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Holocene Climate Variability In Tropical South America Case History From A High Mountain Wet Zone In Nw Colombia Based On Palynology And X Ray Microfluorescence
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Book Synopsis Holocene climate variability in tropical South America : case history from a high-mountain wet zone in NW Colombia based on palynology and X-ray microfluorescence by : Paula Andrea Muñoz Uribe
Download or read book Holocene climate variability in tropical South America : case history from a high-mountain wet zone in NW Colombia based on palynology and X-ray microfluorescence written by Paula Andrea Muñoz Uribe and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A 1,500-year Record of Late Holocene Temperature Variability and Recent Warming from Laguna Chingaza, Colombia by : Curtis William Bixler
Download or read book A 1,500-year Record of Late Holocene Temperature Variability and Recent Warming from Laguna Chingaza, Colombia written by Curtis William Bixler and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid tropical glacier retreat over the last 50 years has been well documented, and has received significant media attention. Many studies suggest these changes are due to rising global surface air temperatures, however disentangling the effects of temperature and precipitation has hampered scientific consensus. Furthermore, because of the shortness of the instrumental record, it is difficult to assess the larger significance of the climate changes associated with the decline of tropical glaciers. Here, we present a locally calibrated, independent temperature reconstruction for the past 1,500 years from Laguna Chingaza, Colombia based on distributions of branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) in order to assess the controls on long term temperature variability in the tropical Andes, and their relationship with growth and demise of Andean glaciers. Comparison of reconstructed temperatures with the instrumental record suggests that our proxy record faithfully records decadal to century scale trends in temperature. The largest temperature decline over the last 1,500 years was a decrease of 2.5 ± 0.3 °C during the Little Ice Age (LIA), reaching lowest temperatures during the mid-17th century, and is broadly consistent with terrestrial temperature reconstructions throughout the tropics and the higher latitudes. The structure and timing of temperature changes at Laguna Chingaza are remarkably similar to recent terrestrial temperature reconstructions from elsewhere in the tropics, including sites in the tropical Pacific and equatorial Africa, suggesting that these changes are widespread in the tropics. Together, these records suggest that warming over the last few decades is unprecedented over the last 1,500 years, including the Medieval Climate Anomaly (800-1150 AD). Comparison of these temperature changes with records of Andean glacier limits suggests that temperature is the dominant driver of glacial retreat, particularly over the past few decades. Additionally, paleotemperatures inferred from LIA and recent glacial equilibrium line altitudes (ELAs) underestimate past changes in temperature when compared with brGDGTs reconstructions, suggesting that changes in precipitation complicate the use of glacier ELAs to reconstruct past temperatures. The coupling of temperature and ice extent in South America suggests that with projected future warming, the health of tropical glaciers could be in jeopardy, significantly impacting the communities and ecosystems that depend on them.
Book Synopsis Holocene Climate Fluctuations in Tropical South America Deduced from an Illimani Ice Core by : Thomas Kellerhals
Download or read book Holocene Climate Fluctuations in Tropical South America Deduced from an Illimani Ice Core written by Thomas Kellerhals and published by . This book was released on 2008 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Climatic Change During the Late Glacial Northwestern Part of Colombia, Based on Palynology and Microfluorescence-x by : Carlos Albeiro Monsalve Marin
Download or read book Climatic Change During the Late Glacial Northwestern Part of Colombia, Based on Palynology and Microfluorescence-x written by Carlos Albeiro Monsalve Marin and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Pliocene-Pleistocene Evolution of Flora, Vegetation and Climate by : Vladimir Torres Torres
Download or read book Pliocene-Pleistocene Evolution of Flora, Vegetation and Climate written by Vladimir Torres Torres and published by . This book was released on 2006 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The sediments from the basin of Bogotá (4°N, 74°W, 2550 m altitude) constitute one of the best investigated archives in terms of basin development, vegetation history, and climate change during the Quaternary (Pleistocene). Long sediment cores, drilled up to the bedrock of the basin, have provided the materials for study. In this thesis the results of the longest high resolution pollen record yet are presented: the record has a high resolution of ca. 1500 years for the last 3.2 million years. The body of this research shows the geological development of the basin, sediment infill and the development of different depositional environments, the evolution of the regional flora including several immigraiton events of important taxa, the history of vegetation change which is representative of the northern Andes, and the inferred record of climate change and climate variability. For the first time: 1) the complete sequence of ice ages is documented in a terrestrial record, and 2) the evolution of North Andean biomes has been placed in ccontinuouslychanging physical (abiotic) context." -- P.V.
