Download or read book Sub centennial Scale Climatic and Hydrologic Variability in the Gulf of Mexico During the Early Holocene written by Jenna Meredith LoDico and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Sediment core MD02-2550 from Orca Basin located in the northern Gulf of Mexico (GOM) provides a high-resolution early Holocene record of climatic and hydrologic changes from approximately 10.5 to 7 thousand calendar years before present (ka). Paired analyses of Mg/Ca and oxygen isotopes on the planktonic foraminifer Globigerinoides ruber (white variety, 250-355 microns) sampled at approximately 20 remove a comment year resolution were used to generate proxy records of sea surface temperature (SST) and an oxygen isotope record of seawater in the GOM. The Mg/Ca-SST record contains an overall1.5 degree C warming trend from 10.5 to 7 ka that appears to track the intensity of the annual insolation cycle and six temperature oscillations (0.5-2 degree C), the frequency of which are consistent with those found in records of solar variability. The GOM oxygen isotope record contains six approximately 0.5 per mil oscillations from 10.5 to 7 ka that bear some resemblance to regional hydrologic records from Haiti and the Cariaco Basin, plus a -0.8 per mil excursion that may be associated with the "8.2 ka event" recorded in Greenland air temperatures. The GOM oxygen isotope record, if interpreted as a salinity proxy, suggest large salinity fluctuations (greater than 2 psu) reflecting changes in evaporation-precipitation (E-P) and Mississippi River input to the GOM. Percent Globigerinoides sacculifer records from three cores in the GOM exhibit remarkably coherent changes, suggesting episodic centennial-scale incursions of Caribbean waters. Spectral analysis of the Mg/Ca-SST and the GOM oxygen isotope record time series indicate that surface water conditions may be influenced by solar variations because they share significant periods of variability with atmospheric delta 14C near 700, 200, and 80-70 years. Our results add to the growing body of evidence that the sub-tropics were characterized by significant decadal to centennial-scale climatic and hydrologic variability during the early Holocene.
Download or read book A 1400 Year Multi proxy Record of Hydrologic Variability in the Gulf of Mexico written by Jennifer A. Flannery and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Late Holocene climate variability includes the Little Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) that are characterized by contrasting hydrologic and thermal regimes. The degree of interaction between the North American continent and the ocean during these two abrupt climate events is not well known. Marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is ideally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Hydrologic variability recorded over the North America continent is directly dependent on the moisture balance (E/P) over the sub-tropical Gulf of Mexico (a major source of moisture to the North America continent). Warm, moist air masses from the south interact with cold/dry air masses from the north over the North American continent to produce storm fronts. Increased evaporation over the Gulf of Mexico leads to enhanced precipitation over the North American continent, due to the intensification of atmospheric circulation, which influences meridional moisture flux from the Gulf of Mexico to the North American continent. This study focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geochemical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E-P) within the Gulf of Mexico.
Download or read book Centennial scale Sea Surface Temperature and Salinity Variability in the Florida Straits During the Early Holocene written by William Weinlein and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24 degrees 24.70' N, 83 degrees 13.14'W, 198m deep) to reconstruct a high-resolution (~30 yr/sample) early to mid Holocene record of sea surface temperature and delta18OSW (a proxy for SSS) variability. We also measured Ba/Ca ratios in the same shell material as a proxy for riverine input into the Gulf of Mexico over the same time interval. After removing the influence of global delta18OSW change due to continental ice volume variability, we propose that early Holocene SSS enrichments were caused by increased evaporation/precipitation ratios in the Florida Straits associated with periods of reduced solar output, increased ice rafted debris in the North Atlantic and the development of more permanent El Nino-like conditions in the eastern equatorial Pacific. When considered with previous high-resolution reconstructions of early Holocene tropical atmospheric circulation changes, our results provide evidence that solar output variability over the Holocene had a significant impact on the global tropical hydrologic cycle over the last 10,000 years.
