Download or read book Millennial scale Climate Variability in North America During the Past 14 000 Years written by Andre Ernest J. Viau and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variations in the Earth's climate occur on many time and space scales. A recent focus of paleoclimate research is the so-called 1500-year North Atlantic quasi-periodic cycle, and has revolved around three main themes. First, what are the underlying causes and physical mechanisms governing these millennial-scale variations? Next, are they global or restricted to certain sensitive regions of the planet? Last, what is the magnitude of the temperature changes of these variations, and do they vary in time and space? This dissertation explores millennial-scale climate variability in North America during the past 14,000 years using a dense network of fossil pollen data, which is used as proxy for climate variations. Three independent approaches are used to quantify these changes. A mixture modelling analysis of radiocarbon dates on pollen transitions, a principal component analysis of pollen diagrams from all of North America, and a mean July temperature reconstruction based on the method of modern analogue (MAT) all reveal millennial-scale climate variability throughout North America during the past 14,000 years. The identified transitions generally correlate well with other proxy-climate records from the North Atlantic region. However, certain mismatches occurred particularly at 9, 6 and 4 ka BP. If we assume the dominant millennial-scale period is 1150-years, the records become more consistent. North American temperature variability was not unidirectional nor uniformly distributed in space, suggesting large-scale ocean-atmospheric reorganizations at the transitions. Correlation between the proxy-climate and cosmogenic nuclide records supports a variable solar output hypothesis as the fundamental cause for century to millennial-scale climate variability. The mean July temperature of North America varied on the order of 0.2 to 0.4°C during the Holocene and 0.4° and 0.6°C during the deglaciation. Temperature was more variable during the late glacial, possibly due to the impact on the climate of massive meltwater pulses into the North Atlantic, further amplified through ocean dynamic processes. Recent global warming estimated as an increase in temperature of 0.4--0.6°C, is therefore greater than the estimated natural variation of the past 10,000 years, providing further evidence that recent increases in atmospheric CO2 have played a major role in modern warming.
Download or read book Millenial scale Climate Variability in North America During the Past 14 000 Years written by André E. Viau and published by . This book was released on 2003 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms of Global Climate Change at Millennial Time Scales written by Lloyd D. Keigwin and published by American Geophysical Union. This book was released on 1999-01-26 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contributors describe the current understanding of abrupt climate variations that have occurred at millennial to submillennial time scales, events now recognized as characteristics of the global climate during the last glaciation. Subjects covered include analysis of modern climate and ocean dynamics, paleoclimate reconstructions derived from the marine, terrestrial and ice core records, and paleoclimate modeling studies. The breadth of global paleoclimate knowledge presented here provides information required to answer many questions and provides a road map to address remaining problems. Most material is from a June 1998 conference. Lacks a subject index. Annotation copyrighted by Book News, Inc., Portland, OR.
Download or read book Climate Change in North America written by George Ohring and published by Springer Science & Business Media. This book was released on 2014-02-12 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes thoroughly the North American Climate of the past 65 million years, with special emphasis on the last 21,000 years, as revealed by paleoclimatic observations and climate models. It analyzes weather observations over the past century and satellite measurements of the last few decades to develop a picture of more recent climatic trends. It explains how global climate models are used to simulate and project climate, and presents the application of these models to reproduce recent climate variations and predict future North American climate. It answers the critical question of whether observed climate change is due to natural variations or human activity.
Download or read book Global Environmental Change written by National Research Council and published by National Academies Press. This book was released on 1999-09-14 with total page 621 pages. Available in PDF, EPUB and Kindle. Book excerpt: How can we understand and rise to the environmental challenges of global change? One clear answer is to understand the science of global change, not solely in terms of the processes that control changes in climate and the composition of the atmosphere, but in how ecosystems and human society interact with these changes. In the last two decades of the twentieth century, a number of such research effortsâ€"supported by computer and satellite technologyâ€"have been launched. Yet many opportunities for integration remain unexploited, and many fundamental questions remain about the earth's capacity to support a growing human population. This volume encourages a renewed commitment to understanding global change and sets a direction for research in the decade ahead. Through case studies the book explores what can be learned from the lessons of the past 20 years and what are the outstanding scientific questions. Highlights include: Research imperatives and strategies for investigators in the areas of atmospheric chemistry, climate, ecosystem studies, and human dimensions of global change. The context of climate change, including lessons to be gleaned from paleoclimatology. Human responses toâ€"and forcing ofâ€"projected global change. This book offers a comprehensive overview of global change research to date and provides a framework for answering urgent questions.
