1
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Schimmenti D, Marcantonio F, Hayes CT, Hertzberg J, Schmidt M, Sarao J. Insights into the deglacial variability of phytoplankton community structure in the eastern equatorial Pacific Ocean using [ 231Pa/ 230Th]xs and opal-carbonate fluxes. Sci Rep 2022; 12:22258. [PMID: 36564500 PMCID: PMC9789155 DOI: 10.1038/s41598-022-26593-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Fully and accurately reconstructing changes in oceanic productivity and carbon export and their controls is critical to determining the efficiency of the biological pump and its role in the global carbon cycle through time, particularly in modern CO2 source regions like the eastern equatorial Pacific (EEP). Here we present new high-resolution records of sedimentary 230Th-normalized opal and nannofossil carbonate fluxes and [231Pa/230Th]xs ratios from site MV1014-02-17JC in the Panama Basin. We find that, across the last deglaciation, phytoplankton community structure is driven by changing patterns of nutrient (nitrate, iron, and silica) availability which, in turn, are caused by variability in the position of the Intertropical Convergence Zone (ITCZ) and associated changes in biogeochemical cycling and circulation in the Southern Ocean. Our multi-proxy work suggests greater scrutiny is required in the interpretation of common geochemical proxies of productivity and carbon export in the EEP.
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Affiliation(s)
- Danielle Schimmenti
- grid.264756.40000 0004 4687 2082Department of Geology and Geophysics, Texas A&M University, College Station, TX USA
| | - Franco Marcantonio
- grid.264756.40000 0004 4687 2082Department of Geology and Geophysics, Texas A&M University, College Station, TX USA
| | - Christopher T. Hayes
- grid.267193.80000 0001 2295 628XSchool of Ocean Science and Engineering, University of Southern Mississippi, Stennis Space Center, MS USA
| | | | - Matthew Schmidt
- grid.261368.80000 0001 2164 3177Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA USA
| | - John Sarao
- grid.264756.40000 0004 4687 2082Department of Geology and Geophysics, Texas A&M University, College Station, TX USA
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2
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González-Pinilla FJ, Latorre C, Rojas M, Houston J, Rocuant MI, Maldonado A, Santoro CM, Quade J, Betancourt JL. High- and low-latitude forcings drive Atacama Desert rainfall variations over the past 16,000 years. SCIENCE ADVANCES 2021; 7:eabg1333. [PMID: 34533988 PMCID: PMC8448445 DOI: 10.1126/sciadv.abg1333] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
Late Quaternary precipitation dynamics in the central Andes have been linked to both high- and low-latitude atmospheric teleconnections. We use present-day relationships between fecal pellet diameters from ashy chinchilla rats (Abrocoma cinerea) and mean annual rainfall to reconstruct the timing and magnitude of pluvials (wet episodes) spanning the past 16,000 years in the Atacama Desert based on 81 14C-dated A. cinerea paleomiddens. A transient climate simulation shows that pluvials identified at 15.9 to 14.8, 13.0 to 8.6, and 8.1 to 7.6 ka B.P. can be linked to North Atlantic (high-latitude) forcing (e.g., Heinrich Stadial 1, Younger Dryas, and Bond cold events). Holocene pluvials at 5.0 to 4.6, 3.2 to 2.1, and 1.4 to 0.7 ka B.P. are not simulated, implying low-latitude internal variability forcing (i.e., ENSO regime shifts). These results help constrain future central Andean hydroclimatic variability and hold promise for reconstructing past climates from rodent middens in desert ecosystems worldwide.
