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 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 Ocean Temperature Variability During the Late Pleistocene written by Jeremy Scott Hoffman and published by . This book was released on 2016 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation explores one overarching question relevant to the paleoclimate of the latest Pleistocene glacial cycle (approximately the last 130,000 years): “How did spatial and temporal evolution of ocean temperature, both at the surface and interior, relate to other parts of the climate system in the late Pleistocene?” Results from three studies are presented that seek to address longstanding questions in paleoceanography and paleoclimatology for the late Pleistocene using a combination of novel and accepted statistical and geochemical analysis techniques and leveraging comparisons with available global climate model data. The last interglaciation (LIG; ~129-116 ka) was the most recent period in Earth’s history with higher-than-present global sea level (≥6-9 m) under similar-to-preindustrial concentrations of atmospheric CO2. This suggests that additional feedbacks related to albedo, insolation, and ocean overturning circulation may have resulted in the apparent warming required to cause the higher sea level. Our understanding of how much warmer the LIG was relative to the present interglaciation remains uncertain, however, with current estimates suggesting that sea-surface temperatures (SSTs) were 0-2°C warmer than late-20th century average global temperatures. We present a global compilation of proxy-based annual SST spanning the LIG. Using Monte Carlo and Bayesian techniques to propagate uncertainties in age-model and proxy-based SST reconstructions, our results quantify the spatial timing, amplitude, and uncertainty in global and regional SST change during the LIG. Our conclusions suggest that the LIG surface ocean was indistinguishable from the average surface ocean temperatures observed for the last two decades (1995-2014). This may ultimately imply that the Earth is currently committed to ≥6-9m of equilibrium sea-level rise. Although the LIG is not an analogue for present and future climate change due to the large differences in seasonal orbital insolation and absence of anthropogenic greenhouse gas radiative forcing, it provides an opportunity to test the ability of global climate models to simulate the mechanisms and climate feedbacks responsible for the warmer climate and higher global mean sea level during the LIG. However, when forced only by LIG greenhouse gas concentrations and insolation changes, climate models suggest that the annual mean temperature response was not significantly different from preindustrial control simulations. We present the first multi-model and multiscenario ensemble of transient and equilibrium global climate modeling results spanning the LIG. We show, using a novel model-data comparison framework, that these scenario-specific model results exhibit regionally independent agreement with ocean basin-specific proxy-based SST stacks. This result ultimately implies structural uncertainties and/or misrepresentations of climate feedbacks in the existing suite of climate model simulations, or underestimations of additional proxy-based SST uncertainties. Our conclusions suggest a new target LIG time period for future model-data comparisons and highlight the need for higher resolution transient climate modeling of the LIG and its dependence on meltwater input to the high latitude oceans during the preceding deglaciation. Few discoveries have stimulated the paleoclimate community more so than Heinrich events. Nevertheless, the cause of Heinrich events, characterized by a large flux of icebergs sourced from the Hudson Strait Ice Stream into the North Atlantic, remains debated. Commonly attributed to internal ice-sheet instability, the occurrence of Heinrich events during the coldest intervals of the last glacial cycle instead suggests an external climate control. We expand on recent studies that have shown that incursions of warm subsurface waters into the intermediate depth North Atlantic Ocean destabilized an ice shelf fronting the Hudson Strait Ice Stream, causing a Heinrich event. We present new surface- and bottom-water stable isotope, trace metal, and sedimentary records from two cores taken along the Labrador margin that further support subsurface warming as a trigger of Hudson Strait Heinrich events. We further relate these changes to other sediment core records from the North Atlantic and transient deglacial climate modeling results to show that subsurface warming was ubiquitous across the intermediate North Atlantic during the early part of the last deglaciation and was most likely caused by a preceding reduction in the Atlantic Meridional Overturning Circulation.
