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| Registros recuperados: 26 | |
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| Stuut, Jan‐berend W.; De Deckker, Patrick; Saavedra‐pellitero, Mariem; Bassinot, Franck; Drury, Anna‐joy; Walczak, Maureen H.; Nagashima, Kana; Murayama, Masafumi. |
| New proxy records from deep‐sea sediment cores from the northwestern continental margin of Western Australian reveal a 5.3 million‐year (Ma) history of aridity and tropical‐monsoon activity in northwestern Australia. Following the warm and dry early Pliocene (~5.3 Ma), the northwestern Australian continent experienced a gradual increase in humidity peaking at about 3.8 Ma with higher than present‐day rainfall. Between 3.8 and about 2.8 Ma, climate became progressively more arid with more rainfall variability. Coinciding with the onset of the northern hemisphere glaciations and the intensification of the northern hemisphere monsoon, aridity continued to increase overall from 2.8 Ma until today, with greater variance in precipitation and an increased... |
| Tipo: Text |
Palavras-chave: Paleoclimate; Monsoon; Australia; Runoff; Pliocene; Quaternary. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00502/61384/65035.pdf |
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| Dolven, Jk; Cortese, G; Bjorklund, Kr. |
| Polycystine radiolarians are used to reconstruct summer sea surface temperatures (SSSTs) for the Late Pleistocene-Holocene (600-13,400 C-14 years BP) in the Norwegian Sea. At 13,200 C-14 years BP, the SSST was close to the average Holocene SSST (similar to12degreesC). It then gradually dropped to 7.1degreesC in the Younger Dryas. Near the Younger Dryas-Holocene transition (similar to10,000 C-14 years BP), the SSST increased 5degreesC in about 530 years. Four abrupt cooling events, with temperature drops of up to 2.1degreesC, are recognized during the Holocene: at 9340, 7100 ("8200 calendar years event''), 6400 and 1650 C-14 years BP. Radiolarian SSSTs and the isotopic signal from the GISP2 ice core are strongly coupled, stressing the importance of the... |
| Tipo: Text |
Palavras-chave: Radiolarians; Paleoclimate; Late Pleistocene-Holocene; Norwegian Sea. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33384/31894.pdf |
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| Amore, F. O.; Flores, J. A.; Voelker, A. H. L.; Lebreiro, S. M.; Palumbo, E.; Sierro, F. J.. |
| Changes in paleoclimate and paleoproductivity patterns have been identified by analysing, in conjunction with other available proxy data, the coccolithophore assemblages from core MD03-2699, located in the Portuguese margin in the time interval from the Marine Isotope Stage (MIS) 13/14 boundary to MIS 9 (535 to 300 ka). During the Mid-Brunhes event, the assemblages associated with the eccentricity minima are characterised by higher nannoplankton accumulation rate (NAR) values and by the blooming of the opportunistic genus Gephyrocapsa. Changes in coccolithophore abundance are also related to glacial-interglacial cycles. Higher NAR and numbers of coccoliths/g mainly occurred during the interglacial periods, while these values decreased during the glacial... |
| Tipo: Text |
Palavras-chave: North Atlantic Ocean; Mid-Pleistocene; Coccolithophores; Paleoclimate; Paleoproductivity. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00092/20286/17946.pdf |
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| Railsback, L. Bruce; Brook, George A.; Liang, Fuyuan; Marais, Eugene; Cheng, Hai; Edwards, R. Lawrence. |
| Stalagmite Orum-1 from a cave near Orumana in northwestern Namibia provides a multi-proxy record of regional drying with increasing global-scale warmth over the last 47 kyr, in a region with few long well-dated location specific paleoclimate records. Data from Stalagmite Orum-1 include carbon and oxygen stable isotope ratios, proportions of aragonite and calcite, pronouncedly differing petrographic fabrics, positions of layer-bounding surfaces, variation in layer-specific width, and changes in layer thickness, all of which combine to support change from wetter to drier conditions. Combined with fourteen U-Th ages, they suggest that climate was wetter in northwestern Namibia during globally cold MIS 3 than it is today, and with more grass than is present... |
| Tipo: Text |
Palavras-chave: Namibia; Paleoclimate; Pleistocene; Holocene; Savanna; Stalagmite. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53213/54862.pdf |
