Search

Your search keyword '"M.-P. Ledru"' showing total 19 results
Start Over Author "M.-P. Ledru"
19 results on '"M.-P. Ledru"'

1. The ACER pollen and charcoal database: a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

Author

M. F. Sánchez Goñi, S. Desprat, A.-L. Daniau, F. C. Bassinot, J. M. Polanco-Martínez, S. P. Harrison, J. R. M. Allen, R. S. Anderson, H. Behling, R. Bonnefille, F. Burjachs, J. S. Carrión, R. Cheddadi, J. S. Clark, N. Combourieu-Nebout, Colin. J. Courtney Mustaphi, G. H. Debusk, L. M. Dupont, J. M. Finch, W. J. Fletcher, M. Giardini, C. González, W. D. Gosling, L. D. Grigg, E. C. Grimm, R. Hayashi, K. Helmens, L. E. Heusser, T. Hill, G. Hope, B. Huntley, Y. Igarashi, T. Irino, B. Jacobs, G. Jiménez-Moreno, S. Kawai, A. P. Kershaw, F. Kumon, I. T. Lawson, M.-P. Ledru, A.-M. Lézine, P. M. Liew, D. Magri, R. Marchant, V. Margari, F. E. Mayle, G. M. McKenzie, P. Moss, S. Müller, U. C. Müller, F. Naughton, R. M. Newnham, T. Oba, R. Pérez-Obiol, R. Pini, C. Ravazzi, K. H. Roucoux, S. M. Rucina, L. Scott, H. Takahara, P. C. Tzedakis, D. H. Urrego, B. van Geel, B. G. Valencia, M. J. Vandergoes, A. Vincens, C. L. Whitlock, D. A. Willard, and M. Yamamoto

Subjects
Environmental sciences, GE1-350, Geology, QE1-996.5
Abstract

Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard–Oeschger (D–O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D–O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73–15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U∕230Th, optically stimulated luminescence (OSL), 40Ar∕39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft AccessTM at https://doi.org/10.1594/PANGAEA.870867.

Published
2017
Full Text
View/download PDF

2. Terrestrial biosphere changes over the last 120 kyr

Author

B. A. A. Hoogakker, R. S. Smith, J. S. Singarayer, R. Marchant, I. C. Prentice, J. R. M. Allen, R. S. Anderson, S. A. Bhagwat, H. Behling, O. Borisova, M. Bush, A. Correa-Metrio, A. de Vernal, J. M. Finch, B. Fréchette, S. Lozano-Garcia, W. D. Gosling, W. Granoszewski, E. C. Grimm, E. Grüger, J. Hanselman, S. P. Harrison, T. R. Hill, B. Huntley, G. Jiménez-Moreno, P. Kershaw, M.-P. Ledru, D. Magri, M. McKenzie, U. Müller, T. Nakagawa, E. Novenko, D. Penny, L. Sadori, L. Scott, J. Stevenson, P. J. Valdes, M. Vandergoes, A. Velichko, C. Whitlock, and C. Tzedakis

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C.

Published
2016
Full Text
View/download PDF

3. Why deep drilling in the Colônia Basin (Brazil)?

Author

M.-P. Ledru, W. U. Reimold, D. Ariztegui, E. Bard, A. P. Crósta, C. Riccomini, and A. O. Sawakuchi

Subjects
Geology, QE1-996.5
Abstract

The Colônia Deep Drilling Project held its first International Continental Scientific Drilling Program (ICDP) workshop in September 2014 at the University of São Paulo (Brazil). Twenty-seven experts from six countries discussed the feasibility and the expectations of a deep drilling in the structure of Colônia located at the southwestern margin of the city of São Paulo. After presenting the studies performed at the site during the last decades, participants focused on the objectives, priorities and detailed planning for a full deep-drilling proposal. An excursion to the site and new auger coring showed the importance of the Colônia site for studying the evolution of a tropical rainforest and to evaluate the interplay between the South American summer monsoon, the Intertropical Convergence Zone (ITCZ) and the southern Westerlies belt during the last 5 million years. In addition, deep drilling will eventually solve the still unresolved issue of the origin of the structure of Colônia as a result of meteorite impact or endogenous processes.

