Download or read book Response of Interior North America to Abrupt Climate Oscillations in the the North Atlantic Region During the Last Deglaciation written by and published by . This book was released on 2001 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Megafaunal Extinctions at the End of the Pleistocene written by Gary Haynes and published by Springer Science & Business Media. This book was released on 2008-12-23 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume contains summaries of facts, theories, and unsolved problems pertaining to the unexplained extinction of dozens of genera of mostly large terrestrial mammals, which occurred ca. 13,000 calendar years ago in North America and about 1,000 years later in South America. Another equally mysterious wave of extinctions affected large Caribbean islands around 5,000 years ago. The coupling of these extinctions with the earliest appearance of human beings has led to the suggestion that foraging humans are to blame, although major climatic shifts were also taking place in the Americas during some of the extinctions. The last published volume with similar (but not identical) themes -- Extinctions in Near Time -- appeared in 1999; since then a great deal of innovative, exciting new research has been done but has not yet been compiled and summarized. Different chapters in this volume provide in-depth resumés of the chronology of the extinctions in North and South America, the possible insights into animal ecology provided by studies of stable isotopes and anatomical/physiological characteristics such as growth increments in mammoth and mastodont tusks, the clues from taphonomic research about large-mammal biology, the applications of dating methods to the extinctions debate, and archeological controversies concerning human hunting of large mammals.
Download or read book Patterns Mechanisms and Legacies of Abrupt Climate Change written by David Fastovich and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing global temperatures from anthropogenic greenhouse gas emissions are driving widespread climatological and ecological changes globally. Abrupt global changes that share rates of climate change similar to those experienced today (Overpeck et al. 2003; Williams and Burke 2019) are recorded throughout the geologic record and offer important insights that can help predict future anthropogenic change. The Deglacial period (19,000 to 11,000 years before present) after the Last Glacial Maximum has been a key interval for understanding ecological and climatological responses to increasing greenhouse gas concentrations and a warming climate (COHMAP Project Members 1988; Nolan et al. 2018; Mottl et al. 2021). Imposed on this gradual warming are abrupt climate oscillations that onset within decades to centuries, last for millennia, and are commonly attributed to changes in the Atlantic meridional overturning circulation forced by the input of freshwater into the North Atlantic Ocean. The most recent of these millennial-scale climate events is the Younger Dryas (ca. 12,900 to 11,700 years before present) and caused spatially complex climate changes globally. In this dissertation, we first aim to determine the spatial patterns of climate change and the atmospheric mechanisms responsible for driving abrupt climate change regionally in eastern North America through the use of organic temperature biomarkers (brGDGTs) and climate models. Second, we seek to disentangle the contributions of glacial and millennial-scale climate variability upon modern patterns of species richness in eastern North America. Chapter 2 seeks to determine the spatial fingerprint of Younger Dryas temperature changes in eastern North America. We develop a spatially dense multiproxy network of temperature reconstructions relying upon statistical transfer functions applied to fossil-pollen abundances and an independent proxy, based on organic biomarkers (brGDGTs). This analysis indicates that temperature changes during the Younger Dryas followed a dipole pattern in eastern North America. Temperatures lowered abruptly in maritime Canada and the northeastern United States nearly synchronously with temperature records from Greenland (Severinghaus et al. 1998). Cooling is also reconstructed in the Great Lakes region but delayed by ~400 years. Sites south of 35℗ʻN exhibited an antiphased response and lack YD cooling, with Florida sites indicating a thermal maximum. Warming in Florida during the Younger Dryas suggests that the 'bipolar-seesaw' conceptualization is an oversimplification of the spatial patterns of global climate changes. Focus must be placed on constraining regional climate changes to refine the mechanisms of abrupt climate change. Chapter 3 aims to better understand the atmospheric mechanisms for these antiphased temperature changes in eastern North America. We accomplish this by combining our multiproxy temperature