Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Records Of Oceanic And Continental Response To Abrupt Climate Changes During The Late Holocene 2000bp Present From The Pigmy Basin Gulf Of Mexico
Download Records Of Oceanic And Continental Response To Abrupt Climate Changes During The Late Holocene 2000bp Present From The Pigmy Basin Gulf Of Mexico full books in PDF, epub, and Kindle. Read online Records Of Oceanic And Continental Response To Abrupt Climate Changes During The Late Holocene 2000bp Present From The Pigmy Basin Gulf Of Mexico ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Records of Oceanic and Continental Response to Abrupt Climate Changes During the Late Holocene (2,000BP-present) from the Pigmy Basin, Gulf of Mexico by : Jennifer A. Flannery
Download or read book Records of Oceanic and Continental Response to Abrupt Climate Changes During the Late Holocene (2,000BP-present) from the Pigmy Basin, Gulf of Mexico written by Jennifer A. Flannery and published by . This book was released on 2005 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A 1400 Year Multi-proxy Record of Hydrologic Variability in the Gulf of Mexico by : Jennifer A. Flannery
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.
Book Synopsis Response of Upper Gulf Coast Estuaries to Holocene Climate Change and Sea-level Rise by : John B. Anderson
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.
Book Synopsis Abrupt Climate Change During the Last Glacial Period by : Heather W. Hill
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.
Book Synopsis The Oceans and Rapid Climate Change by : Dan Seidov
Download or read book The Oceans and Rapid Climate Change written by Dan Seidov and published by John Wiley & Sons. This book was released on 2001-01-09 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 126. Until a few decades ago, scientists generally believed that significant large-scale past global and regional climate changes occurred at a gradual pace within a time scale of many centuries or millennia. A secondary assumption followed: climate change was scarcely perceptible during a human lifetime. Recent paleoclimatic studies, however, have proven otherwise: that global climate can change extremely rapidly. In fact, there is good evidence that in the past at least regional mean annual temperatures changed by several degrees Celsius on a time scale of several centuries to several decades.
Book Synopsis Late Holocene Climate Variability from Northern Gulf of Mexico Sediments by : Julie N. Richey
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.
Book Synopsis Surface-ocean Variability in the Northern Gulf of Mexico During the Late Holocene by : Kaustubh Ramesh Thirumalai
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.
Book Synopsis Heinrich Events by : Thomas G. Andrews
Download or read book Heinrich Events written by Thomas G. Andrews and published by . This book was released on 2000* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rapid Climate Change Recorded in the North Pacific by : Ingrid Hendy
Download or read book Rapid Climate Change Recorded in the North Pacific written by Ingrid Hendy and published by . This book was released on 2000 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Planktonic foraminiferal isotopic and faunal evidence is presented from a Californian Margin transect (ODP Holes 893A, Santa Barbara Basin; 1O17E, San Lucia Slope; and 1014, Tanner Basin) for major climate instability during the latest Quaternary. Differences between all three sites suggest a dramatic response to rapid climate change on the southern Californian Margin inferring relative changes in the contribution of surface water masses via the California Current System produced the large SST changes in the region. Southern California margin surface water conditions recorded by planktonic faunal oscillations also suggest variations in thermocline depth, vertical structure and temperature gradient between interstadials and stadials. Top-down, in situ atmospheric warming of the ocean is implied by differential responses (partial decoupling) in the changes recorded in surface and thermoclinal waters. Surface water conditions demonstrate the rapid response of the California Current System to reorganisation of North Pacific atmospheric circulation during rapid climate change suggesting a bimodal stability in North Pacific surface-ocean circulation organisation. Synchronous climatic response between north Pacific surface waters and the Greenland ice sheet during D/O cycling is strongly indicated by remarkable similarities in speed, magnitude and character of rapid oceanic and atmospheric reorganizations. As ocean-atmosphere interactions over the North Pacific determine strength and location of surface currents, it follows some global climatic signals were atmospherically transmitted. The oscillatory pattern of climate change during 01S 3 suggests at this time the climate system was close to a threshold, whereby small perturbations were amplified to produce major, rapid climate change. Santa Barbara Basin benthic oscillations demonstrate North Pacific Intermediate Water temperature instability during submillennial climate change confirming changes in thermohaline circulation. Comparison of benthic and planktonic records provide evidence of differences in temporal response of surface and intermediate waters to rapid climate change. Gradual warming of upper intermediate water compared to abrupt atmospherically transmitted surface water warming suggests mechanistic differences not evident at abrupt coolings. Comparisons suggest North Pacific intermediate water warming preceded the abrupt surface warming by up to 200 years implying a previously undocumented feedback process in the climate system"--Leaf viii.
Book Synopsis Sub-centennial Scale Climatic and Hydrologic Variability in the Gulf of Mexico During the Early Holocene by : Jenna Meredith LoDico
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.