Published
2015
Full Text
View/download PDF

4. A mid-Holocene climate reconstruction for eastern South America

Author

L. F. Prado, I. Wainer, C. M. Chiessi, M.-P. Ledru, and B. Turcq

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

The mid-Holocene (6000 calibrated years before present) is a key period in palaeoclimatology because incoming summer insolation was lower than during the late Holocene in the Southern Hemisphere, whereas the opposite happened in the Northern Hemisphere. However, the effects of the decreased austral summer insolation over South American climate have been poorly discussed by palaeodata syntheses. In addition, only a few of the regional studies have characterised the mid-Holocene climate in South America through a multiproxy approach. Here, we present a multiproxy compilation of mid-Holocene palaeoclimate data for eastern South America. We compiled 120 palaeoclimatological datasets, which were published in 84 different papers. The palaeodata analysed here suggest a water deficit scenario in the majority of eastern South America during the mid-Holocene if compared to the late Holocene, with the exception of northeastern Brazil. Low mid-Holocene austral summer insolation caused a reduced land–sea temperature contrast and hence a weakened South American monsoon system circulation. This scenario is represented by a decrease in precipitation over the South Atlantic Convergence Zone area, saltier conditions along the South American continental margin, and lower lake levels.

Published
2013
Full Text
View/download PDF

5. The Medieval Climate Anomaly and the Little Ice Age in the eastern Ecuadorian Andes

Author

M.-P. Ledru, V. Jomelli, P. Samaniego, M. Vuille, S. Hidalgo, M. Herrera, and C. Ceron

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

To better characterize the climate variability of the last millennium in the high Andes, we analyzed the pollen content of a 1150-yr-old sediment core collected in a bog located at 3800 m a.s.l. in the páramo in the eastern Cordillera in Ecuador. An upslope convective index based on the ratio between cloud transported pollen from the Andean forest to the bog (T) and Poaceae pollen frequencies, related to the edaphic moisture of the páramo (P), was defined. This index was used to distinguish changes in the atmospheric moisture from the soil moisture content of the páramo and their associated patterns of interdecadal El Niño–Southern Oscillation (ENSO) variability and South American summer monsoon (SASM) activity. Results show that between 850 and 1250 AD, the Medieval Climate Anomaly interval was warm and moist with a high transported pollen/Poaceae pollen (T/P) index linked to high ENSO variability and weak SASM activity. Between 1250 and 1550 AD, a dry climate prevailed, characterized by an abrupt decrease in the T/P index and therefore no upslope cloud convection, related to lower ENSO variability and with significant impact on the floristic composition of the páramo. During the Little Ice Age, two phases were observed: first, a wet phase between 1550 and 1750 AD linked to low ENSO variability in the Pacific and warm south equatorial Atlantic sea surface temperatures (SSTs) favored the return of a wet páramo, and then a cold and dry phase between 1750 and 1800 AD associated with low ENSO variability and weak SASM activity resulted in drying of the páramo. The current warm period marks the beginning of a climate characterized by high convective activity – the highest in the last millennium – and weaker SASM activity modifying the water storage of the páramo. Our results show that the páramo is progressively losing its capacity for water storage and that the interdecadal variability of both tropical Pacific and Atlantic SSTs matter for Andean climate patterns, although many teleconnection mechanisms are still poorly understood.

Published
2013
Full Text
View/download PDF

6. Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years ago

Author

R. Marchant, A. Cleef, S. P. Harrison, H. Hooghiemstra, V. Markgraf, J. van Boxel, T. Ager, L. Almeida, R. Anderson, C. Baied, H. Behling, J. C. Berrio, R. Burbridge, S. Björck, R. Byrne, M. Bush, J. Duivenvoorden, J. Flenley, P. De Oliveira, B. van Geel, K. Graf, W. D. Gosling, S. Harbele, T. van der Hammen, B. Hansen, S. Horn, P. Kuhry, M.-P. Ledru, F. Mayle, B. Leyden, S. Lozano-García, A. M. Melief, P. Moreno, N. T. Moar, A. Prieto, G. van Reenen, M. Salgado-Labouriau, F. Schäbitz, E. J. Schreve-Brinkman, and M. Wille

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small; change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America show a change in biome assignment, but to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucatán peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation reflecting a generally cool and dry environment. Cool grass/shrubland is prevalent in southeast Brazil whereas Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain forest indicating that forest was present at some locations at the LGM. Some sites in Central Mexico and lowland Colombia remain unchanged in the biome assignments of warm mixed forest and tropical dry forest respectively, although the affinities that these sites have to different biomes do change between 18 000±1000 14C yr BP and present. The "unresponsive" nature of these sites results from their location and the impact of local edaphic influence.