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Affiliation(s)
- Francisco J. González-Pinilla
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute of Ecology and Biodiversity (IEB), Santiago, Chile
| | - Claudio Latorre
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute of Ecology and Biodiversity (IEB), Santiago, Chile
| | - Maisa Rojas
- Center for Climate and Resilience Research (CR) and Departamento de Geofísica, Universidad de Chile, Santiago, Chile
| | | | - M. Ignacia Rocuant
- Centro UC Desierto de Atacama and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Antonio Maldonado
- Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad de La Serena, La Serena, Chile
- Departamento de Biología Marina, Universidad Católica del Norte, Coquimbo, Chile
| | - Calogero M. Santoro
- Instituto de Alta Investigación (IAI), Universidad de Tarapacá, Arica, Chile
| | - Jay Quade
- Department of Geosciences, The University of Arizona, Tucson, AZ, USA
| | - Julio L. Betancourt
- Scientist Emeritus, U.S. Geological Survey, Science and Decisions Center, Reston, VA, USA
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3
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Seasonal drought events in tropical East Asia over the last 60,000 y. Proc Natl Acad Sci U S A 2020; 117:30988-30992. [PMID: 33229562 DOI: 10.1073/pnas.2013802117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cause of seasonal hydrologic changes in tropical East Asia during interstadial/stadial oscillations of the last glaciation remains controversial. Here, we show seven seasonal drought events that occurred during the relatively warm interstadials by phytolith and pollen records. These events are significantly manifested as high percentages of bilobate phytoliths and are consistent with the large zonal sea-surface temperature (SST) gradient from the western to eastern tropical Pacific, suggesting that the reduction in seasonal precipitation could be interpreted by westward shifts of the western Pacific subtropical high triggered by changes of zonal SST gradient over the tropical Pacific and Hadley circulation in the Northern Hemisphere. Our findings highlight that both zonal and meridional ocean-atmosphere circulations, rather than solely the Intertropical Convergence Zone or El Niño-Southern Oscillation, controlled the hydrologic changes in tropical East Asia during the last glaciation.
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4
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Praetorius SK, Condron A, Mix AC, Walczak MH, McKay JL, Du J. The role of Northeast Pacific meltwater events in deglacial climate change. SCIENCE ADVANCES 2020; 6:eaay2915. [PMID: 32133399 PMCID: PMC7043920 DOI: 10.1126/sciadv.aay2915] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
Columbia River megafloods occurred repeatedly during the last deglaciation, but the impacts of this fresh water on Pacific hydrography are largely unknown. To reconstruct changes in ocean circulation during this period, we used a numerical model to simulate the flow trajectory of Columbia River megafloods and compiled records of sea surface temperature, paleo-salinity, and deep-water radiocarbon from marine sediment cores in the Northeast Pacific. The North Pacific sea surface cooled and freshened during the early deglacial (19.0-16.5 ka) and Younger Dryas (12.9-11.7 ka) intervals, coincident with the appearance of subsurface water masses depleted in radiocarbon relative to the sea surface. We infer that Pacific meltwater fluxes contributed to net Northern Hemisphere cooling prior to North Atlantic Heinrich Events, and again during the Younger Dryas stadial. Abrupt warming in the Northeast Pacific similarly contributed to hemispheric warming during the Bølling and Holocene transitions. These findings underscore the importance of changes in North Pacific freshwater fluxes and circulation in deglacial climate events.
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Affiliation(s)
| | - Alan Condron
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Alan C. Mix
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Maureen H. Walczak
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Jennifer L. McKay
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Jianghui Du
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
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5
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Liu Z, Huang S, Jin Z. A last deglacial climate dataset comprising ice core data, marine data, and stalagmite data. Data Brief 2018; 21:1764-1770. [PMID: 30505913 PMCID: PMC6249515 DOI: 10.1016/j.dib.2018.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/01/2018] [Accepted: 11/01/2018] [Indexed: 11/27/2022] Open
Abstract
In this data article, a dataset of paleoclimatic records ranging from 22 to 9 thousand years before present is reported, which is related to the research article entitled "Breakpoint lead-lag analysis of the last deglacial climate change and atmospheric CO2 concentration on global and hemispheric scales" published in the journal of Quaternary International by Liu et al. (2018). In the dataset, 4 δ18O records derived from Greenlandic ice cores, 2 δD records and 7 δ18O records derived from Antarctic ice cores, 32 UK' 37 records and 26 Mg/Ca records derived from marine deposits, and 17 δ18O records derived from cave stalagmites were collected and collated. General and statistical characteristics of these 88 proxy records are showed here. All of the data are stored in separate Microsoft Excel spreadsheets that are available for researchers.