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| Mairesse, Aurélien. |
| The study of past climates and of mechanisms that have influenced their evolution is the key to anticipate the future climate changes. This doctoral thesis focusses on the Holocene climate, the ongoing interglacial, that starts about 11,700 years ago. The current paleoclimate knowledge is based on the one hand, on the climate models results and, on the other hand, on the reconstruction of physical variables derived from climate archives as the ice cores, the marine cores or the pollens for instance. These two types of information are complementary. Here we have combined them to obtain reconstructions of past climates using data assimilation. This technique is standard in many disciplines but not yet in paleoclimatology. The data assimilation method applied... |
| Tipo: Text |
Palavras-chave: Climate; Data assimilation; Paleoclimate; Holocene; LOVECLIM model; Proxy record. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00506/61719/65687.pdf |
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| Shakun, Jeremy D. |
| This dissertation presents the results of statistical analyses of large climate datasets from two time intervals – the 20th century instrumental record and the proxy record of the last deglaciation – in order to understand the forcings and mechanisms of past climate variability. A longstanding question in climate dynamics concerns the origin of Pacific decadal variability (PDV). This issue is addressed by calculating the Southern Hemisphere equivalent of the Pacific Decadal Oscillation (PDO) index from Pacific sea surface temperature (SST) anomalies over the 20th century, which is found to be similar to its Northern Hemisphere counterpart. The Northern and Southern PDO indices both exhibit pronounced seasonality in autocorrelation with interannual... |
| Tipo: Text |
Palavras-chave: El Nino-Southern Oscillation; Pacific Decadal Oscillation; Paleoclimate; Deglaciation; Ocean circulation; Milankovitch; Greenhouse gases. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00495/60654/64151.pdf |
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| Thomas, Elizabeh R; Allen, Claire S; Etourneau, Johan; King, Amy Cf; Severi, Mirko; Winton, V. Holly L.; Mueller, Juliane; Crosta, Xavier; Peck, Victoria L.. |
| Dramatic changes in sea ice have been observed in both poles in recent decades. However, the observational period for sea ice is short, and the climate models tasked with predicting future change in sea ice struggle to capture the current Antarctic trends. Paleoclimate archives, from marine sedimentary records and coastal Antarctic ice cores, provide a means of understanding sea ice variability and its drivers over decadal to centennial timescales. In this study, we collate published records of Antarctic sea ice over the past 2000 years (2 ka). We evaluate the current proxies and explore the potential of combining marine and ice core records to produce multi-archive reconstructions. Despite identifying 92 sea ice reconstructions, the spatial and temporal... |
| Tipo: Text |
Palavras-chave: Sea ice; Antarctica; Paleoclimate; Ice cores; Marine sediments. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00595/70709/68916.pdf |
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| Soulet, Guillaume; Menot, Guillemette; Garreta, Vincent; Rostek, Frauke; Zaragosi, Sebastien; Lericolais, Gilles; Bard, Edouard. |
| Chronologies of sediments that document the last glacial history of the Black Sea "Lake" are hampered by issues relating to reservoir age. Regulated by basin hydrology, reservoir ages represent a tool that could potentially be used to better understand the response of Black Sea "Lake" hydrology to climate change. Therefore, deciphering reservoir age evolution is crucial both for better constraining the basin chronological framework and for providing new insights into our understanding of Black Sea "Lake" hydrology. By tuning a meaningful new high-resolution geochemical dataset (obtained from core MD04-2790) to a climate reference record, here, we propose a reliable chronology spanning the last 32 kyr BP. The chronology is compared to a large AMS... |
| Tipo: Text |
Palavras-chave: Black Sea; Reservoir age; Radiocarbon; Last Glacial; Last Deglaciation; Paleoclimate. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00043/15379/12817.pdf |
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| Rasmussen, Tine L.; Thomsen, Erik. |