Published
2009

7. Environmental records from temperate glacier ice on Nevado Coropuna saddle, southern Peru

Author

J. Herreros, I. Moreno, J.-D. Taupin, P. Ginot, N. Patris, M. De Angelis, M.-P. Ledru, F. Delachaux, and U. Schotterer

Subjects
Science, Geology, QE1-996.5, Dynamic and structural geology, QE500-639.5
Abstract

We investigated past climate variability and the zonal short and long-range transport of air masses in tropical South America using chemical, isotopic and palynological signals from a 42 m-long ice core recovered in 2003 from the saddle of the Nevado Coropuna, southern Peru (72°39´ W; 15°32´ S; 6080 m a.s.l.). We found that precipitation at this site depends mainly on the easterly circulation of air masses originated from the tropical Atlantic Ocean. Nevertheless, sporadic Pacific air masses arrivals, and strong cold waves coming from southern South America reach this altitude site. In spite of post-depositional effects, we were able to identify two strong ENSO (El Niño-Southern Oscillation) event signatures (1982–1983 and 1992) and the eruptive activity of the nearby Sabancaya volcano (1994).

Published
2009
Full Text
View/download PDF

8. Terrestrial biosphere changes over the last 120 kyr

Author

Mark B. Bush, Jemma M. Finch, Laura Sadori, Trevor Hill, Shonil A. Bhagwat, Ulrich C Müller, Sandy P. Harrison, Takeshi Nakagawa, Babette A A Hoogakker, A. de Vernal, Judy R M Allen, Merna McKenzie, Gonzalo Jiménez-Moreno, Dan Penny, C. Tzedakis, Hermann Behling, Bianca Fréchette, Olga K. Borisova, M. Vandergoes, Brian Huntley, Alexander Correa-Metrio, Iain Colin Prentice, Peter Kershaw, Jennifer A. Hanselman, Wojciech Granoszewski, Eberhard Grüger, Joy S. Singarayer, Eric C. Grimm, Paul J. Valdes, Rob Marchant, Louis Scott, R. S. Anderson, Donatella Magri, A.A. Velichko, Janelle Stevenson, Cathy Whitlock, M.-P. Ledru, Elena Novenko, Robin S. Smith, William D. Gosling, Socorro Lozano-García, Fischer, H., Paleoecology and Landscape Ecology (IBED, FNWI), Department of Earth Sciences [Oxford], University of Oxford [Oxford], University of Reading (UOR), Bristol Research Initiative for the Dynamic Global Environment (BRIDGE), School of Geographical Sciences [Bristol], University of Bristol [Bristol]-University of Bristol [Bristol], University of York [York, UK], Grantham Institute for Climate Change and the Environment, Imperial College London, Department of Life Sciences, Department of Biological Sciences [North Ryde], Macquarie University, Durham University, Northern Arizona University [Flagstaff], The Open University [Milton Keynes] (OU), Georg-August-University [Göttingen], Institute of Geography of RAS, Russian Academy of Sciences [Moscow] (RAS), Florida Institute of Technology [Melbourne], Universidad Nacional Autónoma de México (UNAM), Centre de recherche sur la dynamique du système Terre (GEOTOP), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), University of KwaZulu-Natal (UKZN), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam [Amsterdam] (UvA), Polish Geological Institute, National Research Institute, Illinois State Museum, Centre for Past Climate Change (CPCC), School of Archaeology, Geography and Environmental Sciences (SAGES), Universidad de Granada (UGR), Monash University [Melbourne], Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Monash University [Clayton], Biodiversity and Climate Research Centre (BiK-F) (LOEWE), Institute of Geosciences [Frankfurt am Main], Goethe-Universität Frankfurt am Main, Ritsumeikan University, EarthByte Group, School of Geosciences, The University of Sydney, University of the Free State [South Africa], Australian National University (ANU), Climate Change Institute [Orono] (CCI), University of Maine, Department of Earth Sciences [MSU Bozeman], Montana State University (MSU), Department of Geography, University College of London [London] (UCL), University of Oxford, Georg-August-University = Georg-August-Universität Göttingen, Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), École Polytechnique de Montréal (EPM)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal = University of Québec in Montréal (UQAM), University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), Universidad de Granada = University of Granada (UGR), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), and University of the Free State [South Africa] (UFS)