Download or read book Surface ocean Variability in the Northern Gulf of Mexico During the Late Holocene written by Kaustubh Ramesh Thirumalai and published by . This book was released on 2016 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface waters of the Gulf of Mexico (GOM) are a major moisture source for North America and play an important role in modulating the hydroclimate of the region. Predictions of future changes in surface-ocean variability in the GOM and hydroclimatic changes in response to greenhouse gas forcing must be placed in context of past changes. However, the instrumental record of sea-surface temperature (SST) and salinity (SSS) observations in the GOM is too brief to examine climate variability on multidecadal-to-centennial timescales; thus, proxy records of SST and SSS variability as encoded in marine sedimentary archives must be used to extract information about climate change on these timescales. In this work, I produce a near-decadal-resolution record of SST and SSS variability in the northern GOM over the last 4,400 years. These paleo-records are based on the measurement of the stable isotopic and trace metal composition of planktic foraminifer Globigerinoides ruber (White) shells in a suite of multicores from the Garrison Basin, northern GOM (26° 40.19'N,93° 55.22'W). The fidelity of this proxy is assessed by performing geochemical measurements on in-situ samples from a nearby sediment trap and by performing statistical data-model comparisons with a foraminiferal forward model that can simulate different calcification depth habitats and seasonal productivity. Next, I construct a computational algorithm that characterizes uncertainty in foraminiferal reconstructions including age, analytical, calibration, ecological, sampling, and preservation errors. The utility of this algorithm is shown by applying it to several previously published records. It is also used to place the new Garrison Basin SST and SSS reconstructions in a quantitative uncertainty framework. I diagnose the controls of multidecadal-to-centennial-scale SST and SSS variability in the GOM (and establish its relationship with Atlantic Ocean circulation) by performing correlation analyses using observations, reanalysis datasets, and transient models. Several other marine and terrestrial proxy records spanning the last millennium are synthesized to document a coordinated linkage between Atlantic Ocean circulation and Western Hemisphere precipitation. This work hypothesizes that a century-scale linkage between ocean circulation and precipitation variability occurred over the last millennium, and perhaps the late Holocene, thereby providing a new perspective on long-term climate change.
Download or read book Integrated Analysis of Interglacial Climate Dynamics INTERDYNAMIC written by Michael Schulz and published by Springer. This book was released on 2014-11-20 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work addresses the following questions in the context of interglacial climate dynamics: (i) What are the amplitudes of natural climate variations on timescales of several years to millennia? (ii) Do abrupt changes in the large-scale circulation of the Atlantic Ocean occur in interglacials? (iii) Which biogeochemical feedback mechanisms control the natural limits of atmospheric concentrations of greenhouse gases and aerosols? (iv) Which linkages exist between climate and pre-industrial cultures? The work is based on an integrated approach in paleoclimate research, in which all available paleoclimate archives (terrestrial and marine as well as ice cores) are combined in order to yield a comprehensive and quantitative analysis of global environmental variations. Moreover, through a close linkage be-tween paleoclimate reconstructions and results from Earth-system models detailed insights into the dynamics of climate variations are gained.
Download or read book Late Holocene Climate Variability from Northern Gulf of Mexico Sediments written by Julie N. Richey and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Accurate reconstruction of natural climate variability over the past millennium is critical for predicting responses to future climate change. In order to improve on current understanding of climate variability in the sub-tropical North Atlantic region over the past millennium, a rigorous study of Gulf of Mexico (GOM) sea surface temperature (SST) variability was conducted using both inorganic (foraminiferal Mg/Ca) and molecular organic (TEX6) geochemical proxies. In addition to generating multiple high-resolution climate records, the uncertainties of the SST proxies are rigorously assessed. There are 3 major research questions addressed: (1) What was the magnitude of GOM SST variability during the past 1,000 years, particularly during large-scale climate events such as the Little Ice Age (LIA) and the Medieval Warm Period (MWP). (2) Is the SST signal reproducible within the same sediment core, among different northern GOM basins, and using different geochemical SST proxies? (3) What are the ecological controls on the paleothermometers used to reconstruct SST variability in the GOM? Can differences in the ecology (i.e. seasonal distribution, depth habitat, etc.) of distinct paleothermometers be exploited to gain insight into changes in upper water column structure or seasonality in the GOM during the LIA and MWP? The major findings include: (1) The magnitude of temperature variability in the GOM over the past millennium is much larger than that estimated from Northern Hemisphere temperature reconstructions. The MWP (1400-900 yrs BP) was characterized by SSTs in the GOM that were similar to the modern SST, while the LIA (400-150 yrs BP) was marked by a series of multidecadal intervals that were 2-2.5°C cooler than modern. (2) This LIA cooling was replicated in the Mg/Ca-SST records from three different well-dated northern GOM basins (Pigmy, Garrison and Fisk Basins), as well as in two different geochemical proxies. (3) It is determined that foraminiferal test size has a significant effect on shell geochemistry. Using core-top calibration, discrepancies in the seasonal/depth habitats between different planktonic Foraminifera, and between Foraminifera and Crenarchaeota are inferred. Downcore differences are used to make inferences about changes in GOM mixed layer depth and seasonality over the past millennium.