| The last deglaciation, 20,000–10,000 years ago, was a period of global warming and rapidly shrinking ice sheets. It was also climatically unstable and retreats were interrupted by re-advances. Retreat rates and timing relative to climatic changes have therefore been difficult to establish. We here study a suite of 12 marine sediment cores from Storfjorden and Storfjorden Trough, Svalbard. The purpose is to reconstruct retreat patterns and retreat rates of a high northern latitude marine-based ice stream from the Svalbard-Barents Sea Ice Sheet in relation to paleoceanographic and paleoclimatic changes. The study is based on abundance and composition of planktic and benthic foraminiferal assemblages, ice rafted debris (IRD), lithology, and 70 AMS-14C dates.... |
| Tipo: Text |
Palavras-chave: Ice retreat rates; Storfjorden ice stream; Paleoceanography; Paleoclimate; Paleotemperature. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00658/77019/78289.pdf |
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| Hill, T. M.; Kennett, J. P.; Valentine, D. L.; Yang, Z.; Reddy, C. M.; Nelson, R. K.; Behl, R. J.; Robert, C.; Beaufort, L.. |
| Marine hydrocarbon seepage emits oil and gas, including methane (approximate to 30 Tg of CH4 per year), to the ocean and atmosphere. Sediments from the California margin contain preserved tar, primarily formed through hydrocarbon weathering at the sea surface. We present a record of variation in the abundance of tar in sediments for the past 32,000 years, providing evidence for increases in hydrocarbon emissions before and during Termination IA [16,000 years ago (16 ka) to 14 ka] and again over Termination IB (11-10 ka). Our study provides direct evidence for increased hydrocarbon seepage associated with deglacial warming through tar abundance in marine sediments, independent of previous geochemical proxies. Climate-sensitive gas hydrates may modulate... |
| Tipo: Text |
Palavras-chave: Methane; Paleoclimate; Quaternary climate; Hydrate; Tar. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34524/33432.pdf |
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| Leal,Alejandra; Perez,Tibisay; Bilbao,Bibiana. |
| A palynological analysis of an organic paleosol found at 150-125 cm depth in a Mauritia swamp from the Eastern Orinoco Llanos is presented. The 25 cm pollen record summarizes the vegetation history during the Early Holocene, from 10,225 to 7,800 calendar yr BP. The vegetation was characterized by a Poaceae marsh, where Asteraceae, Melastomataceae, Schefflera-type and Phyllanthus were the most abundant shrubs and trees. Pollen-types richness was lower than that recorded today in similar environments, and Mauritia pollen was absent. Results suggest that climate was as humid as present during the beginning of the Holocene, with a decreasing trend in humidity from around 8,000-7,000 yr BP, in coincidence with the beginning of the "Early-Mid-Holocene Dryness"... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Orinoco Llanos; Mauritia swamp; Early Holocene; Paleoclimate; Early-Mid Holocene Dryness. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672011000400009 |
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| Rustic, Gerald Thomas. |
| The El Niño Southern Oscillation (ENSO) has been implicated in large-scale climate shifts of the past millennia, but paleoclimate records from the dynamically vital eastern equatorial Pacific Ocean (EEP) spanning the past millennium are sparse. This has limited our understanding of tropical Pacific dynamics, leaving questions regarding the source of ENSO variability unanswered. Here I seek to address some of these questions regarding relationship between ENSO and tropical Pacific mean state, and the relationship between the tropical Pacific and large-scale climate. Mean EEP sea surface temperature (SST) for the past millennium was reconstructed using Mg/Ca ratios in Globigerinoides ruber from a sub-centennially resolved sediment core collected near the... |
| Tipo: Text |
Palavras-chave: Eastern tropical pacific; ENSO; Foraminifera; Paleoceanography; Paleoclimate. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00495/60657/64154.pdf |
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| Essallami, L.; Sicre, M. A.; Kallel, N.; Labeyrie, L.; Siani, G.. |