Subjects
010506 paleontology, Terrestrial biosphere changes, 010504 meteorology & atmospheric sciences, lcsh:Environmental protection, POLLEN-BASED RECONSTRUCTIONS, Biome, global and planetary change, C-14 YR BP, 01 natural sciences, lcsh:Environmental pollution, PRETORIA SALTPAN, ddc:550, Meteorology & Atmospheric Sciences, ATMOSPHERIC CARBON-DIOXIDE, lcsh:TD169-171.8, GLACIAL-MAXIMUM, Geosciences, Multidisciplinary, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, Carbon dioxide in Earth's atmosphere, Science & Technology, LATE-PLEISTOCENE, Biosphere, Temperate forest, Primary production, stratigraphy, Last Glacial Maximum, Geology, 15. Life on land, Tundra, MILLENNIAL-SCALE VARIABILITY, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, lcsh:TD172-193.5, Physical Sciences, Terrestrial ecosystem, Physical geography, [SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology, VEGETATION RECORDS, paleontology, PLANT MACROFOSSIL DATA, RAPID CLIMATE-CHANGE, 0406 Physical Geography And Environmental Geoscience
Abstract

A new global synthesis and biomization of long (> 40 kyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacial–interglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74 ka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C.

Published
2016
Full Text
View/download PDF

9. Climate variability and human impact in South America during the last 2000 years: synthesis and perspectives from pollen records

Author

Hermann Behling, M. S. Tonello, Francis E. Mayle, Antonio Maldonado, Valentí Rull, Bronwen S. Whitney, M.-P. Ledru, Mathias Vuille, John Carson, William D. Gosling, Henry Hooghiemstra, Encarni Montoya, Isabel Hoyos, Catalina González-Arango, S.G.A. Flantua, Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam [Amsterdam] (UvA), Department of Atmospheric and Environmental Sciences [Albany] (DAES), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), Georg-August-University = Georg-August-Universität Göttingen, University of Reading (UOR), Department of Environment, Earth and Ecosystems [Open University], The Open University [Milton Keynes] (OU), Universidad de Antioquia = University of Antioquia [Medellín, Colombia], Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Centro de Estudios Avanzados en Zonas Aridas (CEAZA), Universidad de La Serena (USERENA), Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Instituto de Investigaciones Marinas y Costeras [Mar del Plata] (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Mar del Plata], Universidad Nacional de Mar del Plata [Mar del Plata] (UNMdP)-Universidad Nacional de Mar del Plata [Mar del Plata] (UNMdP), University of Northumbria at Newcastle [United Kingdom], Departamento de Ciencias Biológicas [Univ de los Andes Colombia] (UNIANDES), Universidad de los Andes [Bogota] (UNIANDES), Netherlands Organization for Scientific Research, Georg-August-University [Göttingen], École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Facultad de Ciencias Exactas y Naturales [Mar del Plata], Universidad Nacional de Mar del Plata [Mar del Plata] (UNMdP)-Universidad Nacional de Mar del Plata [Mar del Plata] (UNMdP)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), and Paleoecology and Landscape Ecology (IBED, FNWI)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Environmental change, Stratigraphy, lcsh:Environmental protection, Climate variability, South America, pollen records, Climate change, F800, medicine.disease_cause, 01 natural sciences, lcsh:Environmental pollution, Pollen, medicine, lcsh:TD169-171.8, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Palynology, lcsh:GE1-350, Global and Planetary Change, Paleontology, Plant community, Vegetation, 15. Life on land, Geography, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, lcsh:TD172-193.5, Spatial variability, Climate model, [SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology
Abstract

An improved understanding of present-day climate variability and change relies on high-quality data sets from the past 2 millennia. Global efforts to model regional climate modes are in the process of being validated against, and integrated with, records of past vegetation change. For South America, however, the full potential of vegetation records for evaluating and improving climate models has hitherto not been sufficiently acknowledged due to an absence of information on the spatial and temporal coverage of study sites. This paper therefore serves as a guide to high-quality pollen records that capture environmental variability during the last 2 millennia. We identify 60 vegetation (pollen) records from across South America which satisfy geochronological requirements set out for climate modelling, and we discuss their sensitivity to the spatial signature of climate modes throughout the continent. Diverse patterns of vegetation response to climate change are observed, with more similar patterns of change in the lowlands and varying intensity and direction of responses in the highlands. Pollen records display local-scale responses to climate modes; thus, it is necessary to understand how vegetation-climate interactions might diverge under variable settings. We provide a qualitative translation from pollen metrics to climate variables. Additionally, pollen is an excellent indicator of human impact through time. We discuss evidence for human land use in pollen records and provide an overview considered useful for archaeological hypothesis testing and important in distinguishing natural from anthropogenically driven vegetation change. We stress the need for the palynological community to be more familiar with climate variability patterns to correctly attribute the potential causes of observed vegetation dynamics. This manuscript forms part of the wider LOng-Term multi-proxy climate REconstructions and Dynamics in South America - 2k initiative that provides the ideal framework for the integration of the various palaeoclimatic subdisciplines and palaeo-science, thereby jump-starting and fostering multidisciplinary research into environmental change on centennial and millennial timescales., We thank the Netherlands Organization for Scientific Research (NWO, grant 2012/13248/ALW) for financial support for the project of Suzette Flantua. We are grateful for the support provided to Mathias Vuille by NSF-P2C2 (AGS-1303828) and to Encarni Montoya by the NERC fellowship (NE/J018562/1). Isabel Hoyos is supported by the USAID-NSF PEER program, project 31, and CODI Universidad de Antioquia.

