheric convection extending from the equator to the subtropical South Pacific. Displacement of the SPCZ causes variability in rainfall, tropical-cyclone activity and sea level that affects South Pacific island populations and surrounding ecosystems. In this Review, we synthesize recent advances in understanding the physical mechanisms responsible for the SPCZ location and orientation, its interactions with the principal drivers of tropical climate variability, regional and global effects of the SPCZ and its response to anthropogenic climate change. Emerging insight is beginning to provide a coherent description of the character and variability of the SPCZ over synoptic, intraseasonal, interannual and longer timescales. For example, the diagonal orientation of the SPCZ and its natural variability are both the result of a subtle chain of interactions between the tropical and extratropical atmosphere, forced and modulated by the underlying sea surface temperature gradients. However, persistent biases in, and deficiencies of, existing models limit confidence in future projections. Improved climate models and new methods for regional modelling might better constrain future SPCZ projections, aiding climate change adaptation and planning among vulnerable South Pacific communities.
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- 2020
14. Preindustrial to modern variability of sea surface temperatures and CO2 uptake in the South Pacific
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Sara Todorovic, Henning Kuhnert, Delphine Dissard, Henry C. Wu, and Braddock K. Linsley
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Oceanography ,Environmental science - Abstract
The modern increase in atmospheric CO2 driven by fossil fuel combustion and land-use change is warming our atmosphere and surface oceans. The absorption of this excess CO2 by the oceans decreases seawater pH in a process known as ocean acidification (OA), which represents a threat to marine ecosystems with adverse impacts on coral health. It is important to understand how modern climate change impacts interannual and interdecadal climatic cycles and atmospheric phenomena which are originating in the Pacific and modulating global climate. There is a scarcity of data necessary to study the impacts of these changes on natural variability on longer timescales. In this study, we present multi-proxy (e.g. Sr/Ca, δ18O, δ13C, B/Ca) reconstructions of sea surface temperature (SST), surface seawater carbonate chemistry, with implications for pH variability of the South Pacific back to preindustrial times. This region of the Pacific is interesting for tracking the development of OA because of the well-constrained interannual to interdecadal SST and SSS variability from existing coral-based reconstructions. Massive corals (Porites sp.) from Rotuma and Tonga will be analyzed to extend the currently available SST reconstructions and expand the spatio-temporal coverage beyond the instrumental records. New monthly-resolved SST records will provide larger analyses exploring the influence of interannual and decadal-interdecadal climatic fluctuations on CO2 absorption and pH variation. We aim to quantify the anthropogenic impact on SST, pH and the ocean carbonate system to achieve a better understanding of the status in the South Pacific under open ocean conditions.
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- 2020
15. Coral Skeletons Record Increasing Agriculture‐Related Groundwater Nitrogen Inputs to a South Pacific Reef Over the Past Century
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Braddock K. Linsley, Neal E. Cantin, Dirk V. Erler, Janice M. Lough, and Benjamin O. Shepherd
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Delta ,010504 meteorology & atmospheric sciences ,Coral ,Aquifer ,010502 geochemistry & geophysics ,01 natural sciences ,14. Life underwater ,Reef ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,business.industry ,fungi ,technology, industry, and agriculture ,social sciences ,Coral reef ,biochemical phenomena, metabolism, and nutrition ,Geophysics ,Tropical islands ,Oceanography ,Agriculture ,population characteristics ,General Earth and Planetary Sciences ,Environmental science ,business ,Groundwater - Abstract
Anthropogenic activity on tropical islands has been linked with nitrogen (N) contamination of groundwater and subsequent coral reef health decline. However, identifying the temporal patterns of groundwater N contamination has proven difficult because of an absence of long-term records. Here we use delta N-15 in coral skeleton organic material (CS-delta N-15) to reconstruct historical patterns of groundwater N discharge to a coral reef system at Rarotonga in the Cook Islands in the South Pacific. Analysis of coral skeletal material dating back to 1880 CE clearly shows that the delta N-15 of N available in the reef environment around Rarotonga increased between 1980 and 2000. We propose that rapid agricultural development in the Cook Islands between 1960 and 1985 increased aquifer N concentrations leading to the elevated delta N-15 of groundwater NO3-. The discharge of this groundwater N appears to have continued for at least 15 years after the cessation of the agricultural boom. This has important implications for the management of groundwater contamination on low-lying tropical islands.
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- 2018
16. Intermediate-water dynamics and ocean ventilation effects on the Indonesian Throughflow during the past 15,000 years: Ostracod evidence
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Moriaki Yasuhara, Yair Rosenthal, Hokuto Iwatani, and Braddock K. Linsley
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Throughflow ,010504 meteorology & atmospheric sciences ,biology ,Geology ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,language.human_language ,law.invention ,Indonesian ,Water dynamics ,Oceanography ,law ,Ostracod ,Ventilation (architecture) ,language ,0105 earth and related environmental sciences - Published
- 2018
17. Abrupt Northward Shift of SPCZ position in the late-1920s Indicates Coordinated Atlantic and Pacific ITCZ Change
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Emilie Pauline Dassié, Robert B. Dunbar, Braddock K. Linsley, Donna Lee, and Neil Tangri
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0301 basic medicine ,03 medical and health sciences ,030104 developmental biology ,Position (vector) ,Intertropical Convergence Zone ,Climatology ,Geology - Published
- 2017
18. Examining the utility of coral Ba/Ca as a proxy for river discharge and hydroclimate variability at Coiba Island, Gulf of Chirquí, Panamá
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Braddock K. Linsley, L. D. Brenner, and Robert B. Dunbar
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010504 meteorology & atmospheric sciences ,Panama ,Coral ,Porites ,Aquatic Science ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Rivers ,medicine ,Animals ,Seawater ,Precipitation ,0105 earth and related environmental sciences ,El Nino-Southern Oscillation ,Islands ,biology ,Discharge ,Intertropical Convergence Zone ,Seasonality ,Anthozoa ,medicine.disease ,biology.organism_classification ,Pollution ,Droughts ,Barium ,Calcium ,Seasons ,Geology ,Environmental Monitoring - Abstract
Panama's extreme hydroclimate seasonality is driven by Intertropical Convergence Zone rainfall and resulting runoff. River discharge (Q) carries terrestrially-derived barium to coastal waters that can be recorded in coral. We present a Ba/Ca record (1996–1917) generated from a Porites coral colony in the Gulf of Chiriqui near Coiba Island (Panama) to understand regional hydroclimate. Here coral Ba/Ca is correlated to instrumental Q (R = 0.67, p
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- 2017
19. A modern Sr/Ca‐ δ 18 O‐sea surface temperature calibration for Isopora corals on the Great Barrier Reef
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Braddock K. Linsley, Donald C. Potts, and L. D. Brenner
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010504 meteorology & atmospheric sciences ,Calibration (statistics) ,δ18O ,Stable isotope ratio ,Coral ,Paleontology ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Great barrier reef ,Paleothermometer ,Sea surface temperature ,Geology ,0105 earth and related environmental sciences - Published
- 2017
20. SPCZ zonal events and downstream influence on surface ocean conditions in the Indonesian Throughflow region
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Braddock K. Linsley, Arnold L. Gordon, Michael D. Moore, Henry C. Wu, Tim Rixen, and Christopher D. Charles
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Throughflow ,010504 meteorology & atmospheric sciences ,δ18O ,Coral ,Equator ,Ocean current ,010502 geochemistry & geophysics ,01 natural sciences ,Boundary current ,Geophysics ,Oceanography ,13. Climate action ,Climatology ,General Earth and Planetary Sciences ,South Pacific convergence zone ,14. Life underwater ,Geology ,0105 earth and related environmental sciences ,Teleconnection - Abstract
Seasonal surface freshening of the Makassar Strait, the main conduit of the Indonesian Throughflow (ITF), is a key factor controlling the ITF. Here we present a 262 year reconstruction of seasonal sea-surface-salinity variability from 1742 to 2004 Common Era by using coral δ18O records from the central Makassar Strait. Our record reveals persistent seasonal freshening and also years with significant truncations of seasonal freshening that correlate exactly with South Pacific Convergence Zone (SPCZ) zonal events >4000 km to the east. During these events, the SPCZ dramatically rotates ~15° north to near the equator and stronger westward flowing South Pacific boundary currents force higher-salinity water through the Makassar Strait in February–May halting the normal seasonal freshening in the strait. By these teleconnections, our Makassar coral δ18O series provides the first record of the recurrence interval of these zonal SPCZ events and demonstrates that they have occurred on a semiregular basis since the mid-1700s.