Download or read book Climatic and Ecological Change in the Americas written by James Andrew Whitaker and published by Taylor & Francis. This book was released on 2023-08-17 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a comparative analysis of the experiences, responses, and adaptations of people to climate variability and environmental change across the Americas. It foregrounds historical ecology as a structural framework for understanding the climate change crisis throughout the region and throughout time. In recent years, Indigenous and local populations in particular have experienced climate change effects such as altered weather patterns, seasonal irregularities, flooding and drought, and difficulties relating to subsistence practices. Understanding and dealing with these challenges has drawn on peoples’ longstanding experience with climate variability and in some cases includes models of mitigation and responses that are millennia old. With contributions from specialists across the Americas, this volume will be of interest to scholars from fields including anthropology, archaeology, geography, environmental studies, and Indigenous studies.
Download or read book Millennial scale Variability to 735 Ka written by Sarah Marie White and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Determining the ultimate cause and effect of millennial-scale climate variability remains an outstanding problem in paleoclimatology, partly due to the lack of high-resolution records extending beyond the last glacial period. New cores from Santa Barbara Basin provide ~5000 year "windows" of climate with ~50-year resolution dating to ~293 ka (the MIS 8.6-8.5 transition), ~460 ka (MIS 12), and ~735 ka (MIS 18). These records span the Late Pleistocene, during which the 100-kyr cycle gained power in global climate records and the magnitude of glacial-interglacial cyclicity increased. Thus, these records provide a test of the dependence of millennial-scale behavior on variations in glacial-interglacial cyclicity. Planktonic foraminiferal [delta]18O indicates that millennial-scale variability is present in all three intervals, and is similar to that during MIS 3. Stadial G. bulloides [delta]18O values were 2.75-1.75 per mil (mean 2.25 per mil) and interstadial values were 1.75- 0.5 per mil (mean 1 per mil), with rapid interstadial initiations of 1-2 per mil, as in MIS 3. Interstadials were ~300-1300 years long and spaced ~750-1500 years apart, consistent with MIS 3 interstadial durations. Upwelling increased during interstadials, but did not vary synchronously with surface water temperatures, again similar to MIS 3. These high- resolution records provide evidence that millennial-scale variability was an inherent feature of glacial climates in the Northern Hemisphere throughout the past 735 ka.
Download or read book Second Assessment of Climate Change for the Baltic Sea Basin written by The BACC II Author Team and published by Springer. This book was released on 2015-04-03 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an update of the first BACC assessment, published in 2008. It offers new and updated scientific findings in regional climate research for the Baltic Sea basin. These include climate changes since the last glaciation (approx. 12,000 years ago), changes in the recent past (the last 200 years), climate projections up until 2100 using state-of-the-art regional climate models and an assessment of climate-change impacts on terrestrial, freshwater and marine ecosystems. There are dedicated new chapters on sea-level rise, coastal erosion and impacts on urban areas. A new set of chapters deals with possible causes of regional climate change along with the global effects of increased greenhouse gas concentrations, namely atmospheric aerosols and land-cover change. The evidence collected and presented in this book shows that the regional climate has already started to change and this is expected to continue. Projections of potential future climates show that the region will probably become considerably warmer and wetter in some parts, but dryer in others. Terrestrial and aquatic ecosystems have already shown adjustments to increased temperatures and are expected to undergo further changes in the near future. The BACC II Author Team consists of 141 scientists from 12 countries, covering various disciplines related to climate research and related impacts. BACC II is a project of the Baltic Earth research network and contributes to the World Climate Research Programme.
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 Decade to Century Scale Climate Variability and Change written by National Research Council and published by National Academies Press. This book was released on 1998-12-24 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Society today may be more vulnerable to global-scale, long-term, climate change than ever before. Even without any human influence, past records show that climate can be expected to continue to undergo considerable change over decades to centuries. Measures for adaption and mitigation will call for policy decisions based on a sound scientific foundation. Better understanding and prediction of climate variations can be achieved most efficiently through a nationally recognized "dec-cen" science plan. This book articulates the scientific issues that must be addressed to advance us efficiently toward that understanding and outlines the data collection and modeling needed.