Published
2016
Full Text
View/download PDF

10. Supplementary material to 'Terrestrial biosphere changes over the last 120 kyr and their impact on ocean δ 13C'

Author

B. A. A. Hoogakker, R. S. Smith, J. S. Singarayer, R. Marchant, I. C. Prentice, J. R. M. Allen, R. S. Anderson, S. A. Bhagwat, H. Behling, O. Borisova, M. Bush, A. Correa-Metrio, A. de Vernal, J. M. Finch, B. Fréchette, S. Lozano-Garcia, W. D. Gosling, W. Granoszewski, E. C. Grimm, E. Grüger, J. Hanselman, S. P. Harrison, T. R. Hill, B. Huntley, G. Jiménez-Moreno, P. Kershaw, M.-P. Ledru, D. Magri, M. McKenzie, U. Müller, T. Nakagawa, E. Novenko, D. Penny, L. Sadori, L. Scott, J. Stevenson, P. J. Valdes, M. Vandergoes, A. Velichko, C. Whitlock, and C. Tzedakis

Published
2015
Full Text
View/download PDF

11. Paleo-environmental change in Amazonian and African rainforest during the LGM

Author

Renato Campello Cordeiro, Ana Luiza Spadano Albuquerque, A. Siffedine, Dieter Anhuf, Luiz Carlos Ruiz Pessenda, M. P. Ledru, T. van der Hammen, Ivo Karmann, P.E. De Oliveira, José A. Marengo, P. L. da Silva Dias, F.W. Da Cruz, and Hermann Behling

Subjects
Environmental change, Amazon rainforest, Amazonian, Paleontology, Tropics, Last Glacial Maximum, Rainforest, Oceanography, Climatology, Glacial period, Precipitation, Ecology, Evolution, Behavior and Systematics, Geology, Earth-Surface Processes
Abstract

The paper provides new and comparative insight into the ecological history of the two largest continental tropical forest areas during the Last Glacial Maximum (LGM). The tropical forest regions are of particular interest because they present a large source of heat and have been shown to have significant impact on the extra tropical atmospheric circulation. They are also the most intense land-based convective centers. Thus, especially from the tropics paleoecological information is needed as benchmarks for climate modeling. The African data for LGM climates were published earlier including the reconstructed paleoprecipitation patterns deduced from SSTs. The tropical South American LGM data were interpreted from pollen, geochemical, and δ18O (stable oxygen isotope) data from Brazil and selected surrounding areas. The available terrestrial data are consistent with the SST derived precipitation data for the tropical forests in Brazil and for Africa. However, the impact of LGM climate extremes was less severe in the Amazon than in the Congo basin. The LGM humid forest area (including evergreen and semi-deciduous forest types) in Africa was probably reduced by 84%. In contrast, the Amazon humid forest area probably shrank to 54% of their present-day extension. Still, there are different interpretations with respect to the amount of reduction of the Amazon forest area during the LGM. Although direct information about LGM climates in Amazonia is still limited the more detailed map obtained in the present work, however, allows a more reliable characterization of the last glacial tropical environment than previously published for the Amazon region.