| Sea surface temperatures were reconstructed over the last 30,000 years from alkenone paleothermometry (SST-(alk)) and planktonic foraminifera assemblages using the Modern Analog Technique (MAT) (SST-(foram)) along two cores of the Mediterranean Sea: MD84-632 (Levantine basin) and MD04-2797 (Siculo-Tunisian Strait). Oxygen isotope of planktonic foraminifera G. bulloides for core MD04-2797 and G. ruber for core MD84-632 were also determined. SST-alk in the Levantine basin indicate colder values at the Last Glacial Maximum (LGM) (similar to 14 degrees C) than earlier established from MAT, and a cooling amplitude of 6 degrees-7 degrees C, comparable to the central Mediterranean Sea. Climatic events such as the Younger Dryas (YD) and Heinrich events 1 and 2 (H1... |
| Tipo: Text |
Palavras-chave: Paleoclimate; Glacial; Mediterranean; Alkenones; Foraminifera; Marine core. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00208/31954/30378.pdf |
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| Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.; Haggart, James W.; Popov, Evgeny; Guzhov, Alexander; Rogov, Mikhail; Delsate, Dominique; Thies, Detlev; Cuny, Gilles; Puceat, Emmanuelle; Charbonnier, Guillaume; Bayon, Germain. |
| The breakup of Pangea and onset of growth of the Pacific plate led to several paleoenvironmental feedbacks, which radically affected paleoclimate and ocean chemistry during the Jurassic. Overall, this period was characterized by intense volcanic degassing from large igneous provinces and circum-Panthalassan arcs, new oceanic circulation patterns, and changes in heat and humidity transports affecting continental weathering. Few studies, however, have attempted to unravel the global interactions linking these processes over the long-term. In this paper, we address this question by documenting the global changes in continental drainage and surface oceanic circulation for the whole Jurassic period. For this purpose, we present 53 new neodymium isotope values... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Jurassic; Paleoclimate; Paleoceanography; Continental drainage. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00179/29015/27443.pdf |
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| Hoffman, Jeremy Scott. |
| This dissertation explores one overarching question relevant to the paleoclimate of the latest Pleistocene glacial cycle (approximately the last 130,000 years): “How did spatial and temporal evolution of ocean temperature, both at the surface and interior, relate to other parts of the climate system in the late Pleistocene?” Results from three studies are presented that seek to address longstanding questions in paleoceanography and paleoclimatology for the late Pleistocene using a combination of novel and accepted statistical and geochemical analysis techniques and leveraging comparisons with available global climate model data. The last interglaciation (LIG; ~129-116 ka) was the most recent period in Earth’s history with higher-than-present global sea... |
| Tipo: Text |
Palavras-chave: Paleoclimate; Interglacial; Heinrich events; Deglacial; Paleoceanography; Climate. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00505/61702/65670.pdf |
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| Rabineau, Marina; Cloetingh, S.; Kuroda, J.; Aslanian, Daniel; Droxler, A.; Gorini, C.; Garcia-castellanos, D.; Moscariello, A.; Burov, E.; Sierro, F.; Lirer, F.; Roure, F.; Pezard, P. A.; Matenco, L.; Hello, Y.; Mart, Y.; Camerlenghi, A.; Tripati, A.. |
| During the last decade, the interaction of deep processes in the lithosphere and mantle with surface processes (erosion, climate, sea-level, subsidence, glacio-isostatic readjustment) has been the subject of heated discussion. The use of a multidisciplinary approach linking geology, geophysics, geodesy, modelling, and geotechnology has led to the awareness of coupled deep and surface processes. Deep earth dynamics (topography, erosion, tectonics) are strongly connected to natural hazards such as earthquakes, landslides, and tsunamis; sedimentary mass transfers have important consequences on isostatic movements and on georesources, geothermal energy repartitions. The ability to read and understand the link between deep Earth dynamics and surface processes... |
| Tipo: Text |
Palavras-chave: Deep drilling; Geodynamics; Passive margins; Paleoclimate; Messinian erosional and salinity crisis; Deep biosphere; Georesources. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00256/36741/35342.pdf |
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| Registros recuperados: 26 | |
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