network with a synthesis of hydroclimate reconstructions to compare against four climate models with meltwater hosing experiments that resemble the onset of the Younger Dryas. Precipitation changes followed a tripole pattern with wetting in the northeastern United States and Florida and drying from the Great Lakes region to the Carolinas, in contrast to the temperature dipole resolved in Chapter 2. Analysis of the climate models highlights the dual role of ice sheets and meltwater-induced weakening of the Atlantic meridional overturning circulation as the key drivers of the reconstructed warming and wetting in the southeastern United States. Reduced northward oceanic heat transport in the Atlantic Ocean increased the latitudinal temperature gradient and strengthened the jet stream, leading to upper-level divergence over eastern North America and the transport of warmer and moister air into the southeastern United States. For Chapter 4, we use our multiproxy temperature and precipitation reconstruction from prior chapters, alongside 11 climate simulations of millennial- scale climate events forced by meltwater pulses, to assess whether legacies of these climate changes can be detected in the contemporary diversity of amphibians, birds, mammals, reptiles, and trees in eastern North America. Generalized additive models that use both contemporary and paleoclimatic predictors suggest that past millennial scale climate oscillations have left an imprint on contemporary amphibian and arboreal biodiversity, though the exact role of past climate changes remains uncertain. Generalized additive models that use the multiproxy network of Younger Dryas climate reconstructions and a subset of the climate models analyzed suggest that greater millennial scale climate variability is predictive of greater contemporary biodiversity. However, generalized additive models that use four of the climate models suggest that millennial-scale climate stability is predictive of greater contemporary richness in eastern North America. Disagreement in the sign, magnitude, and spatial fingerprint of climate changes among the 11 climate simulations and the multiproxy climate reconstructions precludes further refining the role of millennial-scale climate oscillations at this time. This uncertainty highlights that caution should be used when attempting to model contemporary biodiversity based on individual paleoclimatic simulations. Higher resolution climate simulations forced with accurate boundary conditions are necessary to constrain the relationship between past millennial-scale climate changes and contemporary biodiversity.
Download or read book Sheguiandah Site written by Patrick J. Julig and published by University of Ottawa Press. This book was released on 2002-01-01 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: First excavated in the early 1950s, the Sheguiandah site had remained enigmatic for half a century. This volume details controversial early claims that the site had been occupied before the last Ice Age, then covers more recent studies of the geological and botanical history of the area – including new evidence that the site was uninhabited until after the retreat of the glaciers.
Download or read book Global Change in the Holocene written by John Birks and published by Routledge. This book was released on 2014-02-24 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Holocene spans the 11,500 years since the end of the last Ice Age and has been a period of major global environmental change. However the rate of change has accelerated during the last hundred years, due largely to human impacts and this has led to a growing concern for the future of our environmental resources. Global Change in the Holocene demonstrates how reconstructing the record of past environmental change can provide us with essential knowledge about how our environment works and presents the reader with an informed viewpoint from which to project realistic future scenarios. The book brings together key techniques that are widely used in Holocene research, such as radiocarbon dating, dendrochronology and sediment analysis and offers a comprehensive analysis of various archives of environmental change including instrumental and documentary records, corals, lake sediments, glaciers and ice cores. This reference will be an informative and cutting-edge resource for all researchers in the fields of climate change, environmental science, geography, palaeoecology and archaeology.
Download or read book Hunter Gatherer Behavior written by Metin I Eren and published by Routledge. This book was released on 2016-05-23 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume addresses key questions regarding the extent of the Younger Dryas climate event at the end of the Pleistocene and how hunter-gatherer populations worldwide adapted behaviorally and technologically in the face of major climatic change.