Download or read book Encyclopedia of Quaternary Science written by Cary Mock and published by Newnes. This book was released on 2013-03-25 with total page 3883 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second revised edition of the Encyclopedia of Quaternary Science, Four Volume Set, provides both students and professionals with an up-to-date reference work on this important and highly varied area of research. There are lots of new articles, and many of the articles that appeared in the first edition have been updated to reflect advances in knowledge since 2006, when the original articles were written. The second edition will contain about 375 articles, written by leading experts around the world. This major reference work is richly illustrated with more than 3,000 illustrations, most of them in colour. Research in the Quaternary sciences has advanced greatly in the last 10 years, especially since topics like global climate change, geologic hazards and soil erosion were put high on the political agenda. This second edition builds upon its award-winning predecessor to provide the reader assured quality along with essential updated coverage Contains 357 broad-ranging articles (4310 pages) written at a level that allows undergraduate students to understand the material, while providing active researchers with a ready reference resource for information in the field. Facilitates teaching and learning The first edition was regarded by many as the most significant single overview of Quaternary science ever, yet Editor-in-Chief, Scott Elias, has managed to surpass that in this second edition by securing even more expert reviews whilst retaining his renowned editorial consistency that enables readers to navigates seamlessly from one unfamiliar topic to the next
Download or read book Paleoclimates written by Thomas M. Cronin and published by Columbia University Press. This book was released on 2010 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: "When combined with computer model simulations, paleoclimatic reconstructions are used to test hypotheses about the causes of climatic change, such as greenhouse gases, solar variability, earth's orbital variations, and hydrological, oceanic, and tectonic processes, This book is a comprehensive, state-of-the art synthesis of paleoclimate research covering all geological timescales, emphasizing topics that shed light on modern trends in the earth's climate." --Book Jacket.
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 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 Salinity and Temperature Variability in the Caribbean and the North Atlantic Gyre During the Last Three Ice Age Cycles on Millennial and Orbital Time Scales written by Matthew William Schmidt and published by . This book was released on 2005 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spring Meeting written by American Geophysical Union. Meeting and published by . This book was released on 2001 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Late Pliocene to Early Pleistocene Millennial scale Climate Fluctuations and Sea level Variability written by Kim Jakob and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Tropical North Atlantic Hydrologic Cycle Variability in the Florida Straits During the Last Ice Age written by Theodore Them and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abrupt, millennial-scale climate oscillations, known as Dansgaard-Oeschger (D-O) cycles, characterized the climate system during the last ice age. Proxy evidence suggests these climate oscillations resulted in global-scale reorganizations in the hydrological cycle. For this study, Mg/Ca-paleothermometry and stable isotope measurements were combined on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC26 (24*19.61'N, 83*15.14'W; 546 m depth) to reconstruct a high-resolution record of sea surface temperature and delta18OSW (a proxy for upper water column salinity) during Marine Isotope Stages 2 and 3 from 20-35.45 ka BP. As additional proxies for upper water column salinity change, Ba/Ca ratios in G. ruber were also measured to determine the relative contribution of local riverine input on the delta18OSW record and a faunal abundance count record of the planktonic foraminifera N. dutertrei abundance was developed. These results show that rapid upper water column salinity changes occurred across D-O events in the Florida Straits, coeval with climate change in the high-latitude North Atlantic. Furthermore, the G. ruber Ba/Ca record suggests that riverine-derived meltwater from the Gulf of Mexico did not significantly impact surface salinity in the Florida current, calling into question the role of Mississippi River discharge on Atlantic Meridional Overturning Circulation (AMOC) during MIS 2 and 3. Instead, the most likely cause of MIS 2 and 3 salinity changes in the Florida Straits were variations in the strength and position of the Intertropical Convergence Zone. Finally, the timing of surface salinity change was compared with the benthic delta18OC record from the same core. A recent study showed that benthic delta18OC changes on the Florida Margin can be combined with contemporaneous records from the Bahamas Margin to reconstruct Florida Current transport related to AMOC variability. These results show that atmospheric circulation changes lead AMOC changes on the transition out of cold stadial events, suggesting the trigger for these abrupt climate events may reside in the tropics rather than in the high-latitude North Atlantic as previously thought.
Download or read book Gulf of Mexico Its Origin Waters and Marine Life written by Paul Simon Galtsoff and published by . This book was released on 1954 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Late Pleistocene to Holocene Changes in Upper ocean Stratification and Its Impact on Marine Productivity Sea Surface Temperatures and Salinity in the Subarctic Northwest Pacific written by Jan-Rainer Riethdorf and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Millennial scale Variability During the Pleistocene written by Carolyn F. Lindley and published by . This book was released on 2004 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AGU 2004 Joint Assembly written by American Geophysical Union. Joint Assembly and published by . This book was released on 2004 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