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- 2017
21. A paleo-perspective on ocean heat content: Lessons from the Holocene and Common Era
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Yair Rosenthal, Audrey Morley, Braddock K. Linsley, and Julie Kalansky
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Archeology ,Global and Planetary Change ,Water mass ,010504 meteorology & atmospheric sciences ,biology ,Thermal reservoir ,Geology ,Radiative forcing ,010502 geochemistry & geophysics ,Energy budget ,biology.organism_classification ,01 natural sciences ,Foraminifera ,Climatology ,Greenhouse gas ,Ocean heat content ,Ecology, Evolution, Behavior and Systematics ,Holocene ,0105 earth and related environmental sciences - Abstract
The ocean constitutes the largest heat reservoir in the Earth's energy budget and thus exerts a major influence on its climate. Instrumental observations show an increase in ocean heat content (OHC) associated with the increase in greenhouse emissions. Here we review proxy records of intermediate water temperatures from sediment cores and corals in the equatorial Pacific and northeastern Atlantic Oceans, spanning 10,000 years beyond the instrumental record. These records suggests that intermediate waters were 1.5–2 °C warmer during the Holocene Thermal Maximum than in the last century. Intermediate water masses cooled by 0.9 °C from the Medieval Climate Anomaly to the Little Ice Age. These changes are significantly larger than the temperature anomalies documented in the instrumental record. The implied large perturbations in OHC and Earth's energy budget are at odds with very small radiative forcing anomalies throughout the Holocene and Common Era. We suggest that even very small radiative perturbations can change the latitudinal temperature gradient and strongly affect prevailing atmospheric wind systems and hence air-sea heat exchange. These dynamic processes provide an efficient mechanism to amplify small changes in insolation into relatively large changes in OHC. Over long time periods the ocean's interior acts like a capacitor and builds up large (positive and negative) heat anomalies that can mitigate or amplify small radiative perturbations as seen in the Holocene trend and Common Era anomalies, respectively. Evidently the ocean's interior is more sensitive to small external forcings than the global surface ocean because of the high sensitivity of heat exchange in the high-latitudes to climate variations.
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- 2017
22. Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications
- Author
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Henry C. Wu, Braddock K. Linsley, Neil Tangri, Emilie Pauline Dassié, Robert B. Dunbar, L. D. Brenner, and Gerard M. Wellington
- Subjects
0301 basic medicine ,Stable isotope analysis ,Science ,Coral ,Porites ,General Physics and Astronomy ,02 engineering and technology ,Article ,General Biochemistry, Genetics and Molecular Biology ,Suess effect ,03 medical and health sciences ,Palaeoceanography ,Paleoceanography ,14. Life underwater ,lcsh:Science ,Author Correction ,Reef ,Sea level ,Marine biology ,geography ,Carbon dioxide in Earth's atmosphere ,Multidisciplinary ,geography.geographical_feature_category ,biology ,Ocean acidification ,General Chemistry ,Biogeochemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,030104 developmental biology ,Oceanography ,13. Climate action ,Environmental science ,lcsh:Q ,0210 nano-technology - Abstract
Although reef coral skeletal carbon isotopes (δ13C) are routinely measured, interpretation remains controversial. Here we show results of a consistent inverse relationship between coral δ13C and skeletal extension rate over the last several centuries in Porites corals at Fiji, Tonga, Rarotonga and American Samoa in the southwest Pacific. Beginning in the 1950s, this relationship breaks down as the atmospheric 13C Suess effect shifts skeletal δ13C > 1.0‰ lower. We also compiled coral δ13C from a global array of sites and find that mean coral δ13C decreases by −1.4‰ for every 5 m increase in water depth (R = 0.68, p, 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.
- Published
- 2019
23. Coral δ18O evidence for Pacific Ocean mediated decadal variability in Panamanian ITCZ rainfall back to the early 1700s
- Author
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L. D. Brenner, Gerard M. Wellington, Robert B. Dunbar, and Braddock K. Linsley
- Subjects
010504 meteorology & atmospheric sciences ,biology ,Intertropical Convergence Zone ,Coral ,Porites ,Paleontology ,Climate change ,010502 geochemistry & geophysics ,Oceanography ,biology.organism_classification ,01 natural sciences ,Sea surface temperature ,Paleoceanography ,Climatology ,Porites lobata ,Ecology, Evolution, Behavior and Systematics ,Pacific decadal oscillation ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
In Central America, seasonal and interannual shifts in the position of the Intertropical Convergence Zone (ITCZ) control the hydrologic budget. To better understand long-term changes in regional ITCZ-driven precipitation we re-examined a coral δ 18 O record from a Porites lobata coral head near Secas Island (Core ID: S1) (7°59′ N, 82°3′ W) in the Gulf of Chiriqui on the Pacific side of Panama. Linsley et al., (1994) originally published the 277-year time series and first described the presence of a narrow-band decadal cycle (period near 9–12 years) in δ 18 O. The original study did not present potential drivers for the decadal cycle, although they ruled out the influence of the sun spot cycle. Our re-analysis of this record supports the original interpretation that coral δ 18 O is largely responding to variations in precipitation and associated river discharge, but with a new proposed mechanism to explain the decadal mode. There is no similar decadal cycle in gridded instrumental sea surface temperature from the area, suggesting that the decadal coral δ 18 O signal results from hydrologic changes that influence coastal δ 18 O seawater . The decadal component in S1 δ 18 O is also coherent with a decadal mode embedded in the Pacific Decadal Oscillation (PDO) Index that we suggest has tropical origins. We speculate that the coral's temporary δ 18 O deviation (1900–1930) in the decadal mode from the corresponding bands in rainfall and the PDO can be ascribed to a weak PDO in addition to local Panama gap wind variability and its effect on moisture transport from the Atlantic to the Pacific. Ultimately, the Secas Island coral δ 18 O series records ITCZ-driven precipitation dictated by both the Atlantic and Pacific basins.
