Dynamique climatique de l'Océan Pacifique ouest équatorial au cours du Pléistocène récent PDF Download

Author: Thibault de Garidel-Thoron
Publisher:
ISBN:
Category :
Languages : fr
Pages : 161

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Book Description
L'océan Pacifique ouest équatorial, la zone la plus chaude du globe, est impliquée dans le système méridien de mousson et celui zonal d'El Nino-Oscillation Australe. En utilisant les assemblages des foraminifères planctoniques et coccolithophoridés, microfossiles carbonatés, leurs compositions isotopiques et leurs morphométries, nous avons reconstruit la dynamique climatique de cette zone au Pléistocène récent. Dans cet intervalle, les températures de surface varient entre 27 et 29.5ʿC. Un mécanisme de balancement de la thermocline des océans Indo-Pacifique similaire à l'ENSO, lié aux cycles orbitaux de précession est décrit. Des changements rapides du climat sont également observés dans le Pacifique ouest, et mis en liaison avec les événements de Dansgaard/Oeschger des hautes latitudes. Des relargages abrupts de gaz-hydrates de méthane observés dans le Pacifique ouest sont suggérés jouer un rôle majeur dans l'amplification globale de la dynamique climatique à l'échelle du millénaire.

Author: P. Giresse
Publisher: Elsevier
ISBN: 0080556035
Category : Science
Languages : en
Pages : 407

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Book Description
West Africa and the eastern Atlantic stretching from Mauritania in the north to Namibia in the south offer a large latitudinal stretch incorporating nearly symmetrical climatic gradients from the Equator. On the time scale of Quaternary Glacial and Interglacial cycles, today, we possess well-documented and recently published marine sedimentary records showing changes in oceanic and atmospheric circulations and terrestrial fluxes. Deep-sea sediment records contain a wide range of palaeoenvironmental indicators like oxygen and carbon isotopes, alkenones, foraminiferal and other planktonic assemblages over time periods up to and greater than 125,000 years. These are signals of temperature and circulation shifts and allow Interglacial and Glacial comparisons on a regional and inter-hemispheric scale. However, this effort to synthesize the existing knowledge cannot yet aspire to a global modelling. Linking with terrestrial records, albeit spatially patchy and generally lacking a firm chronology, this book points to shorter time scale chronologies from lakes, marshes and river deposits. Diverse and not very wellknown literature, both French and English, is reported here. Lastly, the book records recent knowledge of the first steps of human occupation of frequently hostile environments and considers the environmental impact of ancient and modern societies.* Covers the recent studies about marine Quaternary environments off West Africa, as well as continental Quaternary environments of tropical and sub-tropical West Africa (over 10,000 to 100,000 years)* Compares the parallel between palae-oenvironmental trends according to latitudinal gradients

Author: Intergovernmental Panel on Climate Change (IPCC)
Publisher: Cambridge University Press
ISBN: 9781009157971
Category : Science
Languages : en
Pages : 755

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Book Description
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

Author:
Publisher:
ISBN:
Category : Earth sciences
Languages : en
Pages : 50

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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309054494
Category : Science
Languages : en
Pages : 645

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Book Description
This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. It covers a wide range of relevant subjects, including the characteristics of the atmosphere and ocean environments as well as the methods used to describe and analyze them, such as proxy data and numerical models. They clearly demonstrate the range, persistence, and magnitude of climate variability as represented by many different indicators. Not only do natural climate variations have important socioeconomic effects, but they must be better understood before possible anthropogenic effects (from greenhouse gas emissions, for instance) can be evaluated. A topical essay introduces each of the disciplines represented, providing the nonscientist with a perspective on the field and linking the papers to the larger issues in climate research. In its conclusions section, the book evaluates progress in the different areas and makes recommendations for the direction and conduct of future climate research. This book, while consisting of technical papers, is also accessible to the interested layperson.

Author: Intergovernmental Panel on Climate Change
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: M. N. Rajeevan
Publisher: Springer
ISBN: 9811025312
Category : Science
Languages : en
Pages : 326

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Book Description
The objective of the book is to make a comprehensive documentation of the observed variability and change of the regional climate system over the Indian region using the past observed data. The book addresses all the important parameters of regional climate system so that a physically consistent view of the changes of the climate system is documented. The book contains 16 chapters written by the subject experts from different academic and research institutes in India. The book addresses all important components/parameters of the climate system, like rainfall, temperature, humidity, clouds, moisture, sea surface temperature and ocean heat content, sea level, glaciers and snow cover, tropical cyclones and monsoon depressions, extreme rainfall and rainstorms, heat waves and cold waves, meteorological droughts, aerosols, atmospheric aerosols, ozone and trace gases and atmospheric radiative fluxes. One chapter deals with the past monsoon using monsoon proxy data. The last chapter deals with the future climate change projections over the Indian region (rainfall and temperature) made using coupled climate models. Most of the analyses (especially on rainfall, temperature, extreme rainfall, sea surface temperature, meteorological droughts) are based on the data for a longer period of 110 years, 1901–2010. For some other parameters like moisture, clouds, heat waves and cold waves, atmospheric aerosols, ozone and trace gases and radiative fluxes, data of shorter period have been used. The articles documented inter-annual and decadal variability in addition to documenting long term trends of different parameters. The trends have been tested for statistical significance using standard techniques. It is expected that the present book will be an excellent reference material for researchers as well as for policy makers. These results will be useful in interpreting future climate change scenarios over the region being projected using coupled climate models. Further analysis of these results is required for attributing the observed variability and change to natural and anthropogenic activities.