Download or read book Reconstructing Quaternary Environments written by J. John Lowe and published by Routledge. This book was released on 2014-10-28 with total page 1031 pages. Available in PDF, EPUB and Kindle. Book excerpt: This third edition of Reconstructing Quaternary Environments has been completely revised and updated to provide a new account of the history and scale of environmental changes during the Quaternary. The evidence is extremely diverse ranging from landforms and sediments to fossil assemblages and geochemical data, and includes new data from terrestrial, marine and ice-core records. Dating methods are described and evaluated, while the principles and practices of Quaternary stratigraphy are also discussed. The volume concludes with a new chapter which considers some of the key questions about the nature, causes and consequences of global climatic and environmental change over a range of temporal scales. This synthesis builds on the methods and approaches described earlier in the book to show how a number of exciting ideas that have emerged over the last two decades are providing new insights into the operation of the global earth-ocean-atmosphere system, and are now central to many areas of contemporary Quaternary research. This comprehensive and dynamic textbook is richly illustrated throughout with full-colour figures and photographs. The book will be of interest to undergraduates, postgraduates and professionals in Earth Science, Environmental Science, Physical Geography, Geology, Botany, Zoology, Ecology, Archaeology and Anthropology
Download or read book Assessment of Species Diversity in the Atlantic Maritime Ecozone written by Donald F. McAlpine and published by NRC Research Press. This book was released on 2010 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book First Peoples in a New World written by David J. Meltzer and published by Cambridge University Press. This book was released on 2021-10-07 with total page 497 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 15,000 years ago, a band of hunter-gatherers became the first people to set foot in the Americas. They soon found themselves in a world rich in plants and animals, but also a world still shivering itself out of the coldest depths of the Ice Age. The movement of those first Americans was one of the greatest journeys undertaken by ancient peoples. In this book, David Meltzer explores the world of Ice Age Americans, highlighting genetic, archaeological, and geological evidence that has revolutionized our understanding of their origins, antiquity, and adaptation to climate and environmental change. This fully updated edition integrates the most recent scientific discoveries, including the ancient genome revolution and human evolutionary and population history. Written for a broad audience, the book can serve as the primary text in courses on North American Archaeology, Ice Age Environments, and Human evolution and prehistory.
Download or read book Encyclopedia of Quaternary Science written by and published by Elsevier. This book was released on 2006-11-24 with total page 7184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quaternary sciences constitute a dynamic, multidisciplinary field of research that has been growing in scientific and societal importance in recent years. This branch of the Earth sciences links ancient prehistory to modern environments. Quaternary terrestrial sediments contain the fossil remains of existing species of flora and fauna, and their immediate predecessors. Quaternary science plays an integral part in such important issues for modern society as groundwater resources and contamination, sea level change, geologic hazards (earthquakes, volcanic eruptions, tsunamis), and soil erosion. With over 360 articles and 2,600 pages, many in full-color, the Encyclopedia of Quaternary Science provides broad ranging, up-to-date articles on all of the major topics in the field. Written by a team of leading experts and under the guidance of an international editorial board, the articles are at a level that allows undergraduate students to understand the material, while providing active researchers with the latest information in the field. Also available online via ScienceDirect (2006) – featuring extensive browsing, searching, and internal cross-referencing between articles in the work, plus dynamic linking to journal articles and abstract databases, making navigation flexible and easy. For more information, pricing options and availability visit www.info.sciencedirect.com. 360 individual articles written by prominent international authorities, encompassing all important aspects of quaternary science Each entry provides comprehensive, in-depth treatment of an overview topic and presented in a functional, clear and uniform layout Reference section provides guidence for further research on the topic Article text supported by full-color photos, drawings, tables, and other visual material Writing level is suited to both the expert and non-expert
Download or read book The Quaternary Period in the United States written by A.R. Gillespie and published by Elsevier. This book was released on 2003-12-17 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews advances in understanding of the past ca. two million years of Earth history - the Quaternary Period - in the United States. It begins with sections on ice and water - as glaciers, permafrost, oceans, rivers, lakes, and aquifers. Six chapters are devoted to the high-latitude Pleistocene ice sheets, to mountain glaciations of the western United States, and to permafrost studies. Other chapters discuss ice-age lakes, caves, sea-level fluctuations, and riverine landscapes. With a chapter on landscape evolution models, the book turns to essays on geologic processes. Two chapters discuss soils and their responses to climate, and wind-blown sediments. Two more describe volcanoes and earthquakes, and the use of Quaternary geology to understand the hazards they pose. The next part of the book is on plants and animals. Five chapters consider the Quaternary history of vegetation in the United States. Other chapters treat forcing functions and vegetation response at different spatial and temporal scales, the role of fire as a catalyst of vegetation change during rapid climate shifts, and the use of tree rings in inferring age and past hydroclimatic conditions. Three chapters address vertebrate paleontology and the extinctions of large mammals at the end of the last glaciation, beetle assemblages and the inferences they permit about past conditions, and the peopling of North America. A final chapter addresses the numerical modeling of Quaternary climates, and the role paleoclimatic studies and climatic modeling has in predicting future response of the Earth's climate system to the changes we have wrought.