Download or read book The Holocene and Anthropocene Environmental History of Mexico written by Nuria Torrescano- Valle and published by Springer Nature. This book was released on 2019-12-02 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides essential information on Mexico’s Holocene and Anthropocene climate and vegetation history. Considering the geography of Mexico – which is home to a variety of climatic and environmental conditions, from desert and tropical to high mountain climates – this book focuses on its postglacial paleoecology and paleoclimatology. Further, it analyses human intervention since the middle Holocene as a major agent of environmental change. Offering a valuable tool for understanding past climate change and its relationship with present climate change, the book is a must-read for botanists, ecologists, palaeontologists and graduate students in related fields.
Download or read book Response of Upper Gulf Coast Estuaries to Holocene Climate Change and Sea level Rise written by John B. Anderson and published by Geological Society of America. This book was released on 2008-01-01 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main impacts of global warming is accelerated sea-level rise: Intergovernmental Panel on Climate Change predictions suggest that the rate of rise could reach as high as 5'10 mm/yr by the end of this century. While it is generally recognized that accelerated sea-level rise will severely impact low-gradient coastlines, scientists are still ill prepared to predict coastal response. A study of seven Gulf Coast estuaries (Mobile Bay and Mississippi Sound, Weeks Bay, Calcasieu Lake, Sabine Lake, Galveston Bay, Matagorda Bay, and Corpus Christi Bay) was aimed at examining their response to past changes in the rate of sea-level rise and climate. The rates of change are of the same magnitude as those predicted for this century. The estuarine response to change has been one of abrupt landward retreat and major reorganization of estuarine environments at decadal time scales. This book should be of interest to scientists and policy makers concerned with future impacts of global warming.
Download or read book Abrupt Climate Change written by Harunur Rashid and published by John Wiley & Sons. This book was released on 2013-05-02 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 193. Abrupt Climate Change: Mechanisms, Patterns, and Impacts brings together a diverse group of paleoproxy records such as ice cores, marine sediments, terrestrial (lakes and speleothems) archives, and coupled ocean-atmosphere climate models to document recent advances in understanding the mechanisms of abrupt climate changes. Since the discovery of the Dansgaard-Oeschger events in Greenland ice cores and the subsequent discovery of their contemporary events in the marine sediments of the North Atlantic, the search for these abrupt, millennial-scale events across the globe has intensified, and as a result, the number of paleoclimatic records chronicling such events has increased. The volume highlights include discussions of records of past climate variability, meridional overturning circulation, land-ocean-atmosphere interactions, feedbacks in the climate system, and global temperature anomalies. Abrupt Climate Change will be of interest to students, researchers, academics, and policy makers who are concerned about abrupt climate change and its potential impact on society.
Download or read book Abrupt Climate Change During the Last Glacial Period written by Heather W. Hill and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Understanding the cause of abrupt climate change in the geologic past can help assess the potential magnitude and variability of future changes in regional and global climate. The research presented here focuses on some of the first records of hydrologic variability in the central North American continent during an interval of Marine Isotope Stage 3 (24-57 thousand years before present (ka)). Sediment core MD02-2551 from the Orca Basin, northern Gulf of Mexico, is used to document the first detailed melting history of the southern margin of the Laurentide Ice Sheet (LIS) during MIS 3, and to record terrestrial inputs from the Mississippi River related to changes in evaporation-precipitation over the mid-continent, from 28-45 ka. Paired measurements of oxygen isotopes and Mg/Ca-SST on the planktonic foraminifera Globigerinoides ruber (pink) are used to calculate the oxygen isotopic composition of seawater and test one of the key hypotheses for abrupt climate change. Five intervals of freshwater input from 28-45 ka do not match the abrupt Dansgaard-Oeschger temperature oscillations recorded in Greenland ice. Rather, summer melting of the LIS may have occurred during Antarctic warming and likely contributed to sea-level variability during MIS 3. A detailed assessment over one of the meltwater events, using the oxygen and carbon isotopic composition of G. ruber and the deeper dwelling Neogloboquadrina dutertrei, demonstrate that meltwater was confined to the surface layers and likely had an impact on the biological pump in the Gulf of Mexico. A similar oxygen isotopic composition of seawater record determined from the year-round white G. ruber suggests that melting was not limited to the warmest summer months. The timing of LIS meltwater input is decoupled from an interval of enhanced wet conditions over the North American continent and increased Mississippi River discharge, as shown by a suite of organic and sedimentologic proxies. Increasing summer insolation on the orbital scale may have led to a northward migration of the Intertropical Convergence Zone and an intensification and westward shift in the conical position of the Bermuda High, which shuttles moisture to the North American continent and contributes to flooding in the Mississippi River drainage basin.