- Published
- 2016
24. Expedition 363 methods
- Author
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Christopher R. Poole, Tiantian Li, Paul Nicholas Pearson, D. K. Kulhanek, Gregory S. Mountain, Jian Xu, Luc Beaufort, N. Meinicke, A. Schmitt, P.P.B. Eichler, Allan Gil Fernando, Y. Zhang, Ana Christina Ravelo, Masanobu Yamamoto, Ann Holbourn, Anna Joy Drury, Haowen Dang, J. B. Wurtzel, T. Dunkley Jones, Tali L. Babila, Braddock K. Linsley, Germain Bayon, Kelly A Gibson, S. C. Bova, Takuya Sagawa, Ivano W Aiello, Yair Rosenthal, Robert G. Hatfield, D. L. Johnson, Yuho Kumagai, J.-H. Chun, and Bradley N. Opdyke
- Subjects
010504 meteorology & atmospheric sciences ,010502 geochemistry & geophysics ,01 natural sciences ,Geology ,0105 earth and related environmental sciences - Published
- 2018
25. Expedition 363 summary
- Author
-
Ann Holbourn, Tali L. Babila, Bradley N. Opdyke, D. K. Kulhanek, P.P.B. Eichler, J. B. Wurtzel, T. Dunkley Jones, Braddock K. Linsley, S. C. Bova, Christopher R. Poole, Ana Christina Ravelo, Haowen Dang, J.-H. Chun, Jian Xu, Luc Beaufort, Anna Joy Drury, Takuya Sagawa, Yuho Kumagai, Masanobu Yamamoto, Kelly A Gibson, Ivano W Aiello, Robert G. Hatfield, A. Schmitt, Paul Nicholas Pearson, N. Meinicke, Y. Zhang, Germain Bayon, Gregory S. Mountain, Allan Gil Fernando, D. L. Johnson, Yair Rosenthal, and Tiantian Li
- Subjects
010504 meteorology & atmospheric sciences ,010502 geochemistry & geophysics ,01 natural sciences ,Geology ,0105 earth and related environmental sciences - Published
- 2018
26. Spatiotemporal Variability of the South Pacific Convergence Zone Fresh Pool Eastern Front from Coral-Derived Surface Salinity Data
- Author
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Emilie Pauline Dassié, Myriam Khodri, Nicolas Lebas, Audrey Hasson, Braddock K. Linsley, Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Océan et variabilité du climat (VARCLIM), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Processus et interactions de fine échelle océanique (PROTEO), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,010502 geochemistry & geophysics ,01 natural sciences ,Interannual variability ,medicine ,South Pacific convergence zone ,14. Life underwater ,Climate variability ,0105 earth and related environmental sciences ,Interdecadal variability ,Interdecadal Pacific Oscillation ,Ocean current ,Pacific decadal oscillation ,Tropical variability ,Seasonality ,medicine.disease ,Salinity ,Ocean dynamics ,13. Climate action ,Climatology ,Spatial variability ,Oceanic variability ,Geology - Abstract
International audience; Direct observations indicate a southeastward expansion of the South Pacific convergence zone (SPCZ) fresh pool and a freshening trend since the 1970s. Understanding decadal and longer-term variability of the SPCZ fresh pool and of the salinity front located at its southeastern margin has been limited by the scarcity of instrumental sea surface salinity (SSS) measurements. This study uses coral δ18O as a proxy for SSS to extend the salinity record back to the 1880s, from three different locations across the SSS front: Fiji, Tonga, and Rarotonga (FTR region). High percentages of observed SSS variance are explained by multicoral δ18O mean composite at each site. At the interannual time scale, the salinity front displacement over the last 200 years follows the El Niño–Southern Oscillation (ENSO) index. The different El Niño flavors are observable in the amplitude of the salinity front interannual displacement. However, no significant changes in either the frequency or the amplitude of its displacements were observed. At longer time scales, the timing and magnitude of the freshening trend vary among sites. The earliest freshening onset of about −0.06 psu decade−1 is detected in Fiji (around 1865), then Rarotonga (around 1939), and Tonga (around 1982). The role of atmospheric freshwater fluxes on SSS variability is evaluated by comparing coral SSS to historical precipitation data. The results suggest that, despite the known influence of the interdecadal Pacific oscillation (IPO) negative phases on increasing atmospheric freshwater fluxes and lowering SSS in the FTR region, ocean dynamics has a dominant influence at decadal time scale and in the onset of freshening trends.
- Published
- 2018
27. Decadal changes in South Pacific sea surface temperatures and the relationship to the Pacific decadal oscillation and upper ocean heat content
- Author
-
Braddock K. Linsley, Henry C. Wu, Daniel P. Schrag, and Emilie Pauline Dassié
- Subjects
Geophysics ,Oceanography ,Climatology ,Coral ,Meridional overturning ,Annual average ,General Earth and Planetary Sciences ,Environmental science ,Climate change ,Ocean heat content ,Little ice age ,Pacific decadal oscillation - Abstract
Decadal changes in Pacific sea surface temperatures (SSTs) and upper ocean heat content (OHC) remain poorly understood. We present an annual average composite coral Sr/Ca-derived SST time series extending back to 1791 from Fiji, Tonga, and Rarotonga (FTR) in the Pacific Decadal Oscillation (PDO) sensitive region of the southwest Pacific. Decadal SST maxima between 1805 and 1830 Common Era (C.E.) indicate unexplained elevated SSTs near the end of the Little Ice Age. The mean period of decadal SST variability in this region has a period near 25 years. Decades of warmer (cooler) FTR SST co-occur with PDO negative (positive) phases since at least ~1930 C.E. and positively correlate with South Pacific OHC (0–700 m). FTR SST is also inversely correlated with decadal changes in equatorial Pacific SST as measured by coral Sr/Ca. Collectively, these results support the fluctuating trade wind-shallow meridional overturning cell mechanism for decadal modulation of Pacific SSTs and OHC.
- Published
- 2015
28. A Fiji multi-coral δ18O composite approach to obtaining a more accurate reconstruction of the last two-centuries of the ocean-climate variability in the South Pacific Convergence Zone region
- Author
-
Henry C. Wu, Thierry Corrège, Guy Cabioch, Steve Howe, Emilie Pauline Dassié, Gavin M. Lemley, and Braddock K. Linsley
- Subjects
biology ,Coral ,Porites ,Paleontology ,Oceanic climate ,Climate change ,Oceanography ,biology.organism_classification ,Sea surface temperature ,Climatology ,Paleoclimatology ,Climate model ,South Pacific convergence zone ,Geology - Abstract
The limited availability of oceanographic data in the tropical Pacific Ocean prior to the satellite era makes coral-based climate reconstructions a key tool for extending the instrumental record back in time, thereby providing a much needed test for climate models and projections. We have generated a unique regional network consisting of five Porites coral δ18O time series from different locations in the Fijian archipelago. Our results indicate that using a minimum of three Porites coral δ18O records from Fiji is statistically sufficient to obtain a reliable signal for climate reconstruction, and that application of an approach used in tree ring studies is a suitable tool to determine this number. The coral δ18O composite indicates that while sea surface temperature (SST) variability is the primary driver of seasonal δ18O variability in these Fiji corals, annual average coral δ18O is more closely correlated to sea surface salinity (SSS) as previously reported. Our results highlight the importance of water mass advection in controlling Fiji coral δ18O and salinity variability at interannual and decadal time scales despite being located in the heavy rainfall region of the South Pacific Convergence Zone (SPCZ). The Fiji δ18O composite presents a secular freshening and warming trend since the 1850s coupled with changes in both interannual (IA) and decadal/interdecadal (D/I) variance. The changes in IA and D/I variance suggest a re-organization of climatic variability in the SPCZ region beginning in the late 1800s to period of a more dominant interannual variability, which could correspond to a southeast expansion of the SPCZ.