Download or read book Folsom written by David J. Meltzer and published by Univ of California Press. This book was released on 2006-06-05 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the late 1920s an exciting discovery was made at the New Mexico site of Folsom - spear points, found embedded between the ribs of an Iron Age bison - that was to resolve decades of bitter conflict amongst archaeologists.
Download or read book Northern Forestry Centre Publications written by Northern Forestry Centre (Canada) and published by . This book was released on 2000 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abrupt Climate Change written by National Research Council and published by National Academies Press. This book was released on 2002-04-23 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human society and ecosystems, including major impacts on energy consumption and water supply demands. Could such a change happen again? Are human activities exacerbating the likelihood of abrupt climate change? What are the potential societal consequences of such a change? Abrupt Climate Change: Inevitable Surprises looks at the current scientific evidence and theoretical understanding to describe what is currently known about abrupt climate change, including patterns and magnitudes, mechanisms, and probability of occurrence. It identifies critical knowledge gaps concerning the potential for future abrupt changes, including those aspects of change most important to society and economies, and outlines a research strategy to close those gaps. Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.
Download or read book Geochemistry and Paleohydrology of Groundwater dominated Lakes of the Ovando Valley Montana written by Shapley Mark Dallas and published by . This book was released on 2005 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Abrupt Deglacial Climate Changes in the North Pacific and Implications for Climate Tipping Points written by Summer Kate Praetorius and published by . This book was released on 2014 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paleoclimate archives have revealed abrupt climate events that are superimposed on more gradual climate changes throughout the last glacial and deglacial periods. The underlying causes of such rapid climate changes are still poorly understood, but the strong expression of these events in northern hemisphere records likely points to climatic mechanisms of a northern origin. A leading hypothesis for the trigger of these climate fluctuations has been changes in the strength of the Atlantic meridional overturning circulation (AMOC). However, the very rapid nature of some of the observed climate transitions (3-50 years) suggests a potential role for abrupt shifts in atmospheric circulation or nonlinear feedbacks within the climate system. Understanding the relative timing and magnitude of these events in different regions of the globe will help to identify the sources and possible amplifying mechanisms that have led to abrupt climate changes in the past, which will provide insight and constraints on the potential for abrupt climate changes in the future. This dissertation seeks to characterize climate changes occurring in the Northeast Pacific during the last deglaciation, a time period that encompasses the dynamic transition between the last ice age and the modern day interglacial period. So far, high-resolution records with precise chronologies from the North Pacific have been sparse, and paleoclimate models and proxy reconstructions disagree about the deglacial climate changes that are both predicted and observed to have occurred in this region. Marine sediment records from the Gulf of Alaska (GOA) have exceptionally high resolution (~1 cm/yr), making it possible to reconstruct climate changes in unprecedented detail for the North Pacific region. We establish new multi-decadal scale records of surface ocean variability using planktonic oxygen isotopes and sea-surface temperature (SST) estimates based on the alkenone U3--[superscript K'] unsaturation index, as well as regional records of ice-rafting and deglacial volcanic activity sourced from the Mt. Edgecumbe volcanic field (MEVF). The age models for these records are constrained by high-precision radiocarbon dating, tephra correlation, and "tuning" to the decadal-scale North Greenland Ice Core Project (NGRIP) oxygen isotope record. We combine new and previously published data from a depth transect of marine sites in the GOA and Northeast Pacific to place surface ocean changes in context of oceanic variability throughout the water column. These