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Affiliation(s)
- Zhi Liu
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
| | - Shaopeng Huang
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1063, USA
| | - Zhangdong Jin
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China
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6
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Hoogakker BAA, Lu Z, Umling N, Jones L, Zhou X, Rickaby REM, Thunell R, Cartapanis O, Galbraith E. Glacial expansion of oxygen-depleted seawater in the eastern tropical Pacific. Nature 2018; 562:410-413. [PMID: 30333577 DOI: 10.1038/s41586-018-0589-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/13/2018] [Indexed: 11/09/2022]
Abstract
Increased storage of carbon in the oceans has been proposed as a mechanism to explain lower concentrations of atmospheric carbon dioxide during ice ages; however, unequivocal signatures of this storage have not been found1. In seawater, the dissolved gases oxygen and carbon dioxide are linked via the production and decay of organic material, with reconstructions of low oxygen concentrations in the past indicating an increase in biologically mediated carbon storage. Marine sediment proxy records have suggested that oxygen concentrations in the deep ocean were indeed lower during the last ice age, but that near-surface and intermediate waters of the Pacific Ocean-a large fraction of which are poorly oxygenated at present-were generally better oxygenated during the glacial1-3. This vertical opposition could suggest a minimal net basin-integrated change in carbon storage. Here we apply a dual-proxy approach, incorporating qualitative upper-water-column and quantitative bottom-water oxygen reconstructions4,5, to constrain changes in the vertical extent of low-oxygen waters in the eastern tropical Pacific since the last ice age. Our tandem proxy reconstructions provide evidence of a downward expansion of oxygen depletion in the eastern Pacific during the last glacial, with no indication of greater oxygenation in the upper reaches of the water column. We extrapolate our quantitative deep-water oxygen reconstructions to show that the respired carbon reservoir of the glacial Pacific was substantially increased, establishing it as an important component of the coupled mechanism that led to low levels of atmospheric carbon dioxide during the glacial.
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Affiliation(s)
- Babette A A Hoogakker
- The Lyell Centre, Heriot-Watt University, Edinburgh, UK. .,Department of Earth Sciences, University of Oxford, Oxford, UK.
| | - Zunli Lu
- Department of Earth Sciences, Syracuse University, Syracuse, NY, USA. .,State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
| | - Natalie Umling
- School of Earth, Ocean and Environment, University of South Carolina, Columbia, SC, USA
| | - Luke Jones
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - Xiaoli Zhou
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA
| | | | - Robert Thunell
- School of Earth, Ocean and Environment, University of South Carolina, Columbia, SC, USA
| | - Olivier Cartapanis
- University of Bern, Oeschger Centre for Climate Change Research, Bern, Switzerland
| | - Eric Galbraith
- Institut de Ciencia i Tecnologia Ambientals (ICTA) and Department of Mathematics, Universitat Autonoma de Barcelona, Bellaterra, Spain.,ICREA, Barcelona, Spain
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7
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An atmospheric chronology for the glacial-deglacial Eastern Equatorial Pacific. Nat Commun 2018; 9:3077. [PMID: 30082732 PMCID: PMC6079080 DOI: 10.1038/s41467-018-05574-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/16/2018] [Indexed: 11/15/2022] Open
Abstract
Paleoclimate reconstructions are only as good as their chronology. In particular, different chronological assumptions for marine sediment cores can lead to different reconstructions of ocean ventilation age and atmosphere−ocean carbon exchange history. Here we build the first high-resolution chronology that is free of the dating uncertainties common in marine sediment records, based on radiocarbon dating twigs found with computed tomography scans in two cores from the Eastern Equatorial Pacific (EEP). With this accurate chronology, we show that the ventilation ages of the EEP thermocline and intermediate waters were similar to today during the Last Glacial Maximum and deglaciation, in contradiction with previous studies. Our results suggest that the glacial respired carbon pool in the EEP was not significantly older than today, and that the deglacial strengthening of the equatorial Pacific carbon source was probably driven by low-latitude processes rather than an increased subsurface supply of upwelled carbon from high-latitude oceans. Chronological assumptions in marine sediment records can result in uncertainties in paleoenvironmental reconstructions. Here, using computed tomography to identify in situ woody debris, the authors construct a robust 14C chronology and reassess ventilation ages in the Eastern Equatorial Pacific during the LGM.