Published
2006
Full Text
View/download PDF

12. The Medieval Climate Anomaly and the Little Ice Age in the eastern Ecuadorian Andes

Author

Silvana Hidalgo, M. Herrera, C. Ceron, Mathias Vuille, Pablo Samaniego, M.-P. Ledru, Vincent Jomelli, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric and Environmental Sciences [Albany] (DAES), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), instituto Geofísico, Escuela Politécnica Nacional (EPN), Universidad Centrale del Ecuador, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, lcsh:Environmental protection, Stratigraphy, [SDE.MCG]Environmental Sciences/Global Changes, SEDIMENT, medicine.disease_cause, Monsoon, 01 natural sciences, lcsh:Environmental pollution, Pollen, ETUDE COMPARATIVE, medicine, lcsh:TD169-171.8, TEMPERATURE, Bog, lcsh:Environmental sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, lcsh:GE1-350, Global and Planetary Change, geography, Climate pattern, geography.geographical_feature_category, Anomaly (natural sciences), POLLEN, HUMIDITE DU SOL, Water storage, Paleontology, Edaphic, 15. Life on land, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, MARECAGE, CHANGEMENT CLIMATIQUE, Climatology, GLACIER, lcsh:TD172-193.5, [SDE]Environmental Sciences, ETUDE EXPERIMENTALE, Environmental science, VEGETATION, HUMIDITE DE L'AIR, CHRONOLOGIE, Teleconnection
Abstract

To better characterize the climate variability of the last millennium in the high Andes, we analyzed the pollen content of a 1150-yr-old sediment core collected in a bog located at 3800 m a.s.l. in the páramo in the eastern Cordillera in Ecuador. An upslope convective index based on the ratio between cloud transported pollen from the Andean forest to the bog (T) and Poaceae pollen frequencies, related to the edaphic moisture of the páramo (P), was defined. This index was used to distinguish changes in the atmospheric moisture from the soil moisture content of the páramo and their associated patterns of interdecadal El Niño–Southern Oscillation (ENSO) variability and South American summer monsoon (SASM) activity. Results show that between 850 and 1250 AD, the Medieval Climate Anomaly interval was warm and moist with a high transported pollen/Poaceae pollen (T/P) index linked to high ENSO variability and weak SASM activity. Between 1250 and 1550 AD, a dry climate prevailed, characterized by an abrupt decrease in the T/P index and therefore no upslope cloud convection, related to lower ENSO variability and with significant impact on the floristic composition of the páramo. During the Little Ice Age, two phases were observed: first, a wet phase between 1550 and 1750 AD linked to low ENSO variability in the Pacific and warm south equatorial Atlantic sea surface temperatures (SSTs) favored the return of a wet páramo, and then a cold and dry phase between 1750 and 1800 AD associated with low ENSO variability and weak SASM activity resulted in drying of the páramo. The current warm period marks the beginning of a climate characterized by high convective activity – the highest in the last millennium – and weaker SASM activity modifying the water storage of the páramo. Our results show that the páramo is progressively losing its capacity for water storage and that the interdecadal variability of both tropical Pacific and Atlantic SSTs matter for Andean climate patterns, although many teleconnection mechanisms are still poorly understood.

Published
2013
Full Text
View/download PDF

13. Mid-Holocene climate reconstruction for eastern South America

Author

L. F. Prado, I. Wainer, C. M. Chiessi, M.-P. Ledru, and B. Turcq

Abstract

The Mid-Holocene (6 ka BP) is a key period to the study of climate, since it presented lower than present incoming summer insolation in the Southern Hemisphere, and the opposite in the Northern Hemisphere. This happened due to a different than present configuration of the orbital parameters. To investigate the effects of insolation on the Mid-Holocene climate, some global and regional multiproxy palaeodata compilations have been elaborated. However, few global studies have focused on the Southern Hemisphere, and none of the regional ones have characterized the Mid-Holocene climate in South America through a multiproxy approach. Here we present the first multiproxy compilation to the Mid-Holocene climate in eastern South America. We have compiled 120 palaeoclimatological data, published in 84 different papers. The palaeodata analyzed suggest a water deficit scenario in great part of eastern South America during Mid-Holocene, except for Northeastern Brazil. Nonetheless, further sampling is mandatory in South America and in the adjacent ocean basins.

Published
2012
Full Text
View/download PDF

14. Irregular tropical glacier retreat over the Holocene epoch driven by progressive warming

Author

Delphine Grancher, Régis Braucher, Pierre-Henri Blard, Myriam Khodri, Didier Bourlès, Jean-Emmanuel Sicart, Mathias Vuille, Patrick Wagnon, Daniel Brunstein, Pascale Braconnot, Vincent Jomelli, Vincent Favier, M.-P. Ledru, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), CLIPS, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), CHYC, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-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), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), 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)-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), Department of Atmospheric and Environmental Sciences [Albany] (DAES), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), LEVE, UR Great Ice IRD, European Project, 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), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), 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), 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)-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), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Panthéon-Sorbonne (UP1), 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), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Institut de Recherche pour le Développement (IRD), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, geography, Earth science, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Tidewater glacier cycle, Climate change, Glacier, Glacier morphology, 01 natural sciences, Environmental science, Glacier mass balance, 13. Climate action, Moraine, Climate science, Glacial period, Physical geography, Geology : Geophysics, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Holocene, 0105 earth and related environmental sciences
Abstract

The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate(1) is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions(2). Studies have so far documented extra-tropical glacier fluctuations(3,4), but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a Be-10 chronology for the past 11,000 years (11 kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. Arapid and strong melting from the maximum extent occurred from 10.8 +/- 0.9 to 8.5 +/- 0.4 kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3 +/- 0.8 degrees C cooler at 11 kyr ago and remained -2.1 +/- 0.8 degrees C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics.

