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Author:
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 232
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Book Description
The Cenozoic climate record derived from the oxygen isotope ratios of benthic foraminifera (delta18Ob) displays several, short term steps signifying the glaciation of Antarctica (~33.7 Ma) and the development (~2.7 Ma) and intensification (~0.9 Ma) of large-scale northern hemisphere glaciation (NHG), termed hereafter the late Pliocene transition (LPT) and mid-Pleistocene transition (MPT), respectively. The interpretation of the delta18Ob record, which is controlled by both temperature and the oxygen isotopic composition of seawater (delta, omega), is, however, not straightforward. In the work presented here, I:(1) used Mg/Ca benthic foraminiferal paleothermometry paired with delta18Ob to construct high resolution records of deep ocean temperature and global ice volume to understand the underlying mechanisms of Pliocene-Pleistocene climate transitions and (2) developed a new salinity independent paleothermometer based on Sr/Ca ratios in marine gastropods and examined its potential for Cenozoic low-latitude sea surface temperature reconstructions and I constructed and applied a new regional Mg/Ca-temperature calibration based on downcore Mg/Ca variations to encompass changes in temperature and carbonate saturation in deep Atlantic Ocean. The new, high resolution bottom water temperature record from North Atlantic Deep Sea Drilling Project site 607 indicates that the deep ocean cooled across both the LPT and MPT. The cooling across the MPT preconditioned the high latitudes for ice-sheet growth by modifying heat transport through changes in meridional temperature gradients. Across the LPT, the mean trend in sea level decreased by 20+/-25m whereas the MPT is associated with an increase in glacial-interglacial amplitude of sea level. I propose that the MPT is related to a change in ice sheet dynamics, specifically growth of thicker ice sheets, and that a threshold response to high-latitude cooling is not sufficient to explain the MPT. The Sr/Ca- temperature calibration study, based on the marine gastropod Conus ermineus, shows that strontium incorporation into the aragonitic gastropod shell is most likely driven by a temperature influence on growth rate. To minimize the ontogenetic effect, I separated the Sr/Ca-temperature calibration into juvenile and adult growth stages. The application of the new low-latitude paleothermometer to fossil specimens shows that the low latitudes cooled along with high latitudes throughout the Cenozoic.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309209196
Category : Science
Languages : en
Pages : 153
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Book Description
There is little dispute within the scientific community that humans are changing Earth's climate on a decadal to century time-scale. By the end of this century, without a reduction in emissions, atmospheric CO2 is projected to increase to levels that Earth has not experienced for more than 30 million years. As greenhouse gas emissions propel Earth toward a warmer climate state, an improved understanding of climate dynamics in warm environments is needed to inform public policy decisions. In Understanding Earth's Deep Past, the National Research Council reports that rocks and sediments that are millions of years old hold clues to how the Earth's future climate would respond in an environment with high levels of atmospheric greenhouse gases. Understanding Earth's Deep Past provides an assessment of both the demonstrated and underdeveloped potential of the deep-time geologic record to inform us about the dynamics of the global climate system. The report describes past climate changes, and discusses potential impacts of high levels of atmospheric greenhouse gases on regional climates, water resources, marine and terrestrial ecosystems, and the cycling of life-sustaining elements. While revealing gaps in scientific knowledge of past climate states, the report highlights a range of high priority research issues with potential for major advances in the scientific understanding of climate processes. This proposed integrated, deep-time climate research program would study how climate responded over Earth's different climate states, examine how climate responds to increased atmospheric carbon dioxide and other greenhouse gases, and clarify the processes that lead to anomalously warm polar and tropical regions and the impact on marine and terrestrial life. In addition to outlining a research agenda, Understanding Earth's Deep Past proposes an implementation strategy that will be an invaluable resource to decision-makers in the field, as well as the research community, advocacy organizations, government agencies, and college professors and students.