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8
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Future loss of Arctic sea-ice cover could drive a substantial decrease in California's rainfall. Nat Commun 2017; 8:1947. [PMID: 29209024 PMCID: PMC5717256 DOI: 10.1038/s41467-017-01907-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/24/2017] [Indexed: 11/20/2022] Open
Abstract
From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter storms were steered away from California by a persistent atmospheric ridging system in the North Pacific. Here we identify a new link between Arctic sea-ice loss and the North Pacific geopotential ridge development. In a two-step teleconnection, sea-ice changes lead to reorganization of tropical convection that in turn triggers an anticyclonic response over the North Pacific, resulting in significant drying over California. These findings suggest that the ability of climate models to accurately estimate future precipitation changes over California is also linked to the fidelity with which future sea-ice changes are simulated. We conclude that sea-ice loss of the magnitude expected in the next decades could substantially impact California’s precipitation, thus highlighting another mechanism by which human-caused climate change could exacerbate future California droughts. Persistent atmospheric ridging in the North Pacific steered storms away and led to the California drought of 2012-16. Here the authors use simulations to show that sea-ice changes trigger reorganization of tropical convection resulting in drying over California.
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9
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Asmerom Y, Polyak VJ, Lachniet MS. Extrapolar climate reversal during the last deglaciation. Sci Rep 2017; 7:7157. [PMID: 28769108 PMCID: PMC5541005 DOI: 10.1038/s41598-017-07721-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/10/2017] [Indexed: 11/17/2022] Open
Abstract
Large ocean-atmosphere and hydroclimate changes occurred during the last deglaciation, although the interplay between these changes remains ambiguous. Here, we present a speleothem-based high resolution record of Northern Hemisphere atmospheric temperature driven polar jet variability, which matches the Greenland ice core records for the most of the last glacial period, except during the last deglaciation. Our data, combined with data from across the globe, show a dramatic climate reversal during the last deglaciation, which we refer to as the Extrapolar Climate Reversal (ECR). This is the most prominent feature in most tropical and subtropical hydroclimate proxies. The initiation of the ECR coincides with the rapid rise in CO2, in part attributed to upwelling in the Southern Ocean and the near collapse of the Atlantic Meridional Overturning Circulation. We attribute the ECR to upwelling of cold deep waters from the Southern Ocean. This is supported by a variety of proxies showing the incursion of deep Southern Ocean waters into the tropics and subtropics. Regional climate variability across the extropolar regions during the interval previously referred to as the “Mystery Interval” can now be explained in the context of the ECR event.
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Affiliation(s)
- Yemane Asmerom
- Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131, USA.
| | - Victor J Polyak
- Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, 87131, USA
| | - Matthew S Lachniet
- Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV, 89154, USA
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10
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Umling NE, Thunell RC. Synchronous deglacial thermocline and deep-water ventilation in the eastern equatorial Pacific. Nat Commun 2017; 8:14203. [PMID: 28112161 PMCID: PMC5264251 DOI: 10.1038/ncomms14203] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 12/07/2016] [Indexed: 11/18/2022] Open
Abstract
The deep ocean is most likely the primary source of the radiocarbon-depleted CO2 released to the atmosphere during the last deglaciation. While there are well-documented millennial scale Δ14C changes during the most recent deglaciation, most marine records lack the resolution needed to identify more rapid ventilation events. Furthermore, potential age model problems with marine Δ14C records may obscure our understanding of the phase relationship between inter-ocean ventilation changes. Here we reconstruct changes in deep water and thermocline radiocarbon content over the last deglaciation in the eastern equatorial Pacific (EEP) using benthic and planktonic foraminiferal 14C. Our records demonstrate that ventilation of EEP thermocline and deep waters occurred synchronously during the last deglaciation. In addition, both gradual and rapid deglacial radiocarbon changes in these Pacific records are coeval with changes in the Atlantic records. This in-phase behaviour suggests that the Southern Ocean overturning was the dominant driver of changes in the Atlantic and Pacific ventilation during deglaciation. Potential age model problems with marine Δ14C records have obscured our understanding of the role of the deep-ocean in deglacial atmospheric CO2 rise. Here, the authors show that deglacial ventilation of EEP thermocline and deep waters occurred synchronously and was coeval with changes in Atlantic records.