- Published
- 2014
29. [Untitled]
- Author
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Patricia Eichler, Niklas Meinicke, Paul Nicholas Pearson, S. C. Bova, Takuya Sagawa, Bradley N. Opdyke, J. B. Wurtzel, Yuho Kumagai, Christopher R. Poole, Haowen Dang, D. L. Johnson, Robert G. Hatfield, D. K. Kulhanek, Masanobu Yamamoto, Tali L. Babila, Kelly A Gibson, Yi Ge Zhang, Anais Schmitt, Ann Holbourn, Braddock K. Linsley, Tom Dunkley Jones, Anna Joy Drury, Ivano W Aiello, Jian Xu, Luc Beaufort, Allan Gil Fernando, Germain Bayon, Jong-Hwa Chun, Gregory S. Mountain, Yair Rosenthal, and Ana Christina Ravelo
- Subjects
Oceanography ,010504 meteorology & atmospheric sciences ,Preliminary report ,Paleoceanography ,International Ocean Discovery Program ,010502 geochemistry & geophysics ,Neogene ,Quaternary ,01 natural sciences ,Western Hemisphere Warm Pool ,Geology ,0105 earth and related environmental sciences - Published
- 2017
30. Investigation of sea surface temperature changes from replicated coral Sr/Ca variations in the eastern equatorial Pacific (Clipperton Atoll) since 1874
- Author
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Daniel P. Schrag, Braddock K. Linsley, Henry C. Wu, Thierry Corrège, and Mélanie Moreau
- Subjects
geography ,Replication method ,geography.geographical_feature_category ,biology ,Coral ,fungi ,Paleontology ,Atoll ,Oceanography ,biology.organism_classification ,Diagenesis ,Sea surface temperature ,El Niño Southern Oscillation ,Porites lobata ,Sea surface salinity ,Ecology, Evolution, Behavior and Systematics ,Geology ,Earth-Surface Processes - Abstract
Sub-seasonally resolved and replicated coral Sr/Ca time series at Clipperton Atoll (10°18′N, 109°13′W) in the eastern Pacific are assessed as a sea surface temperature (SST) proxy in this region with small seasonal SST variability. The composite coral Sr/Ca time series is a partially replicated record of three live and one sub-modern colony of Porites lobata extending back to 1874. Large inter-colony coral Sr/Ca offsets equate to relative SST differences of 0.6 to 4.3 °C and limit the ability to reconstruct absolute SST changes. Moreover, the replication method revealed a 12-year section of growth in one colony where mean Sr/Ca was anomalously low (~ 1 °C higher SST) relative to the other colonies without evidence of diagenesis or other significant skeletal alterations. The presence of this anomalous interval supports the need for multi-coral Sr/Ca replication in specific sites or regions. The Clipperton Composite Sr/Ca anomaly record is significantly coherent (r = 0.71–0.76, p
- Published
- 2014
31. Indonesian vegetation response to changes in rainfall seasonality over the past 25,000 years
- Author
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Andreas Lückge, Sander van der Kaars, Nathalie Dubois, Mahyar Mohtadi, Jessica E. Tierney, Valier Galy, Timothy I. Eglinton, Yair Rosenthal, Delia W Oppo, Braddock K. Linsley, Earth and Climate, and Amsterdam Global Change Institute
- Subjects
Sediment ,Last Glacial Maximum ,Seasonality ,Radiative forcing ,medicine.disease ,language.human_language ,Indonesian ,Vegetation response ,Climatology ,Dry season ,medicine ,language ,population characteristics ,General Earth and Planetary Sciences ,Environmental science ,SDG 14 - Life Below Water ,medicine.symptom ,Vegetation (pathology) ,geographic locations - Abstract
The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years. For example, drier conditions are inferred on Java and Borneo for the period following the end of the Last Glacial Maximum, whereas wetter conditions are reconstructed for northwest Australia. The response of vegetation to these past rainfall variations is poorly constrained. Using a suite of 30 surface marine sediment samples from throughout the Indo-Pacific warm pool, we demonstrate that today the stable isotopic composition of vascular plant fatty acids (13 Cfa) reflects the regional vegetation composition. This in turn is controlled by the seasonality of rainfall consistent with dry season water stress. Applying this proxy in a sediment core from offshore northeast Borneo, we show broadly similar vegetation cover during the Last Glacial Maximum and the Holocene, suggesting that, despite generally drier glacial conditions, there was no pronounced dry season. In contrast, 13Cfa and pollen data from a core off the coast of Sumba indicate an expansion of C 4 herbs during the most recent glaciation, implying enhanced aridity and water stress during the dry season. Holocene vegetation trends are also consistent with a response to dry season water stress. We therefore conclude that vegetation in tropical monsoon regions is susceptible to increases in water stress arising from an enhanced seasonality of rainfall, as has occurred in past decades. © 2014 Macmillan Publishers Limited.
- Published
- 2014
32. Author Correction: Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications
- Author
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Robert B. Dunbar, L. D. Brenner, Emilie Pauline Dassié, Henry C. Wu, Braddock K. Linsley, Neil Tangri, and Gerard M. Wellington
- Subjects
Multidisciplinary ,Source data ,Science ,Coral ,General Physics and Astronomy ,General Chemistry ,Missing data ,General Biochemistry, Genetics and Molecular Biology ,Water depth ,Isotopes of carbon ,lcsh:Q ,Physical geography ,lcsh:Science ,Geology ,Sea level - Abstract
The original version of the Source Data associated with this Article included an error, in which the ‘Fiji AB d13C-Suess’ data point and the ‘TNI2 d13C-Suess Effect’ data point for the year ‘1950.5’ where incorrectly omitted from the Figure 3 tab. The missing values are ‘−0.24’ and ‘−0.64’, respectively. The HTML has been updated to include a corrected version of Source Data.
- Published
- 2019
33. Pacific Ocean Heat Content During the Past 10,000 Years
- Author
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Delia W Oppo, Yair Rosenthal, and Braddock K. Linsley
- Subjects
Salinity ,Water mass ,Hot Temperature ,Pacific Ocean ,Multidisciplinary ,Oceans and Seas ,Global warming ,Physical oceanography ,Global Warming ,Pacific ocean ,Proxy (climate) ,Oceanography ,Paleoclimatology ,Ocean heat content ,Geology ,Holocene - Abstract
Deep Heating Global warming is popularly viewed only as an atmospheric process, when, as shown by marine temperature records covering the last several decades, most heat uptake occurs in the ocean. How did subsurface ocean temperatures vary during past warm and cold intervals? Rosenthal et al. (p. 617 ) present a temperature record of western equatorial Pacific subsurface and intermediate water masses over the past 10,000 years that shows that heat content varied in step with both northern and southern high-latitude oceans. The findings support the view that the Holocene Thermal Maximum, the Medieval Warm Period, and the Little Ice Age were global events, and they provide a long-term perspective for evaluating the role of ocean heat content in various warming scenarios for the future.