Published
2011
Full Text
View/download PDF

15. EGU Alexander von Humboldt conference : the Andes : challenge for geosciences

Author

J. Herreros, F. Delachaux, Ulrich Schotterer, N. Patris, Jean-Denis Taupin, M. De Angelis, Patrick Ginot, Isabel Moreno, M.-P. Ledru, Fabian, P. (ed.), Garreau, R. (ed.), Schneider, C. (ed.), and Tilling, R. (ed.)

Subjects
GLACIOLOGIE, lcsh:Dynamic and structural geology, Tropical Atlantic, PALYNOLOGIE, VOLCANISME, Altitude, lcsh:QE500-639.5, Ice core, Precipitation, ANALYSE ISOTOPIQUE, INTERACTION OCEAN ATMOSPHERE, EL NINO, lcsh:Science, Saddle, Palynology, geography, geography.geographical_feature_category, lcsh:QE1-996.5, Cold wave, General Medicine, lcsh:Geology, Oceanography, Volcano, PALEOCLIMAT, PRECIPITATION, GLACIER, CIRCULATION ATMOSPHERIQUE, lcsh:Q, Geology
Abstract

We investigated past climate variability and the zonal short and long-range transport of air masses in tropical South America using chemical, isotopic and palynological signals from a 42 m-long ice core recovered in 2003 from the saddle of the Nevado Coropuna, southern Peru (72°39´ W; 15°32´ S; 6080 m a.s.l.). We found that precipitation at this site depends mainly on the easterly circulation of air masses originated from the tropical Atlantic Ocean. Nevertheless, sporadic Pacific air masses arrivals, and strong cold waves coming from southern South America reach this altitude site. In spite of post-depositional effects, we were able to identify two strong ENSO (El Niño-Southern Oscillation) event signatures (1982–1983 and 1992) and the eruptive activity of the nearby Sabancaya volcano (1994).

Published
2009

16. Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years

Author

R. Marchant, S. P. Harrison, H. Hooghiemstra, V. Markgraf, J. H. van Boxel, T. Ager, L. Almeida, R. Anderson, C. Baied, H. Behling, J. C. Berrio, R. Burbridge, S. Björck, R. Byrne, M. B. Bush, A. M. Cleef, J. F. Duivenvoorden, J. R. Flenley, P. De Oliveira, B. van Geel, K. J. Graf, W. D. Gosling, S. Harbele, T. van der Hammen, B. C. S. Hansen, S. P. Horn, G. A. Islebe, P. Kuhry, M.-P. Ledru, F. E. Mayle, B. W. Leyden, S. Lozano-García, A. B. M. Melief, P. Moreno, N. T. Moar, A. Prieto, G. B. van Reenen, M. L. Salgado-Labouriau, F. Schäbitz, E. J. Schreve-Brinkman, M. Wille, and Paleoecology and Landscape Ecology (IBED, FNWI)

Abstract

The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small. Patterns of change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America also show a change in biome assignment to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucatán peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation that reflects a generally cool and dry environment. Cool grass/shrubland prevalent in southeast Brazil, Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain forest indicating that forest was present at some locations at the LGM. Some sites in Central México and lowland Colombia remain unchanged in their biome assignments, although the affinities that these sites have to different biomes do change between 18 000±1000 14C yr BP and present. The "unresponsive" nature of these sites results from their location and the impact of local edaphic influence.