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Affiliation(s)
- Natalie E Umling
- School of the Earth, Ocean and Environment, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Robert C Thunell
- School of the Earth, Ocean and Environment, University of South Carolina, Columbia, South Carolina 29208, USA
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11
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Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years. Proc Natl Acad Sci U S A 2016; 113:6119-24. [PMID: 27185933 DOI: 10.1073/pnas.1600616113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.
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12
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Andrews KR, Norton EL, Fernandez-Silva I, Portner E, Goetze E. Multilocus evidence for globally distributed cryptic species and distinct populations across ocean gyres in a mesopelagic copepod. Mol Ecol 2015; 23:5462-79. [PMID: 25283587 DOI: 10.1111/mec.12950] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/17/2014] [Accepted: 09/23/2014] [Indexed: 11/29/2022]
Abstract
Zooplanktonic taxa have a greater number of distinct populations and species than might be predicted based on their large population sizes and open-ocean habitat, which lacks obvious physical barriers to dispersal and gene flow. To gain insight into the evolutionary mechanisms driving genetic diversification in zooplankton, we developed eight microsatellite markers to examine the population structure of an abundant, globally distributed mesopelagic copepod, Haloptilus longicornis, at 18 sample sites across the Atlantic and Pacific Oceans (n = 761). When comparing our microsatellite results with those of a prior study that used a mtDNA marker (mtCOII, n = 1059, 43 sample sites), we unexpectedly found evidence for the presence of a cryptic species pair. These species were globally distributed and apparently sympatric, and were separated by relatively weak genetic divergence (reciprocally monophyletic mtCOII lineages 1.6% divergent; microsatellite FST ranging from 0.28 to 0.88 across loci, P < 0.00001). Using both mtDNA and microsatellite data for the most common of the two species (n = 669 for microsatellites, n = 572 for mtDNA), we also found evidence for allopatric barriers to gene flow within species, with distinct populations separated by continental landmasses and equatorial waters in both the Atlantic and Pacific Ocean basins. Our study shows that oceanic barriers to gene flow can act as a mechanism promoting allopatric diversification in holoplanktonic taxa, despite the high potential dispersal abilities and pelagic habitat for these species.
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Affiliation(s)
- Kimberly R Andrews
- Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA; School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK
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13
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de la Fuente M, Skinner L, Calvo E, Pelejero C, Cacho I. Increased reservoir ages and poorly ventilated deep waters inferred in the glacial Eastern Equatorial Pacific. Nat Commun 2015; 6:7420. [PMID: 26137976 PMCID: PMC4507014 DOI: 10.1038/ncomms8420] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 05/05/2015] [Indexed: 11/09/2022] Open
Abstract
Consistent evidence for a poorly ventilated deep Pacific Ocean that could have released its radiocarbon-depleted carbon stock to the atmosphere during the last deglaciation has long been sought. Such evidence remains lacking, in part due to a paucity of surface reservoir age reconstructions required for accurate deep-ocean ventilation age estimates. Here we combine new radiocarbon data from the Eastern Equatorial Pacific (EEP) with chronostratigraphic calendar age constraints to estimate shallow sub-surface reservoir age variability, and thus provide estimates of deep-ocean ventilation ages. Both shallow- and deep-water ventilation ages drop across the last deglaciation, consistent with similar reconstructions from the South Pacific and Southern Ocean. The observed regional fingerprint linking the Southern Ocean and the EEP is consistent with a dominant southern source for EEP thermocline waters and suggests relatively invariant ocean interior transport pathways but significantly reduced air-sea gas exchange in the glacial southern high latitudes.