Author: Jürgen Runge
Publisher: CRC Press
ISBN: 1000431150
Category : Science
Languages : en
Pages : 412

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Book Description
This book celebrates the relaunch of the African Pollen Database, presents state-of-the-art of modern and ancient pollen data from sub-Saharan Africa, and promotes Open Access science. Pollen grains are powerful tools for the study of past vegetation dynamics because they preserve well within sedimentary deposits and have a huge diversity in ornamentation that allows different taxa to be determined. The reconstruction of past vegetation from the examination of ancient pollen records thus can be used to characterize the nature of past landscapes (e.g. abundance of forests vs. grasslands), provide insights into changes in biodiversity, and gain empirical evidence of vegetation response to climatic change and human activity. In this, the 35th Volume of "Palaeoecology of Africa", we bring together new data and extensive synthetic reviews to provide novel insights into the relationships between human evolution, human activity, climate change and vegetation dynamics during the Quaternary, the last 2.6 million years. Current and ongoing climate and land-use change is exerting pressure on modern vegetation formations and threatening the livelihoods and wellbeing of many peoples in Africa. In this book the focus is on the Quaternary because it is during this geological period that the modern vegetation formations developed into their current configurations against a backdrop of high magnitude global climate change (glacial-interglacial cycles), human evolution, and a growing human land-use footprint. In this book the latest information is presented and collated from around the African continent to parameterize past vegetation states, identify the drivers of vegetation change, and assess the vegetation resilience to change. To achieve this research from two broad themes are covered: (i) the present is the key to the past (i.e. studies which improve our understanding of modern environments so that we can better interpret evidence from the past), and (ii) the past is the key to the future (i.e. studies which unlock information on how and why vegetation changed in the past so one can better anticipate trajectories of future change). This Open Access book will provide a strong foundation for future research exploring past ecological, environmental and climatic change within Africa and the surrounding islands. The book is organized regionally (covering western, eastern, central, and southern Africa) and it contains specialized articles focused on particular topics (such as modern pollen-vegetation relationships and fire as a driver of vegetation change), as well as regional and pan-African syntheses drawing together decades of research to assess key scientific questions (including the role of climate in driving vegetation change and the role of vegetation change in human evolution). These articles will be useful to students and teachers from high school to the highest level of university who are interested in the origins and dynamics of vegetation in Africa. Furthermore, it is also meant to provide societally relevant information that can act as an inspiration for the development of sustainable management practices for the future.

Author: Henry N. Houérou
Publisher: Springer Science & Business Media
ISBN: 3540851925
Category : Science
Languages : en
Pages : 252

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Book Description
Covering an area of over 130 million km2 spanning the Mediterranean, equator and tropics, the African continent features a spectacular geographic diversity. Consequently, it is characterised by extremely variable climatic, edaphic and ecological conditions, associated with a wide range of natural vegetation and wildlife, as well as human population density, crops and livestock. In this book, Henry Le Houérou presents his bioclimatic and biogeographic classification of Africa. The extensive data provide the basis for comparisons between various African regions, and with regions on other continents such as Latin America or the Indian subcontinent. The results constitute a rational basis for national, regional and sub-regional rural development planning, and for agricultural research dealing with aspects such as plant and animal introductions, the extrapolation or interpolation of experimental or developmental findings, and ecosystems dynamics. Possible problems of applications are also examined.

Author: Michael J.R. Fasham
Publisher: Springer Science & Business Media
ISBN: 3642558445
Category : Science
Languages : en
Pages : 324

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Book Description
Oceans account for 50% of the anthropogenic CO2 released into the atmosphere. During the past 15 years an international programme, the Joint Global Ocean Flux Study (JGOFS), has been studying the ocean carbon cycle to quantify and model the biological and physical processes whereby CO2 is pumped from the ocean's surface to the depths of the ocean, where it can remain for hundreds of years. This project is one of the largest multi-disciplinary studies of the oceans ever carried out and this book synthesises the results. It covers all aspects of the topic ranging from air-sea exchange with CO2, the role of physical mixing, the uptake of CO2 by marine algae, the fluxes of carbon and nitrogen through the marine food chain to the subsequent export of carbon to the depths of the ocean. Special emphasis is laid on predicting future climatic change.