- Published
- 2013
34. Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements
- Author
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Jess F. Adkins, Mayuri Inoue, David H. Case, D. J. Sinclair, Kim M. Cobb, Thomas Felis, Henri Wong, Chen-Feng You, Laura F. Robinson, Terrence M. Quinn, Steven L. Goldstein, Dieter Garbe-Schönberg, Hodaka Kawahata, Alexander C. Gagnon, Gangjian Wei, I. S. Nurhati, Peter B deMenocal, Jacek Raddatz, Walter Geibert, Anton Eisenhauer, Eric Douville, Henry C. Wu, Konrad A Hughen, Nicolas Caillon, Wim Boer, Aleksey Sadekov, Ed C Hathorne, Paolo Montagna, Hélène Rebaubier, Robert M. Sherrell, Helen McGregor, Martin Kölling, Ryuji Asami, Florence Le Cornec, Alexander W. Tudhope, and Braddock K. Linsley
- Subjects
Solution composition ,010504 meteorology & atmospheric sciences ,biology ,Aragonite ,Coral ,Fitness for purpose ,Porites ,Analytical chemistry ,Mineralogy ,engineering.material ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Great barrier reef ,Sea surface temperature ,Geophysics ,13. Climate action ,Geochemistry and Petrology ,Reference values ,engineering ,14. Life underwater ,Geology ,0105 earth and related environmental sciences - Abstract
The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twenty-one laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp-1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is
- Published
- 2013
35. Reconstructing the upper water column thermal structure in the Atlantic Ocean
- Author
-
Caroline Cléroux, J. A. Arbuszewski, Peter B deMenocal, and Braddock K. Linsley
- Subjects
education.field_of_study ,biology ,Population ,Paleontology ,Plankton ,Oceanography ,biology.organism_classification ,Foraminifera ,Water column ,Paleoclimatology ,Thermohaline circulation ,education ,Biological oceanography ,Thermocline ,Geology - Abstract
[1] The thermal structure of the upper ocean (0‐1000m) is set by surface heat fluxes, shallow wind-driven circulation, and the deeper thermohaline circulation. Its long-term variability can be reconstructed using deep-dwelling planktonic foraminifera that record subsurface conditions. Here we used six species (Neogloboquadrina dutertrei,Globorotalia tumida, Globorotalia inflata, Globorotalia truncatulinoides, Globorotalia hirsuta, and Globorotalia crassaformis) from 66 core tops along a meridional transect spanning the mid-Atlantic (42°N to 25°S) to develop a method for reconstructing past thermocline conditions. We estimated the calcification depths from ! 18 O measurements and the Mg/Ca-temperature relationships for each species. This systematic strategy over this large latitudinal section reveals distinct populations with different Mg/Ca-temperature relationships for G. inflata, G. truncatulinoides, and G. hirsuta in different areas. The calcification depths do not differ among the different populations, except for G. hirsuta, where the northern population calcifies much shallower than the southern population. N. dutertrei and G. tumida show a remarkably constant calcification depth independent of oceanographic conditions. The deepest dweller, G. crassaformis, apparently calcifies in the oxygen-depleted zone, where it may find refuge from predators and abundant aggregated matter to feed on. We found a good match between its calcification depth and the 3.2ml/l oxygen level. The results of this multispecies, multiproxy study can now be applied down-core to facilitate the reconstruction of open-ocean thermocline changes in the past.
- Published
- 2013
36. Oceanographic variability in the South Pacific Convergence Zone region over the last 210 years from multi-site coral Sr/Ca records
- Author
-
Emilie Pauline Dassié, Peter B deMenocal, Benedetto Schiraldi, Braddock K. Linsley, and Henry C. Wu
- Subjects
Sea surface temperature ,Water mass ,Geophysics ,Oceanography ,Geochemistry and Petrology ,Climatology ,Microatoll ,South Pacific convergence zone ,Westerlies ,Precipitation ,Western Hemisphere Warm Pool ,Geology ,South Pacific Gyre - Abstract
[1] In the South Pacific Convergence Zone (SPCZ), the variability in a sub-seasonally resolved microatoll Porites colony Sr/Ca record from Tonga and a previously published high-resolution record from Fiji are strongly influenced by sea surface temperature (SST) over the calibration period from 1981 to 2004 (R2 = 0.67–0.68). However, the Sr/Ca-derived SST correlation to instrumental SST decreases back in time. The lower frequency secular trend (~1°C) and decadal-scale (~2–3°C) modes in Sr/Ca-derived SST are almost two times larger than that observed in instrumental SST. The coral Sr/Ca records suggest that local effects on SST generate larger amplitude variability than gridded SST products indicate. Reconstructed δ18O of seawater (δ18Osw) at these sites correlate with instrumental sea surface salinity (SSS; r = 0.64–0.67) but not local precipitation (r = −0.10 to −0.22) demonstrating that the advection and mixing of different salinity water masses may be the predominant control on δ18Osw in this region. The Sr/Ca records indicate SST warming over the last 100 years and appears to be related to the expansion of the western Pacific warm pool (WPWP) including an increasing rate of expansion in the last ~20 years. The reconstructed δ18Osw over the last 100 years also shows surface water freshening across the SPCZ. The warming and freshening of the surface ocean in our study area suggests that the SPCZ has been shifting (expanding) southeast, possibly related to the southward shift and intensification of the South Pacific gyre over the last 50 years in response to strengthened westerly winds.
- Published
- 2013
37. The Suess effect in Fiji coral δ13C and its potential as a tracer of anthropogenic CO2 uptake
- Author
-
Braddock K. Linsley, Emilie Pauline Dassié, and Gavin M. Lemley
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Coral ,Porites ,Atmospheric carbon cycle ,Context (language use) ,Skeletal extension rate ,Oceanography ,01 natural sciences ,Carbon cycle ,Suess effect ,Dissolved organic carbon ,Fiji ,14. Life underwater ,Ecology, Evolution, Behavior and Systematics ,Water depth ,0105 earth and related environmental sciences ,Earth-Surface Processes ,biology ,Carbon isotope ,010604 marine biology & hydrobiology ,Paleontology ,biology.organism_classification ,Dissolved inorganic carbon ,13. Climate action ,CO2 ,Surface water ,Geology - Abstract
In the context of increasing anthropogenic CO2 emissions, determining the rate of oceanic CO2 uptake is of high interest. Centennial-scale changes in delta C-13 of the surface water dissolved inorganic carbon (DIC) reservoir have been shown to be influenced by the carbon isotopic composition of atmospheric CO2. However, the availability of direct oceanic delta C-13 measurements is limited and methods for reconstructing past delta C-13 variability of the oceanic DIC are needed. Geochemical reconstructions of DIC variability can help in understanding how the ocean has reacted to historical changes in the carbon cycle. This study explores the potential of using temporal variations in delta C-13 measured in five Fijian Porites corals for reconstructing oceanic delta C-13 variability. A centennial-scale decreasing delta C-13 trend is observed in these Fiji corals. Other studies have linked similar decreasing delta C-13 trends to anthropogenic changes in the atmospheric carbon reservoir (the "C-13 Suess effect"). We conclude that solar irradiance is the factor influencing the delta C-13 cycle on a seasonal scale, however it is not responsible for the centennial-scale decreasing delta C-13 trend. In addition, variations in skeletal extension rate are not found to account for centennial-scale delta C-13 variability in these corals. Rather, we found that water depth at which a Fijian Porites colony calcifies influences both delta C-13 and extension rate mean values. The water depth-delta C-13 relationship induces a dampening effect on the centennial-scale decreasing delta C-13 trend. We removed this "water depth effect" from the 813C composite, resulting in a truer representation of delta C-13 variability of the Fiji surface water DIC (delta C-13(Fiji-DIC)). The centennial-scale trend in this Fiji coral composite delta C-13(Fiji-DIC) time-series shares similarities with atmospheric delta C-13(CO2), implicating the C-13 Suess effect as the source of the this coral delta C-13 trend. Additionally, our study finds that the delta C-13 variability between the atmosphere and the ocean in this region is not synchronous; the coral delta C-13 response is delayed by similar to 10 years. This agrees with the previously established model of isotopic disequilibrium between atmospheric delta C-13(CO2) and oceanic surface water DIC. (c) 2012 Elsevier B.V. All rights reserved.
- Published
- 2013
38. Corrigendum: Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum
- Author
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Mayuri Inoue, Tezer M. Esat, Alexander L. Thomas, Donald C. Potts, Manfred Mudelsee, Helen McGregor, Thomas Felis, William G. Thompson, Michael K. Gagan, Alexander W. Tudhope, Manish K. Tiwari, Jody M. Webster, Yusuke Yokoyama, Atsushi Suzuki, and Braddock K. Linsley
- Subjects
0301 basic medicine ,Multidisciplinary ,Science ,General Physics and Astronomy ,Zonal and meridional ,Last Glacial Maximum ,General Chemistry ,Corrigenda ,General Biochemistry, Genetics and Molecular Biology ,Great barrier reef ,Ocean Data View ,03 medical and health sciences ,Temperature gradient ,030104 developmental biology ,Oceanography ,Geology - Abstract
Tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR), but the role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown. Here we present records of Sr/Ca and δ(18)O for Last Glacial Maximum and deglacial corals that show a considerably steeper meridional SST gradient than the present day in the central GBR. We find a 1-2 °C larger temperature decrease between 17° and 20°S about 20,000 to 13,000 years ago. The result is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current. Our findings indicate that the GBR experienced substantial meridional temperature change during the last deglaciation, and serve to explain anomalous deglacial drying of northeastern Australia. Overall, the GBR developed through significant SST change and may be more resilient than previously thought.