Author:
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 232
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Book Description
The Cenozoic climate record derived from the oxygen isotope ratios of benthic foraminifera (delta18Ob) displays several, short term steps signifying the glaciation of Antarctica (~33.7 Ma) and the development (~2.7 Ma) and intensification (~0.9 Ma) of large-scale northern hemisphere glaciation (NHG), termed hereafter the late Pliocene transition (LPT) and mid-Pleistocene transition (MPT), respectively. The interpretation of the delta18Ob record, which is controlled by both temperature and the oxygen isotopic composition of seawater (delta, omega), is, however, not straightforward. In the work presented here, I:(1) used Mg/Ca benthic foraminiferal paleothermometry paired with delta18Ob to construct high resolution records of deep ocean temperature and global ice volume to understand the underlying mechanisms of Pliocene-Pleistocene climate transitions and (2) developed a new salinity independent paleothermometer based on Sr/Ca ratios in marine gastropods and examined its potential for Cenozoic low-latitude sea surface temperature reconstructions and I constructed and applied a new regional Mg/Ca-temperature calibration based on downcore Mg/Ca variations to encompass changes in temperature and carbonate saturation in deep Atlantic Ocean. The new, high resolution bottom water temperature record from North Atlantic Deep Sea Drilling Project site 607 indicates that the deep ocean cooled across both the LPT and MPT. The cooling across the MPT preconditioned the high latitudes for ice-sheet growth by modifying heat transport through changes in meridional temperature gradients. Across the LPT, the mean trend in sea level decreased by 20+/-25m whereas the MPT is associated with an increase in glacial-interglacial amplitude of sea level. I propose that the MPT is related to a change in ice sheet dynamics, specifically growth of thicker ice sheets, and that a threshold response to high-latitude cooling is not sufficient to explain the MPT. The Sr/Ca- temperature calibration study, based on the marine gastropod Conus ermineus, shows that strontium incorporation into the aragonitic gastropod shell is most likely driven by a temperature influence on growth rate. To minimize the ontogenetic effect, I separated the Sr/Ca-temperature calibration into juvenile and adult growth stages. The application of the new low-latitude paleothermometer to fossil specimens shows that the low latitudes cooled along with high latitudes throughout the Cenozoic.
Author: Fabio Florindo
Publisher: Elsevier
ISBN: 0080931618
Category : Science
Languages : en
Pages : 606
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Book Description
Antarctic Climate Evolution is the first book dedicated to furthering knowledge on the evolution of the world’s largest ice sheet over its ~34 million year history. This volume provides the latest information on subjects ranging from terrestrial and marine geology to sedimentology and glacier geophysics. An overview of Antarctic climate change, analyzing historical, present-day and future developments Contributions from leading experts and scholars from around the world Informs and updates climate change scientists and experts in related areas of study
Author: Vivien Gornitz
Publisher: Springer Science & Business Media
ISBN: 1402045514
Category : Science
Languages : en
Pages : 1062
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Book Description
One of Springer’s Major Reference Works, this book gives the reader a truly global perspective. It is the first major reference work in its field. Paleoclimate topics covered in the encyclopedia give the reader the capability to place the observations of recent global warming in the context of longer-term natural climate fluctuations. Significant elements of the encyclopedia include recent developments in paleoclimate modeling, paleo-ocean circulation, as well as the influence of geological processes and biological feedbacks on global climate change. The encyclopedia gives the reader an entry point into the literature on these and many other groundbreaking topics.
Author: Manfred Mudelsee
Publisher: Springer Science & Business Media
ISBN: 9048194822
Category : Science
Languages : en
Pages : 497
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Book Description
Climate is a paradigm of a complex system. Analysing climate data is an exciting challenge, which is increased by non-normal distributional shape, serial dependence, uneven spacing and timescale uncertainties. This book presents bootstrap resampling as a computing-intensive method able to meet the challenge. It shows the bootstrap to perform reliably in the most important statistical estimation techniques: regression, spectral analysis, extreme values and correlation. This book is written for climatologists and applied statisticians. It explains step by step the bootstrap algorithms (including novel adaptions) and methods for confidence interval construction. It tests the accuracy of the algorithms by means of Monte Carlo experiments. It analyses a large array of climate time series, giving a detailed account on the data and the associated climatological questions. This makes the book self-contained for graduate students and researchers.