Published
2009

17. Millenial-scale climatic and vegetation changes in a northern Cerrado (Northeast, Brazil) since the Last Glacial Maximum

Author

Adauto de Souza Ribeiro, José Antonio López-Sáez, Gregório Ceccantini, Luiz Carlos Ruiz Pessenda, Susy Eli Marques Gouveia, M. P. Ledru, Institut de Recherche pour le Développement (France), Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), López Sáez, José Antonio, and López Sáez, José Antonio [0000-0002-3122-2744]

Subjects
Archeology, Global and Planetary Change, Pleistocene, Desert climate, Ecology, Geology, Last Glacial Maximum, Rainforest, Geography, Deglaciation, Dominance (ecology), Southern Hemisphere, Ecology, Evolution, Behavior and Systematics, Holocene
Abstract

In the Southern Hemisphere, lacustrine sediments started to be deposited with the beginning of the deglaciation at ca 19,000 cal yr BP. At this time the region of Lake Caço was dominated by sparse and shrubby vegetation with dominance of steppic grasses in a poor sandy soil. The landscape did not present any ecological characteristics of a modern Cerrado. However single pollen grains of two Cerrado indicators, Byrsonima and Mimosa, suggest that some Cerrado species were able to survive under the prevailing arid climate, probably as small shrubs. After 15,500 cal yr BP, a sudden increase in the moisture rates is evidenced with the progressive expansion of rainforest showing successive dominance of various associations of taxa. The development of the forest stopped abruptly at the end of the Pleistocene between 12,800 and 11,000 cal yr BP, as attested by strong fires and the expansion of Poaceae. In the early Holocene an open landscape with a relatively high level of water in the lake preceded the progressive expansion of Cerrado species towards a denser forested landscape; fires are recorded from then on, resulting in the physiognomy of the Cerrado we know today. Late Pleistocene paleoenvironmental records from northern Brazil reflect the interplay between insolation forcing of two hemispheres with the local components represented by the interannual shift of the Inter Tropical Convergence Zone and the influence of seasonal equatorwards polar air incursions. © 2005 Elsevier Ltd. All rights reserved., This research benefited from a CNPq (Brazil)–IRD (France) convention and is part of Paléotropique UR 55 at IRD.

Published
2006

18. Climate variability and human impact in South America during the last 2000 years: synthesis and perspectives from pollen records

Author

S. G. A. Flantua, H. Hooghiemstra, M. Vuille, H. Behling, J. F. Carson, W. D. Gosling, I. Hoyos, M. P. Ledru, E. Montoya, F. Mayle, A. Maldonado, V. Rull, M. S. Tonello, B. S. Whitney, and C. González-Arango

Subjects
Environmental pollution, TD172-193.5, Environmental protection, TD169-171.8, Environmental sciences, GE1-350
Abstract

An improved understanding of present-day climate variability and change relies on high-quality data sets from the past 2 millennia. Global efforts to model regional climate modes are in the process of being validated against, and integrated with, records of past vegetation change. For South America, however, the full potential of vegetation records for evaluating and improving climate models has hitherto not been sufficiently acknowledged due to an absence of information on the spatial and temporal coverage of study sites. This paper therefore serves as a guide to high-quality pollen records that capture environmental variability during the last 2 millennia. We identify 60 vegetation (pollen) records from across South America which satisfy geochronological requirements set out for climate modelling, and we discuss their sensitivity to the spatial signature of climate modes throughout the continent. Diverse patterns of vegetation response to climate change are observed, with more similar patterns of change in the lowlands and varying intensity and direction of responses in the highlands. Pollen records display local-scale responses to climate modes; thus, it is necessary to understand how vegetation–climate interactions might diverge under variable settings. We provide a qualitative translation from pollen metrics to climate variables. Additionally, pollen is an excellent indicator of human impact through time. We discuss evidence for human land use in pollen records and provide an overview considered useful for archaeological hypothesis testing and important in distinguishing natural from anthropogenically driven vegetation change. We stress the need for the palynological community to be more familiar with climate variability patterns to correctly attribute the potential causes of observed vegetation dynamics. This manuscript forms part of the wider LOng-Term multi-proxy climate REconstructions and Dynamics in South America – 2k initiative that provides the ideal framework for the integration of the various palaeoclimatic subdisciplines and palaeo-science, thereby jump-starting and fostering multidisciplinary research into environmental change on centennial and millennial timescales.

Published
2016
Full Text
View/download PDF

19. Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

Author

P. A. Baker, S. C. Fritz, C. G. Silva, C. A. Rigsby, M. L. Absy, R. P. Almeida, M. Caputo, C. M. Chiessi, F. W. Cruz, C. W. Dick, S. J. Feakins, J. Figueiredo, K. H. Freeman, C. Hoorn, C. Jaramillo, A. K. Kern, E. M. Latrubesse, M. P. Ledru, A. Marzoli, A. Myrbo, A. Noren, W. E. Piller, M. I. F. Ramos, C. C. Ribas, R. Trnadade, A. J. West, I. Wahnfried, and D. A. Willard

Subjects
Geology, QE1-996.5
Abstract

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results