Download or read book eha tsne lekhet written by and published by . This book was released on 2001* with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sea Level Change in the Gulf of Mexico written by Richard A. Davis and published by Texas A&M University Press. This book was released on 2011-05-18 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: A must-read for Gulf Coast scientists, naturalists, and residents . . . From Florida to Mexico and along the shores of Cuba, the coasts of the Gulf of Mexico are vulnerable to sea-level rise because of their fragile and low-lying shorelines and adjacent coastal environments. In addition to wetlands, river deltas, beaches, and barrier islands, millions of people who live and work along the Gulf coast are susceptible to the affects of both intense storms in the short term and a gradual rise in sea level over the longer term. While global warming headlines any current discussion of this topic and is certainly a major factor in sea-level change, it is not the only factor. Earthquakes and other crustal shifts, the El Niño/La Niña phenomena, river impoundment and sedimentation, tides, and weather can all affect local, regional, and global sea levels. In Sea-Level Change in the Gulf of Mexico, Richard A. Davis Jr. looks at the various causes and effects of rising and falling sea levels in the Gulf of Mexico, beginning with the Gulf’s geological birth over 100 million years ago, and focusing on the last 20,000 years, when global sea levels began rising as the glaciers of the last major ice age melted. Davis reviews the current situation, especially regarding beach erosion and loss of wetlands, and offers a preview of the future, when the Gulf Coast will change markedly as the twenty-first century progresses. Amply illustrated and written in a clear, straightforward style, Sea-Level Change in the Gulf of Mexico is a valuable resource for anyone who cares deeply about understanding the past, present, and future of life along the coast of the Gulf of Mexico.
Download or read book Orbital to Millennial scale Variability in Gulf of Mexico Sea Surface Temperature and Salinity During the Late Pleistocene written by Jessica L. Whitaker and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial rise in GOM SST at 132.1 ka of 2.9 °C is followed by a cold reversal of 1.5 °C at 130.4 ka for 2 ky and final increase to full interglacial warmth. The reversal in GOM SST is consonant with a pause in sea level rise and reduced NADW, suggesting a reduction in THC may have caused a global two-step deglaciation.
Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Gulf of Mexico Origin Waters and Biota written by Noreen A. Buster and published by Texas A&M University Press. This book was released on 2011-05-30 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 3 of Gulf of Mexico Origin, Waters, and Biota; a series edited by John W. Tunnell Jr., Darryl L. Felder, and Sylvia A. Earle A continuation of the landmark scientific reference series from the Harte Research Institute for Gulf of Mexico Studies, Gulf of Mexico Origin, Waters, and Biota, Volume 3, Geology provides the most up-to-date, systematic, cohesive, and comprehensive description of the geology of the Gulf of Mexico Basin. The six sections of the book address the geologic history, recent depositional environments, and processes offshore and along the coast of the Gulf of Mexico. Scientific research in the Gulf of Mexico region is continuous, extensive, and has broad-based influence upon scientific, governmental, and educational communities. This volume is a compilation of scientific knowledge from highly accomplished and experienced geologists who have focused most of their careers on gaining a better understanding of the geology of the Gulf of Mexico. Their research, presented in this volume, describes and explains the formation of the Gulf Basin, Holocene stratigraphic and sea-level history, energy resources, coral reefs, and depositional processes that affect and are represented along our Gulf coasts. It provides valuable synthesis and interpretation of what is known about the geology of the Gulf of Mexico. Five years in the making, this monumental compilation is both a lasting record of the current state of knowledge and the starting point for a new millennium of study.
Download or read book Freshwater Inflow Action Agenda for the Gulf of Mexico written by Gulf of Mexico Program (U.S.) and published by . This book was released on 1994 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tropical Rainforest Responses to Climatic Change written by Mark B. Bush and published by Springer Science & Business Media. This book was released on 2007 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this book is to provide a current overview of the impacts of climate change on tropical forests, to investigate past, present, and future climatic influences on the ecosystems with the highest biodiversity on the planet.Tropical Rainforest Responses to Climatic Change will be the first book to examine how tropical rain forest ecology is altered by climate change, rather than simply seeing how plant communities were altered. Shifting the emphasis onto ecological processes e.g. how diversity is structured by climate and the subsequent impact on tropical forest ecology, provides the reader with a more comprehensive coverage. A major theme of this book that emerges progressively is the interaction between humans, climate and forest ecology. While numerous books have appeared dealing with forest fragmentation and conservation, none have explicitly explored the long term occupation of tropical systems, the influence of fire and the future climatic effects of deforestation, coupled with anthropogenic emissions. Incorporating modelling of past and future systems paves the way for a discussion of conservation from a climatic perspective, rather than the usual plea to stop logging.