reconstructions are then used to evaluate three fundamental questions: 1) what are the timing and patterns of deglacial climate changes in the North Pacific relative to other regions, 2) what are the potential forcing mechanisms for deglacial climate variability in this region, and 3) how does the subsurface ocean respond to and influence abrupt climate change. In chapter two, we compare the timing and patterns of climate changes occurring between the North Pacific and North Atlantic regions. A major debate in the paleoclimate literature has been whether these regions operate in a synchronized or seesaw like mode. We compare the high resolution GOA and NGRIP oxygen isotope records as proxies for local temperature, and find that both synchronous and asynchronous climate patterns occur between regions throughout the past 18,000 years. The most abrupt climate transitions are preceded/accompanied by synchronous behavior, whereas times of relative climate stability exhibit asynchronous or anticorrelated (seesaw) patterns. This implies that coupling of North Pacific and North Atlantic heat transport could act as an amplifying mechanism in abrupt northern hemisphere climate change, whereas opposing oceanic regimes could act to balance northern hemisphere heat transport, and thus promote climate stability. In chapter three, we examine the timing between regional deglaciation and volcanism to evaluate potential feedbacks between climate and volcanic activity. Although volcanic eruptions have been observed to contribute to abrupt climate fluctuations with global effects in historical times, the role of volcanic forcing in climate variability of the more distant past (prior to the Holocene) has been neglected due to the very short-time scales in which volcanic events occur, and the difficulty of obtaining records with high enough resolution to capture these events and their associated climate effects. We evaluate the source and timing of a sequence of 23 tephra layers preserved in high-accumulation rate sediment cores proximal to the MEVF, and examine the regional climate response to this volcanic activity through comparison with reconstructions of sea surface temperatures, oxygen isotopes, and the [delta]18O of seawater. We find that the onset of enhanced volcanic activity coincides with abrupt warming at the onset of the Bølling Allerød, regional retreat of glaciers, and a period of rapid vertical land motion predicted from a model of regional isostatic rebound. These finding support the hypothesis that deglaciation may promote volcanism by removing crustal loading. The records of sea surface variability show large fluctuations during the episode of intense volcanic activity, suggesting that deglacial volcanic activity may not only respond to climate, but may also contribute to climate variance during the deglacial interval. In Chapter four, we examine the oceanographic changes that lead to two episodes of hypoxia in the GOA that lasted for millennia during the deglaciation. Similar hypoxic events have been documented across the North Pacific, indicating a widespread expansion of the oxygen minimum zone (OMZ) during the Bølling Allerød and early Holocene warm periods. These episodes have been linked to enhanced export productivity in many sites, however, the driving mechanisms for enhanced productivity and ocean deoxygenation remain elusive. Our alkenone temperature reconstructions reveal two abrupt warmings of 4-5°C that precisely coincide with the onset of increased export productivity and a sudden shift to hypoxic conditions, suggesting a strong link between ocean warming, marine productivity, and deoxygenation. Oxygen isotopes throughout the water column indicate that a transient subsurface warming of ~2°C might have accompanied the first hypoxic event during the BA. We propose that abrupt ocean warming lead to an expansion of the North Pacific OMZ through a reduction in oxygen solubility, enhanced thermal stratification, and a stimulation of marine productivity through the stabilization of the euphotic zone (related to stratification), combined with enhanced nutrient input from remobilization of iron in hypoxic shelf sediments. These studies indicate that large surface and subsurface ocean changes occurred in the North Pacific during the last deglaciation, with the potential for important feedbacks on global climate.
Download or read book Abrupt Climate Events During the Last Deglaciation and Media Audience Perception of Climate Change written by Elizabeth A. Obbink and published by . This book was released on 2009 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