Download or read book Natural Climate Variability on Decade to Century Time Scales written by National Research Council and published by National Academies Press. This book was released on 1996-08-30 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Climate of Past Interglacials written by F. Sirocko and published by Elsevier. This book was released on 2006-12-08 with total page 639 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, climate fluctuations, such as the Little Ice Age, show that interglacial climate chage in not entirely stable, but responds to even subtle changes in radiative forcing. Through research, it has been made clear that even an abrupt change of climate within years is not just a theoretical possibility but has in fact happened in the prehistoric past. It is therefore clear that in principal it could happen again. Human civilaization has exploded under the mild and relatively stable climatic conditions that have prevailed over the last 11,000 years. This book focuses on revisiting the past and to study climate and environment in a suite of experiments where boundary conditions are similar but not identical to today so we can learn about the climate-environment system, its sensitivity, thresholds and feedback. The palaeoclimate community holds an important key to scientific information on climate change that provides a basis for appropriate adaptation and mitigation strategies. The authors of this book have taken up this challenge and summarize their results in this special volume. It presents state-of-the-art science on new reconstructions from all spheres of the Earth System and on their synthesis, on methodological advances, and on the current ability of numerical models to simulate low and high frequency changes of climate, environment, and chemical cycling related to interglacials.* Summarizes important information on climate change, providing a basis for appropriate adaptation and mitigation strategies for human civilization* Reports on new reconstuctions on methodological advances, numerical models simulating low and high frequence changes, and chemical cycling related to interglacials* Incorporates palaeovegetaion and numerical modeling of climate and environmental and geochemical parameters to address regional feedback to global change with successful data-models
Download or read book The First Rung written by Hamid Rafizadeh and published by Archway Publishing. This book was released on 2018-05-21 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: What can the long-dead ancients tell us about our future? Plenty, according to sacred texts and modern science. While the modern person has only witnessed one celestial state of the earth, ancient peoples have witnessed two. Science calls these two versions glacial and interglacial earth, but to the ancients they are the blue-skied earth and the canopied earth. And as the earth positions to once again flip to its yet unknown secondary state, we can turn to the ancients for answers. The First Rung weaves together the stories of humanitys epic struggle to understand the past in order to understand the presentand most importantly, to understand the future. This fascinating account provides eye-opening insight into the mix of ancient and modern knowledge that defines the earths celestial environment, and author Hamid Rafizadeh offers a tour of the evidence regarding the earths two different versionsdetails of which our ancient human ancestors have seen. By bringing echoes of the past into the present, we can have an intellectual awakening of the knowledge that holds the answers for humanitys survival and well-being. The unknown, hidden past of the ancients haunts the modern humans life; it is a dangerous shadow cast on everyone, but it is also a knowledge not to be missed.
Download or read book Past Climate Variability in South America and Surrounding Regions written by Francoise Vimeux and published by Springer Science & Business Media. This book was released on 2009-08-04 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: South America is a unique place where a number of past climate archives are ava- able from tropical to high latitude regions. It thus offers a unique opportunity to explore past climate variability along a latitudinal transect from the Equator to Polar regions and to study climate teleconnections. Most climate records from tropical and subtropical South America for the past 20,000 years have been interpreted as local responses to shift in the mean position and intensity of the InterTropical Conv- gence Zone due to tropical and extratropical forcings or to changes in the South American Summer Monsoon. Further South, the role of the Southern Hemisphere westerly winds on global climate has been highly investigated with both paleodata and coupled climate models. However the regional response over South America during the last 20,000 years is much more variable from place to place than pre- ously thought. The factors that govern the spatial patterns of variability on millennial scale resolution are still to be understood. The question of past natural rates and ranges of climate conditions over South America is therefore of special relevance in this context since today millions of people live under climates where any changes in monsoon rainfall can lead to catastrophic consequences.
Download or read book Millennial Scale Climate Variability During the Last 6000 Years Tracking Down the Bond Cycles written by Jonathan Bütikofer and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Millennial scale Climate Variability During Glacial Interglacial and Transitional Climate States written by Kevin George Cannariato and published by . This book was released on 2002 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Historical Climate Variability and Impacts in North America written by Lesley-Ann Dupigny-Giroux and published by Springer. This book was released on 2010-04-29 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climatologists with an eye on the past have any number of sources for their work, from personal diaries to weather station reports. Piecing together the trajectory of a weather event can thus be a painstaking process taking years and involving real detective work. Missing pieces of a climate puzzle can come from very far afield, often in unlikely places. In this book, a series of case studies examine specific regions across North America, using instrumental and documentary data from the 17th to the 19th centuries. Extreme weather events such as the Sitka hurricane of 1880 are recounted in detail, while the chapters also cover more widespread phenomena such as the collapse of the Low Country rice culture. The book also looks at the role of weather station histories in complementing the instrumental record, and sets out the methods that involve early instrumental and documentary climate data. Finally, the book’s focus on North America reflects the fact that the historical climate community there has only grown relatively recently. Up to now, most such studies have focused on Europe and Asia. The four sections begin with regional case studies, and move on to reconstruct extreme events and parameters. This is followed by the role of station history and, lastly, methodologies and other analyses. The editors’ aim has been to produce a volume that would be instrumental in molding the next generation of historical climatologists. They designed this book for use by general researchers as well as in upper-level undergraduate or graduate level courses.