- Published
- 2016
39. Holocene evolution of the Indonesian throughflow and the western Pacific warm pool
- Author
-
Yair Rosenthal, Delia W Oppo, and Braddock K. Linsley
- Subjects
Throughflow ,biology ,biology.organism_classification ,Western Hemisphere Warm Pool ,Foraminifera ,Oceanography ,Climatology ,Tropical climate ,General Earth and Planetary Sciences ,Thermocline ,Holocene ,Pacific decadal oscillation ,Sea level ,Geology - Abstract
High sea surface temperatures in the western Pacific warm pool fuel atmospheric convection and influence tropical climate. This region also hosts the Indonesian throughflow, the network of currents through which surface and thermocline waters are transported from the western equatorial Pacific Ocean into the Indian Ocean. Here we show, using records of the delta O-18 and Mg/Ca of planktonic foraminifera from eight sediment cores, that from about 10,000 to 7,000 years ago, sea surface temperatures in the western sector of the western Pacific warm pool were about 0.5 degrees C higher than during pre-industrial times. We also find that about 9,500 years ago, when the South China and Indonesian seas were connected by rising sea level, surface waters in the Makassar Strait became relatively fresher. We suggest that the permanent reduction of surface salinity initiated the enhanced flow at lower, thermocline depths seen in the modern Indonesian throughflow. However, the uniformly warm sea surface temperatures found upstream and downstream of the Indonesian throughflow indicate that the early Holocene warmth in this region was not directly related to reduced heat transport by the throughflow that may have resulted from surface freshening of the Makassar Strait. Instead, we propose that the elevated temperatures were the result of a westward shift or expansion of the boundaries of the western Pacific warm pool.
- Published
- 2010
40. 2,000-year-long temperature and hydrology reconstructions from the Indo-Pacific warm pool
- Author
-
Braddock K. Linsley, Delia W Oppo, and Yair Rosenthal
- Subjects
Salinity ,Time Factors ,Atmospheric circulation ,Oceans and Seas ,Rain ,India ,Climate change ,Context (language use) ,Oxygen Isotopes ,History, 18th Century ,History, 21st Century ,History, 17th Century ,Animals ,East Asian Monsoon ,Ice Cover ,Seawater ,Water cycle ,Weather ,History, Ancient ,History, 15th Century ,Hydrology ,Tropical Climate ,Pacific Ocean ,Multidisciplinary ,Atmosphere ,Temperature ,Northern Hemisphere ,Records ,History, 19th Century ,Global change ,History, 20th Century ,Plankton ,History, Medieval ,Sea surface temperature ,Oceanography ,History, 16th Century ,Indonesia ,Calibration ,Environmental science ,Seasons - Abstract
Northern Hemisphere surface temperature reconstructions suggest that the late twentieth century was warmer than any other time during the past 500 years and possibly any time during the past 1,300 years (refs 1, 2). These temperature reconstructions are based largely on terrestrial records from extra-tropical or high-elevation sites; however, global average surface temperature changes closely follow those of the global tropics(3), which are 75% ocean. In particular, the tropical Indo-Pacific warm pool (IPWP) represents a major heat reservoir that both influences global atmospheric circulation(4) and responds to remote northern high-latitude forcings(5,6). Here we present a decadally resolved continuous sea surface temperature (SST) reconstruction from the IPWP that spans the past two millennia and overlaps the instrumental record, enabling both a direct comparison of proxy data to the instrumental record and an evaluation of past changes in the context of twentieth century trends. Our record from the Makassar Strait, Indonesia, exhibits trends that are similar to a recent Northern Hemisphere temperature reconstruction(2). Reconstructed SST was, however, within error of modern values from about AD 1000 to AD 1250, towards the end of the Medieval Warm Period. SSTs during the Little Ice Age ( approximately AD 1550-1850) were variable, and similar to 0.5 to 1 degrees C colder than modern values during the coldest intervals. A companion reconstruction of delta O-18 of sea water-a sea surface salinity and hydrology indicator-indicates a tight coupling with the East Asian monsoon system and remote control of IPWP hydrology on centennial-millennial timescales, rather than a dominant influence from local SST variation.
- Published
- 2009
41. Abrupt climate change and collapse of deep-sea ecosystems
- Author
-
Braddock K. Linsley, Moriaki Yasuhara, Hisayo Okahashi, Thomas M. Cronin, and Peter B deMenocal
- Subjects
Multidisciplinary ,Ecology ,Climate ,Ostracoda ,North Atlantic Deep Water ,Climate change ,Labrador Sea Water ,Paleoceanography ,Oceanography ,Benthic zone ,Crustacea ,Physical Sciences ,Deglacial-Holocene ,Abrupt climate change ,Animals ,Seawater ,Younger Dryas ,Macroecology ,Ecosystem ,Holocene ,Geology ,Species diversity - Abstract
We investigated the deep-sea fossil record of benthic ostracodes during periods of rapid climate and oceanographic change over the past 20,000 years in a core from intermediate depth in the northwestern Atlantic. Results show that deep-sea benthic community "collapses" occur with faunal turnover of up to 50% during major climatically driven oceanographic changes. Species diversity as measured by the Shannon-Wiener index falls from 3 to as low as 1.6 during these events. Major disruptions in the benthic communities commenced with Heinrich Event 1, the Inter-Allerød Cold Period (IACP: 13.1 ka), the Younger Dryas (YD: 12.9-11.5 ka), and several Holocene Bond events when changes in deep-water circulation occurred. The largest collapse is associated with the YD/IACP and is characterized by an abrupt two-step decrease in both the upper North Atlantic Deep Water assemblage and species diversity at 13.1 ka and at 12.2 ka. The ostracode fauna at this site did not fully recover until ≈8 ka, with the establishment of Labrador Sea Water ventilation. Ecologically opportunistic slope species prospered during this community collapse. Other abrupt community collapses during the past 20 ka generally correspond to millennial climate events. These results indicate that deep-sea ecosystems are not immune to the effects of rapid climate changes occurring over centuries or less. © 2008 by The National Academy of Sciences of the USA., link_to_subscribed_fulltext
- Published
- 2008
42. Dynamical excitation of the tropical Pacific Ocean and ENSO variability by Little Ice Age cooling
- Author
-
Braddock K. Linsley, Thomas M Marchitto, G. T. Rustic, and Athanasios Koutavas
- Subjects
Ocean dynamics ,Sea surface temperature ,La Niña ,Multidisciplinary ,El Niño Southern Oscillation ,Meteorology ,Anomaly (natural sciences) ,Climatology ,Intertropical Convergence Zone ,Period (geology) ,Geology ,Pacific decadal oscillation - Abstract
East joins West to complete a picture How have eastern equatorial Pacific sea surface temperatures varied over the past 1000 years? Today, the tropical Pacific Ocean has a large influence on global climate, through processes such as El Niño. Researchers would thus like to know how the ocean varied in the past. Although good records exist from the western ocean, the same has not been true for the eastern side. Rustic et al. analyzed marine sediments recovered from near the Galapagos Islands. They conclude that the tropical Pacific Ocean changed state about 500 years ago, near the transition between the warm Medieval Climate Anomaly and the cold Little Ice Age. Science , this issue p. 1537
- Published
- 2015
43. Refining the sampling approach for the massive coral Diploastrea heliopora for δ18O-based paleoclimate applications
- Author
-
Braddock K. Linsley, Emilie Pauline Dassié, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
- Subjects
biology ,δ18O ,Coral ,Porites ,Paleontology ,Sampling (statistics) ,Diploastrea heliopora ,Oceanography ,biology.organism_classification ,Sea surface temperature ,13. Climate action ,[SDU]Sciences of the Universe [physics] ,Paleoclimatology ,Corallite ,14. Life underwater ,Ecology, Evolution, Behavior and Systematics ,Geology ,Earth-Surface Processes - Abstract
Studies on the Indo-Pacific coral Diploastrea have demonstrated that this genera can potentially be used to generate multi-century length climate reconstructions, however some concerns remain regarding sampling protocols. This study further explores the utility of Diploastrea heliopora for paleoclimatic reconstructions by examining δ 18 O along short coral cores of D. heliopora and Porites lutea from Kandavu, Fiji. These results indicate that sampling of the columellar part of the corallite in D. heliopora is optimal to capture the full annual δ 18 O cycle and that bi-monthly (0.5 mm) sampling resolution is the optimal temporal resolution for the Kandavu D. heliopora . Results from Kandavu D. heliopora show high intra-core reproducibility as well as a significant correlation to a δ 18 O record from a nearby Porites colony (monthly resolution: r = 0.71, n = 186, df = 54, p = 0.01; annual resolution: r = 0.59, n = 16, df = 16, p = 0.01). At our Fiji study site, D. heliopora and Porites skeletal δ 18 O have similar sensitivities to sea surface temperature and sea surface salinity, validating the approach of using both coral species to create robust climate reconstructions. These results indicate that microanalyses of the columellar portion of D. heliopora skeleton produce time-series δ 18 O results similar in quality to that extracted from Porites .