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Affiliation(s)
- Maria de la Fuente
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Spain
| | - Luke Skinner
- Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
| | - Eva Calvo
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Spain
| | - Carles Pelejero
- 1] Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Spain [2] Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Isabel Cacho
- Grup de Recerca de Geociències Marines, Departament d'Estratigrafia, Paleontologia i Geociències Marines, Universitat de Barcelona, C/Martí i Franquès, Barcelona 08028, Spain
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14
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Ford HL, Ravelo AC, Polissar PJ. Reduced El Niño-Southern Oscillation during the Last Glacial Maximum. Science 2015; 347:255-8. [PMID: 25593181 DOI: 10.1126/science.1258437] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
El Niño-Southern Oscillation (ENSO) is a major source of global interannual variability, but its response to climate change is uncertain. Paleoclimate records from the Last Glacial Maximum (LGM) provide insight into ENSO behavior when global boundary conditions (ice sheet extent, atmospheric partial pressure of CO2) were different from those today. In this work, we reconstruct LGM temperature variability at equatorial Pacific sites using measurements of individual planktonic foraminifera shells. A deep equatorial thermocline altered the dynamics in the eastern equatorial cold tongue, resulting in reduced ENSO variability during the LGM compared to the Late Holocene. These results suggest that ENSO was not tied directly to the east-west temperature gradient, as previously suggested. Rather, the thermocline of the eastern equatorial Pacific played a decisive role in the ENSO response to LGM climate.
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Affiliation(s)
- Heather L Ford
- Ocean Sciences Department, University of California, Santa Cruz, CA 95064, USA. Biology and Paleo Environment, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA.
| | - A Christina Ravelo
- Ocean Sciences Department, University of California, Santa Cruz, CA 95064, USA
| | - Pratigya J Polissar
- Biology and Paleo Environment, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA
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15
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Palaeoclimate reconstructions reveal a strong link between El Niño-Southern Oscillation and Tropical Pacific mean state. Nat Commun 2014; 4:2692. [PMID: 24176877 DOI: 10.1038/ncomms3692] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 10/01/2013] [Indexed: 11/09/2022] Open
Abstract
The El Niño-Southern Oscillation (ENSO) is one of the most important components of the global climate system, but its potential response to an anthropogenic increase in atmospheric CO2 remains largely unknown. One of the major limitations in ENSO prediction is our poor understanding of the relationship between ENSO variability and long-term changes in Tropical Pacific oceanography. Here we investigate this relationship using palaeorecords derived from the geochemistry of planktonic foraminifera. Our results indicate a strong negative correlation between ENSO variability and zonal gradient of sea-surface temperatures across the Tropical Pacific during the last 22 ky. This strong correlation implies a mechanistic link that tightly couples zonal sea-surface temperature gradient and ENSO variability during large climate changes and provides a unique insight into potential ENSO evolution in the future by suggesting enhanced ENSO variability under a global warming scenario.
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Groom SVC, Stevens MI, Schwarz MP. Parallel responses of bees to Pleistocene climate change in three isolated archipelagos of the southwestern Pacific. Proc Biol Sci 2014; 281:20133293. [PMID: 24807250 DOI: 10.1098/rspb.2013.3293] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The impacts of glacial cycles on the geographical distribution and size of populations have been explored for numerous terrestrial and marine taxa. However, most studies have focused on high latitudes, with only a few focused on the response of biota to the last glacial maximum (LGM) in equatorial regions. Here, we examine how population sizes of key bee fauna in the southwest Pacific archipelagos of Fiji, Vanuatu and Samoa have fluctuated over the Quaternary. We show that all three island faunas suffered massive population declines, roughly corresponding in time to the LGM, followed by rapid expansion post-LGM. Our data therefore suggest that Pleistocene climate change has had major impacts across a very broad tropical region. While other studies indicate widespread Holarctic effects of the LGM, our data suggest a much wider range of latitudes, extending to the tropics, where these climate change repercussions were important. As key pollinators, the inferred changes in these bee faunas may have been critical in the development of the diverse Pacific island flora. The magnitude of these responses indicates future climate change scenarios may have alarming consequences for Pacific island systems involving pollinator-dependent plant communities and agricultural crops.