Author: Max Johan Holmstrom
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Donald R. Prothero
Publisher: Cambridge University Press
ISBN: 0521433878
Category : Science
Languages : en
Pages : 708
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Book Description
Provides the latest information in dating and correlation of the strata of late middle Eocene through early Oligocene age in North America.
Author: Yuanyuan Sun
Publisher: Open Dissertation Press
ISBN: 9781361376706
Category :
Languages : en
Pages :
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Book Description
This dissertation, "Cenozoic Climatic and Environmental Changes in the Qaidam Basin" by Yuanyuan, Sun, 孙嫒嫒, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Large discrepancies remain regarding the timing of Cenozoic paleoclimatic and paleoenvironmental transitions in the central Asia. The first order driving force behind these changes has been intensively debated. Global climate change, the uplift of Tibetan Plateau, and the evolution of Paratethys sea have been proposed as three major candidates. To understand the evolutionary history of climate and environment of the region and controlling factors responsible for these paleoclimatic and paleoenvironmental changes, a combined study utilizing multiple proxies, including microfossils, bulk carbonate carbon and oxygen isotopes, long chain alkenones, plant n-alkane-based indices (carbon preference index, average chain length and Paq) and compound-specific carbon and hydrogen isotopes of higher plant n-alkanes, was carried out on a long, continuous and well-dated section in Dahonggou, Qaidam Basin, northern Tibetan Plateau. A parallel study was also carried out in another relatively shorter section in the Xunhua Basin, northern Tibetan Plateau. Six intervals of paleoclimatic and paleoenvironmental transitions over an interval of 35 Myr can be recognized in the studied sections, including Late Eocene-Early Oligocene gradual drying (prior to 30 Ma), Middle Oligocene aridification ( 30-26 Ma), Late Oligocene-Early Miocene wetting ( 26-21 Ma), Early Miocene drying ( 21-17 Ma), Middle Miocene climatic optimum ( 17-13 Ma), and deteriorated climate since the late Middle Miocene ( 13 Ma onwards). The reconstructed onsite C4 plant abundance including occurrence of C4 plants and their thriving and the followed decreasing, a sensitive indicator of available moisture level in the environment, agrees well with these intervals. Microfossils and long-chain alkenones suggest that a relic sea existed in the Qaidam Basin during the Middle Miocene, thus falsifying any hypothesis of significant variations in elevations of northern Tibetan Plateau prior to the Middle Miocene. The relatively stable elevations since the Eocene and before the Middle Miocene of, respectively, the central-southern part and northern part of the Plateau reveals an insignificant role of Tibetan Plateau uplift in controlling the evolution of central Asian climate and environment during the early Cenozoic. However, the Middle Miocene marine transgression and the rapid plateau-scale uplift since the late Middle Miocene probably contributed to the Middle Miocene climatic optimum and the initiated aridification afterwards in the central Asia. A comparison of proxy records in the northern Tibetan Plateau with the global benthic oxygen isotope record suggests a tight relation between the climatic/environmental transitions in the central Asia and global climatic changes. This lends support to the hypothesis that global climate, by controlling the moisture supply to the continental interior, played the dominant role in the evolution of climate and environment of central Asia during the Cenozoic time. DOI: 10.5353/th_b5223961 Subjects: Climatic changes - China - Tsaidam Basin Paleoclimatology - Cenozoic
Author: Mark Williams
Publisher: Geological Society of London
ISBN: 9781862392403
Category : Nature
Languages : en
Pages : 604
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Author: Irena Ivanovna Borzenkova
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages :
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