- Published
- 2015
44. Late Holocene lake-level fluctuations in Walker Lake, Nevada, USA
- Author
-
Fasong Yuan, Stephen S. Howe, John P. McGeehin, Steve P. Lund, and Braddock K. Linsley
- Subjects
geography ,geography.geographical_feature_category ,biology ,Walker River ,Limnocythere ,Paleontology ,Sediment ,Structural basin ,Oceanography ,biology.organism_classification ,Sink (geography) ,geography.body_of_water ,Paleoclimatology ,Palaeochannel ,Ecology, Evolution, Behavior and Systematics ,Geology ,Holocene ,Earth-Surface Processes - Abstract
Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (χ), total inorganic carbon (TIC), and oxygen isotopic composition (δ 18 O) of carbonate sediments including ostracode shells (Limnocythere ceriotuberosa) from Walker Lake allow us to extend the sediment record of lake-level fluctuations back to 2700 years B.P. There are approximately five major stages over the course of the late Holocene hydrologic evolution in Walker Lake: an early lowstand (N2400 years B.P.), a lakefilling period (∼2400 to ∼1000 years B.P.), a lake-level lowering period during the Medieval Warm Period (MWP) (∼1000 to ∼600 years B.P.), a relatively wet period (∼600 to ∼100 years B.P.), and the anthropogenically induced lake-level lowering period (b100 years B.P.). The most pronounced lowstand of Walker Lake occurred at ∼2400 years B.P., as indicated by the relatively high values of δ 18 O. This is generally in agreement with the previous lower resolution paleoclimate results from Walker Lake, but contrasts with the sediment records from adjacent Pyramid Lake and Siesta Lake. The pronounced lowstand suggests that the Walker River that fills Walker Lake may have partially diverted into the Carson Sink through the Adrian paleochannel between 2700 to 1400 years B.P.
- Published
- 2006
45. Geochemical evidence from corals for changes in the amplitude and spatial pattern of South Pacific interdecadal climate variability over the last 300 years
- Author
-
Daniel P. Schrag, Alexander W. Tudhope, L. Ren, Braddock K. Linsley, Gerard M. Wellington, and M. J. Salinger
- Subjects
Atmospheric Science ,biology ,δ18O ,Coral ,Interdecadal Pacific Oscillation ,Porites ,biology.organism_classification ,Sea surface temperature ,Oceanography ,Geography ,Climatology ,Common spatial pattern ,South Pacific convergence zone ,Pacific decadal oscillation - Abstract
In the Pacific Ocean, the coherent pattern of interdecadal variations in sea surface temperature (SST) over the last ∼100 years has been termed the Interdecadal Pacific Oscillation (IPO). To examine past variations in the IPO we have generated time series of Sr/Ca and oxygen isotopes (δ18O) from South Pacific Porites coral colonies growing at Rarotonga (1997 to 1726) and Fiji (1997 to 1780). At both sites skeletal Sr/Ca is highly correlated with instrumental SST at least back to ∼1970 and δ18O appears to reflect both SST and South Pacific Convergence Zone (SPCZ) effects on seawater δ18O. Comparison of our results to a New Caledonia coral δ18O record and to indices of interdecadal Pacific climate variability demonstrates that these South Pacific corals have accurately recorded twentieth century variations in the IPO and SPCZ. The coral records also indicate that higher amplitude and more spatially coherent IPO-related variability existed from 1880 to 1950 with notably poor between-site correlations in the mid-1800s. These observations suggest that the spatial IPO pattern in South Pacific SST was significantly more complex and/or poorly defined in the mid-1800s compared to that observed in the twentieth century. Comparison with North Pacific IPO indices also indicates that the degree of cross-hemispheric symmetry of interdecadal oceanographic variability has changed over time with a lower correlation between the North and South Pacific in the mid-1800s. This evidence suggests that the spatial pattern of the IPO at least in the South Pacific has varied over the last 300 years, with a major reorganization occurring after ∼1880 A.D.
- Published
- 2004
46. Response of North American Great Basin Lakes to Dansgaard–Oeschger oscillations
- Author
-
Steve P. Lund, Braddock K. Linsley, Robert M. Negrini, Larry Benson, and Mladen Zic
- Subjects
Archeology ,Global and Planetary Change ,Oceanography ,δ18O ,Magnetic signature ,Northern Hemisphere ,Geology ,Glacial period ,Structural basin ,Ecology, Evolution, Behavior and Systematics ,Proxy (climate) - Abstract
We correlate oscillations in the hydrologic and/or cryologic balances of four Great Basin surface-water systems with Dansgaard–Oeschger (D–O) events 2–12. This correlation is relatively strong at the location of the magnetic signature used to link the lake records, but becomes less well constrained with distance/time from the signature. Comparison of proxy glacial and hydrologic records from Owens and Pyramid lakes indicates that Sierran glacial advances occurred during times of relative dryness. If our hypothesized correlation between the lake-based records and the GISP2 δ18O record is correct, it suggests that North Atlantic D–O stades were associated with relatively cold and dry conditions and that interstades were associated with relatively warm and wet conditions throughout the Great Basin between 50,500 and 27,000 GISP2 yr B.P. The Great Basin lacustrine climate records reinforce the hypothesis that D–O events affected the climate throughout much of the Northern Hemisphere during marine isotope stages 2 and 3. However, the absolute phasing between lake-size and ice-core δ18O records remains difficult to determine.