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Affiliation(s)
- Scott V C Groom
- School of Biological Sciences, Flinders University, , GPO Box 2100, Adelaide, South Australia 5001, Australia, South Australian Museum, , GPO Box 234, Adelaide, South Australia 5000, Australia, School of Pharmacy and Medical Sciences, University of South Australia, , Adelaide, South Australia 5000, Australia
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Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1. Nat Commun 2012; 3:965. [DOI: 10.1038/ncomms1973] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/25/2012] [Indexed: 11/08/2022] Open
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Schmittner A, Urban NM, Shakun JD, Mahowald NM, Clark PU, Bartlein PJ, Mix AC, Rosell-Melé A. Climate sensitivity estimated from temperature reconstructions of the Last Glacial Maximum. Science 2011; 334:1385-8. [PMID: 22116027 DOI: 10.1126/science.1203513] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought.
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Affiliation(s)
- Andreas Schmittner
- College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503, USA.
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Jomelli V, Khodri M, Favier V, Brunstein D, Ledru MP, Wagnon P, Blard PH, Sicart JE, Braucher R, Grancher D, Bourlès DL, Braconnot P, Vuille M. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming. Nature 2011; 474:196-9. [DOI: 10.1038/nature10150] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/21/2011] [Indexed: 11/09/2022]
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Partin JW, Cobb KM, Adkins JF, Clark B, Fernandez DP. Millennial-scale trends in west Pacific warm pool hydrology since the Last Glacial Maximum. Nature 2007; 449:452-5. [PMID: 17898765 DOI: 10.1038/nature06164] [Citation(s) in RCA: 284] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 08/08/2007] [Indexed: 11/09/2022]
Abstract
Models and palaeoclimate data suggest that the tropical Pacific climate system plays a key part in the mechanisms underlying orbital-scale and abrupt climate change. Atmospheric convection over the western tropical Pacific is a major source of heat and moisture to extratropical regions, and may therefore influence the global climate response to a variety of forcing factors. The response of tropical Pacific convection to changes in global climate boundary conditions, abrupt climate changes and radiative forcing remains uncertain, however. Here we present three absolutely dated oxygen isotope records from stalagmites in northern Borneo that reflect changes in west Pacific warm pool hydrology over the past 27,000 years. Our results suggest that convection over the western tropical Pacific weakened 18,000-20,000 years ago, as tropical Pacific and Antarctic temperatures began to rise during the early stages of deglaciation. Convective activity, as inferred from oxygen isotopes, reached a minimum during Heinrich event 1 (ref. 10), when the Atlantic meridional overturning circulation was weak, pointing to feedbacks between the strength of the overturning circulation and tropical Pacific hydrology. There is no evidence of the Younger Dryas event in the stalagmite records, however, suggesting that different mechanisms operated during these two abrupt deglacial climate events. During the Holocene epoch, convective activity appears to track changes in spring and autumn insolation, highlighting the sensitivity of tropical Pacific convection to external radiative forcing. Together, these findings demonstrate that the tropical Pacific hydrological cycle is sensitive to high-latitude climate processes in both hemispheres, as well as to external radiative forcing, and that it may have a central role in abrupt climate change events.
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Affiliation(s)
- Judson W Partin
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
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Kienast M, Kienast SS, Calvert SE, Eglinton TI, Mollenhauer G, François R, Mix AC. Erratum: Eastern Pacific cooling and Atlantic overturning circulation during the last deglaciation. Nature 2006. [DOI: 10.1038/nature05377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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