Book Synopsis Oceanic and Atmospheric Response to Climate Change Over Varying Geologic Timescales by : Stella Woodard
Download or read book Oceanic and Atmospheric Response to Climate Change Over Varying Geologic Timescales written by Stella Woodard and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Global climate is controlled by two factors, the amount of heat energy received from the sun (solar insolation) and the way that heat is distributed Earth's surface. Solar insolation varies on timescales of 10s to 100s of thousands of years due to changes in the path of Earth's orbit about the sun (Milankovitch cycles). Earth's internal boundary conditions, such as paleogeography, the presence/absence of polar icecaps, atmospheric/oceanic chemistry and sea level, provide distribution and feedback mechanisms for the incoming heat. Variations in these internal boundary conditions may happen abruptly or, as in the case of plate tectonics, take millions of years. We use geochemical and sedimentological techniques to investigate the response of ocean chemistry, regional aridity and atmospheric and oceanic circulation patterns to climate change during both greenhouse and icehouse climates. To explore the connection between orbitally-forced changes in solar insolation, continental aridity and wind, we generated a high-resolution dust record for ~58 Myr old deep-sea sediments from Shatsky Rise. Our data provide the first evidence of a correlation between dust flux to the deep sea and orbital cycles during the Early Paleogene, indicating dust supply (regional aridity) responded to orbital forcing during the last major interval of greenhouse climate. The change in dust flux was comparable to that during icehouse climates implying subtle variations in solar insolation have a similar impact on climate during intervals of over-all warmth as they do during glacial-interglacial states. The Carboniferous Period (359-299 Ma) marks a critical time in Earth's history when a series of tectonic and biological events caused a shift in the mean climate state from a global "greenhouse" to an "icehouse". Geochemical records extracted from sedimentary rocks deposited in shallow epicontinental seaways are increasingly being used to infer relationships between tectonism, carbon cycling and climate and therefore are assumed to reflect global ocean processes. We analyzed radiogenic isotopes in biogenic apatite along a North American transect to constrain the degree of geochemical coupling between the epicontinental seas and the open ocean. Our results argue strongly for decoupling of North American seaways from the open ocean by latest Mississippian time.
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :0309475848 Total Pages :157 pages Book Rating :4.3/5 (94 download)
Book Synopsis Understanding the Long-Term Evolution of the Coupled Natural-Human Coastal System by : National Academies of Sciences, Engineering, and Medicine
Download or read book Understanding the Long-Term Evolution of the Coupled Natural-Human Coastal System written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2018-11-17 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Gulf Coast provides a valuable setting to study deeply connected natural and human interactions and feedbacks that have led to a complex, interconnected coastal system. The physical landscape in the region has changed significantly due to broad-scale, long-term processes such as coastal subsidence and river sediment deposition as well as short-term episodic events such as hurricanes. Modifications from human activities, including building levees and canals and constructing buildings and roads, have left their own imprint on the natural landscape. This coupled natural-human coastal system and the individual aspects within it (physical, ecological, and human) are under increased pressure from accelerating environmental stressors such as sea level rise, intensifying hurricanes, and continued population increase with its accompanying coastal development. Promoting the resilience and maintaining the habitability of the Gulf Coast into the future will need improved understanding of the coupled natural-human coastal system, as well as effective sharing of this understanding in support of decision-making and policies. Understanding the Long-term Evolution of the Coupled Natural-Human Coastal System presents a research agenda meant to enable a better understanding of the multiple and interconnected factors that influence long-term processes along the Gulf Coast. This report identifies scientific and technical gaps in understanding the interactions and feedbacks between human and natural processes, defines essential components of a research and development program in response to the identified gaps, and develops priorities for critical areas of research.
Book Synopsis Evidence of Abrupt Climate Change in the Gulf of Mexico During the Last Glaciation by : Charles S. Adams
Download or read book Evidence of Abrupt Climate Change in the Gulf of Mexico During the Last Glaciation written by Charles S. Adams and published by . This book was released on 2012 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Pleistocene and Holocene Hydroclimate Change in the Southeastern United States by : James Joseph Kocis
Download or read book Late Pleistocene and Holocene Hydroclimate Change in the Southeastern United States written by James Joseph Kocis and published by . This book was released on 2011 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to understand hydroclimate variability of future climate change, it is important to know the timing and range of natural climate change in the past. The Southeastern United States (SE) is situated along the poleward extent of projected subtropical drying, where the expression of past hydrological balances remains unclear. The lack of high-resolution paleohydroclimate records in the SE forces climate modelers to base interpretations on better-understood regions of North America. The SE likely experienced significant changes in precipitation regimes resulting from its position at the convergence of several oceanic and continental air masses. To reconstruct precipitation variability, this study examines multiple floodplains along the Tennessee River as hydroclimate proxy archives in the SE. Changes in precipitation balances are interpreted from high-resolution trends in sedimentary, pedogenic, and stable carbon datasets that span the last 14 ka BP (kiloannum before present). Variation in overbank sedimentation, identified from grain-size trends indicate precipitation increased from 11.0-8.0 ka BP. During this pluvial interval, stable carbon isotope values of soil organic matter in floodplain paleosols show negative excursions (~1.0-1.5 permil) from average modern values. A period of aridity, evident from an overall excursion to less negative stable carbon isotope values, increased abundance of fine-grain sizes, and increased paleosol development occurs between 8.0-5.0 ka BP. Most notably, the transition out of the mid-Holocene (~5.0 ka BP) is marked by an abrupt change to more negative carbon isotope values (~1.5 permil). Wavelet analysis of composite sedimentary and stable carbon isotope data time series indicate statistically significant (p[less than or equal to]0.1) 200- to 500-yr and ~1000-yr periodicities. Periods of aridity in the SE are correlated with the eastward intensification of the North Atlantic Subtropical High (NASH). Pluvial conditions result from the westward intensification of the NASH. The timing of wet and dry periods recorded by floodplain paleosol is in agreement with the onset and frequency of such changes observed in regional records. The floodplain datasets presented here provide the first long-term record of the onset and duration of centennial-scale changes in precipitation that occurred during the late Pleistocene and Holocene in the SE.