- Published
- 2003
47. Deconvolving the δ18O seawater component from subseasonal coral δ18O and Sr/Ca at Rarotonga in the southwestern subtropical Pacific for the period 1726 to 1997
- Author
-
Daniel P. Schrag, Gerard M. Wellington, Braddock K. Linsley, Lei Ren, and Ove Hoegh-Guldberg
- Subjects
Delta ,Salinity ,Sea surface temperature ,Oceanography ,Geochemistry and Petrology ,δ18O ,Coral ,Antarctic Circumpolar Wave ,Northern Hemisphere ,Seawater ,Geology - Abstract
To reconstruct oceanographic variations in the subtropical South Pacific, 271-year long subseasonal time series of Sr/Ca and delta(18)O were generated from a coral growing at Rarotonga (21.5degreesS, 159.5degreesW). In this case, coral Sr/Ca appears to be an excellent proxy for sea surface temperature (SST) and coral delta(18)O is a function of both SST and seawater delta(18)O composition (delta(18)O(sw)). Here, we focus on extracting the delta(18)O(sw) signal from these proxy records. A method is presented assuming that coral Sr/Ca is solely a function of SST and that coral delta(18)O is a function of both SST and delta(18)O(sw). This method separates the effects of delta(18)O(sw) from SST by breaking the instantaneous changes of coral delta(18)O into separate contributions by instantaneous SST and delta(18)O(sw) changes, respectively. The results show that on average delta(18)O(sw) at Rarotonga explains similar to39% of the variance in delta(18)O and that variations in SST explains the remaining similar to61% of delta(18)O variance. Reconstructed delta(18)O(sw) shows systematic increases in summer months (December-February) consistent with the regional pattern of variations in precipitation and evaporation. The delta(18)O(sw) also shows a positive linear correlation with satellite-derived estimated salinity for the period 1980 to 1997 (r = 0.72). This linear correlation between reconstructed delta(18)O(sw) and salinity makes it possible to use the reconstructed delta(18)O(sw) to estimate the past interannual and decadal salinity changes in this region. Comparisons of coral delta(18)O and delta(18)O(sw) at Rarotonga with the Pacific decadal oscillation index suggest that the decadal and interdecadal salinity and SST variability at Rarotonga appears to be related to basin-scale decadal variability in the Pacific. Copyright (C) 2002 Elsevier Science Ltd.
- Published
- 2003
48. Influence of the Pacific Decadal Oscillation on the climate of the Sierra Nevada, California and Nevada
- Author
-
Scott Stine, Andre Sarna-Wojcicki, Joe Smoot, Larry Benson, Scott Mensing, Steve P. Lund, and Braddock K. Linsley
- Subjects
Oceanography ,Arts and Humanities (miscellaneous) ,Climatology ,Coral ,General Earth and Planetary Sciences ,Subtropics ,Snowpack ,Geology ,Pacific decadal oscillation ,Earth-Surface Processes - Abstract
Mono Lake sediments have recorded five major oscillations in the hydrologic balance between A.D. 1700 and 1941. These oscillations can be correlated with tree-ring-based oscillations in Sierra Nevada snowpack. Comparison of a tree-ring-based reconstruction of the Pacific Decadal Oscillation (PDO) index (D’Arrigo et al., 2001) with a coral-based reconstruction of Subtropical South Pacific sea-surface temperature (Linsley et al., 2000) indicates a high degree of correlation between the two records during the past 300 yr. This suggests that the PDO has been a pan-Pacific phenomena for at least the past few hundred years. Major oscillations in the hydrologic balance of the Sierra Nevada correspond to changes in the sign of the PDO with extreme droughts occurring during PDO maxima. Four droughts centered on A.D. 1710, 1770, 1850, and 1930 indicate PDO-related drought reoccurrence intervals ranging from 60 to 80 yr.
- Published
- 2003
49. East Asian monsoon forcing of suborbital variability in the Sulu Sea during Marine Isotope Stage 3: Link to Northern Hemisphere climate
- Author
-
Stefanie Dannenmann, Delia W Oppo, Yair Rosenthal, Braddock K. Linsley, and Luc Beaufort
- Subjects
Marine isotope stage ,010504 meteorology & atmospheric sciences ,biology ,Intertropical Convergence Zone ,010502 geochemistry & geophysics ,biology.organism_classification ,01 natural sciences ,Western Hemisphere Warm Pool ,Foraminifera ,Geophysics ,Oceanography ,Ice core ,13. Climate action ,Geochemistry and Petrology ,Paleoceanography ,Climatology ,East Asian Monsoon ,14. Life underwater ,Sea level ,Geology ,0105 earth and related environmental sciences - Abstract
[1] We have generated a new high-resolution record of variations in planktonic foraminiferal oxygen isotopes (δ18O) and Mg/Ca from a sediment core (IMAGES 97-2141) in the Sulu Sea located in the Philippine archipelago of western tropical Pacific. This record reveals distinct, suborbital-scale δ18O changes, most notably during Marine Isotope Stage 3 (MIS3) (∼30,000 to 60,000 years B.P.). The amplitudes of these δ18O fluctuations (0.4 to 0.7‰) exceed that which can be attributed to sea level changes and must be due to changes in sea surface conditions. In the same interval, variations in planktonic foraminifera Mg/Ca suggest that suborbital surface ocean temperature variations of 1 to 1.5°C in the Sulu Sea were not in phase with δ18O. Combined, this evidence indicates that the MIS3 millennial δ18O events in the Sulu Sea were primarily the result of changes in surface water salinity, which today is directly related to the East Asian Monsoon (EAM) and its influence on the balance between surface water contributions from the South China Sea and Western Pacific Warm Pool (WPWP). Within dating uncertainties the MIS3 Sulu Sea δ18O suborbital variability indicates that times of fresher surface conditions in the Sulu Sea coincide with similar conditions in the WPWP [Stott et al., 2002] and also with intensifications of the summer EAM as recorded in the U-Th dated Chinese (Hulu Cave) speleothem δ18O record [Wang et al., 2001] and thus by inference with interstadials in the Greenland Ice core records. Combined, these results indicate that pronounced suborbital variability in the summer EAM and Intertropical Convergence Zone (ITCZ) during MIS3 was tightly coupled with climate conditions in the northern high latitudes.
- Published
- 2003
50. Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum
- Author
-
Manish Tiwari, Donald C. Potts, Jody M. Webster, Mayuri Inoue, Manfred Mudelsee, Tezer M. Esat, Michael K. Gagan, William G. Thompson, Alexander L. Thomas, Helen McGregor, Braddock K. Linsley, Thomas Felis, Yusuke Yokoyama, Atsushi Suzuki, and Alexander W. Tudhope
- Subjects
Multidisciplinary ,General Physics and Astronomy ,Last Glacial Maximum ,Zonal and meridional ,General Chemistry ,Subtropics ,Present day ,Biology ,Article ,General Biochemistry, Genetics and Molecular Biology ,Great barrier reef ,Temperature gradient ,Oceanography ,13. Climate action ,Deglaciation ,14. Life underwater ,South Pacific Gyre - Abstract
Tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR), but the role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown. Here we present records of Sr/Ca and δ18O for Last Glacial Maximum and deglacial corals that show a considerably steeper meridional SST gradient than the present day in the central GBR. We find a 1–2 °C larger temperature decrease between 17° and 20°S about 20,000 to 13,000 years ago. The result is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current. Our findings indicate that the GBR experienced substantial meridional temperature change during the last deglaciation, and serve to explain anomalous deglacial drying of northeastern Australia. Overall, the GBR developed through significant SST change and may be more resilient than previously thought., The Great Barrier Reef (GBR) is under threat from rising ocean temperatures, yet its response to past temperature change is poorly known. Felis et al. show that the GBR experienced a much steeper temperature gradient during the last deglaciation, suggesting it may be more resilient than previously thought.
- Published
- 2014
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