Book Synopsis The Geologic Record of Climatic Change by : Thomas J. Crowley
Download or read book The Geologic Record of Climatic Change written by Thomas J. Crowley and published by . This book was released on 1982 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Abrupt Climate Change in the Atlantic Ocean During the Last 20,000 Years: Insights from Multi-Element Analyses of Benthic and Planktic Foraminifera and a Coupled OA-GCM. by :
Download or read book Abrupt Climate Change in the Atlantic Ocean During the Last 20,000 Years: Insights from Multi-Element Analyses of Benthic and Planktic Foraminifera and a Coupled OA-GCM. written by and published by . This book was released on 2005 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Minor and trace element records from planktic and benthic foraminifera from Atlantic sediment cores, as well as output from a coupled OA-GCM, were used to investigate the magnitude and distribution of the oceanic response to abrupt climate events of the past 20,000 years. The study addressed three major questions: 1) What is the magnitude of high-latitude sea surface temperature and salinity variability during abrupt climate events? 2) Does intermediate depth ventilation change in conjunction with high-latitude climate variability? 3) Are the paleoclimate data consistent with the response of a coupled OA-GCM to a freshwater perturbation? To address these questions, analytical methods were implemented for the simultaneous measurement of Mg/Ca, Zn/Ca, Cd/Ca, Mn/Ca and Al/Ca in foraminiferal samples using inductively-coupled plasma mass spectrometry. Paired records of planktic foraminiferal deltaO18 and Mg/Ca from the subpolar North Atlantic reveal trends of increasing temperatures ( -3 deg C) and salinities over the course of the Holocene. The records provide the first evidence of open-ocean cooling (nearly 2 deg C) and freshening during the 8.2 kyr event, and suggest similar conditions at 9.3ka. Benthic foraminiferal Cd/Ca results from an intermediate depth, western South Atlantic core (1,268m) are consistent with reduced export into the S. Atlantic of N. Atlantic Intermediate Water during the Younger Dryas. Paired records of benthic foraminiferal Mg/Ca and deltaO18 from two intermediate depth low latitude western Atlantic sites-one from the Florida Current (751m) and one from the Little Bahama Bank (1,057m)-provide insights into the spatial distribution of intermediate depth temperature and salinity variability during the Younger Dryas. The intermediate depth paleoceanographic temperature and salinity data are consistent with the results of a GFDL R30 freshwater forced model simulation, suggesting that freshwater forcing is a possible driver/amplifier of climate var.
Book Synopsis A ~3000 Year Multi-Proxy Paleoclimate Record from the Guaymas Basin, Gulf of California by : Zach Stewart
Download or read book A ~3000 Year Multi-Proxy Paleoclimate Record from the Guaymas Basin, Gulf of California written by Zach Stewart and published by . This book was released on 2017 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Guaymas Basin, Gulf of California, is an important site for paleoclimate study due to ideal preservation conditions and high sedimentation rates, which allow for high-resolution analysis of paleoclimate records and investigation of climatic and oceanographic processes that operate over timescales not resolved by modern instrumental records. Furthermore, the Guaymas Basin receives some water advected at depth from the Eastern Tropical North Pacific (ETNP), a region where oceanographic processes are closely coupled to the global climate system. The past climate and oceanography of the Gulf of California and ETNP have been well studied at low resolution over glacial-interglacial timescales: the goal of this study is to elucidate Mid- to Late Holocene oceanographic and climate changes at a higher resolution than previous studies in order to resolve decadal to centennial variance. Three main conclusions can be drawn from the new high-resolution records presented here. First, a careful comparison of radiocarbon dating and layer counting data calls into question the completeness of varved marine sequences in the Guaymas Basinches Second, stable isotopes, elemental composition data, XRF core scan trace metal counts, and smear slide analysis are used to identify a significant change in mean conditions and ecosystem structure at ~2800 yr BP, which is probably driven by southward displacement of the Inter-tropical Convergence Zone (ITCZ). Notably, mean bulk delta15N is ~0.6‰ lower after 2800 yr BP, suggesting decreased denitrification and improved ventilation. Third, important frequencies of variance at centennial and decadal periodicities are identified. Comparison of these new high-resolution proxy records to previous work in other regions suggests that Mid- to Late Holocene changes in the Guaymas Basin may be linked to climate changes across a larger spatial scale.