Book Synopsis Holocene Climatic History of South America by : V. Markgraf
Download or read book Holocene Climatic History of South America written by V. Markgraf and published by . This book was released on 1982 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene Climate Variability in the Southwestern United States from High-resolution Speleothem Data by : Jessica Belle Toledo Rasmussen
Download or read book Late Holocene Climate Variability in the Southwestern United States from High-resolution Speleothem Data written by Jessica Belle Toledo Rasmussen and published by . This book was released on 2006 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Abrupt Holocene Climate Change by : Aron Maurice Buffen
Download or read book Abrupt Holocene Climate Change written by Aron Maurice Buffen and published by . This book was released on 2008 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Three ice cores drilled to bedrock atop Nevado Coropuna, southwestern Peru reflect Holocene and late glacial stage climate variability. Two cores measure 34 m in length yet provide seemingly continuous16 kyr histories, and thus represent the shortest known ice cores to extend from the present into the last glacial. High major ion concentrations and dust particle diameter ratios identify a succession of abrupt and severe Holocene droughts on the Altiplano centered at 3.4, 4.2, 5.6, 7.5, 8.2 and 10.1 kyr B.P. Modern precipitation availability in the region is dominated by ENSO variability on interannual timescales and these events may thus reflect extended periods of El Niño-like conditions in the tropical Pacific. The Deglaciation Climate Reversal, the tropical counterpart to the Northern Hemisphere Younger Dryas stadial, is marked by large, abrupt stable isotopic depletion, with [delta]18O ~9-10 per mil lower at this time relative to the early Holocene. This [delta]18O shift is remarkable as it is ~4-5 per mil greater than that observed in any previously drilled central Andean ice core record. In concert with marked, synchronous deuterium-excess increases, these shifts may be explained by a coeval southward migration of the ITCZ. Decreased major ion and dust concentrations and low dust particle diameter ratios likely reflect increased central Andean precipitation at this time, in agreement with other regional paleoclimate records. A complete history could not be produced for the third core due to conflicting dating results. Annual resolution over the past 244 years allows for a detailed assessment of recent regional climate change and its relation to possible forcings. Decadal [delta]18O variability is strongly correlated with tropical Pacific sea surface temperatures and lends support to precipitation, via the amount effect, controlling [delta]18O on these timescales. On longer timescales, temperature plays an increasingly important role in governing this parameter and it is suggested that 20th century [delta]18O enrichment is influenced by recent tropospheric warming resulting from anthropogenic greenhouse gas emissions. Radiocarbon dating of well preserved, in-place vegetation exposed by the retreating Quelccaya Ice Cap, southeastern Peru constrains the last time the ice cap's extent was smaller than at present. Seventeen plant samples from two sites along the central western margin collectively date to 4.7 and 5.1 kyr B.P. and strongly indicate that current ice cap retreat is unprecedented over the past ~5 millennia. Seventeen vegetation samples interbedded in a nearby clastic sedimentary sequence suggest ice-free conditions at this site from ~5.2 to at least ~7 kyr B.P., and place minimum constraint on early- to mid-Holocene ice cap extent. A growing body of globally distributed, independently dated paleoclimate records collectively identifies a series of contemporaneous abrupt climate change events during the Holocene that are generally coeval with reductions in solar output. A mechanistic hypothesis for these events, involving the tropical Pacific shifting to an El Niño-like mean state via a non-linear response of the coupled ocean-atmosphere system to reduced radiative heating, is discussed. Support for this explanation utilizing the abrupt drought events captured in the CRC1 record is equivocal.
Book Synopsis Climatic Change During the Late Glacial in the Northwestern Part of Colombia, Bases on Palynology and Microfluorescence-X by : Carlos Albeiro Marín Monsalve
Download or read book Climatic Change During the Late Glacial in the Northwestern Part of Colombia, Bases on Palynology and Microfluorescence-X written by Carlos Albeiro Marín Monsalve and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis From Saline to Freshwater by : Scott W. Starratt
Download or read book From Saline to Freshwater written by Scott W. Starratt and published by Geological Society of America. This book was released on 2021-12-23 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A 4600-year Record of Lake Level and Local Hydroclimate Variability from an Eastern Andean Lake in Colombia by : Owen M. Rudloff
Download or read book A 4600-year Record of Lake Level and Local Hydroclimate Variability from an Eastern Andean Lake in Colombia written by Owen M. Rudloff and published by . This book was released on 2016 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydroclimatic variability in the eastern Colombian Andes is examined using a decadally-resolved, multiproxy lake sediment record from Laguna de Ubaque, Colombia. Hydroclimate trends are examined and compared to existing local, regional, and trans-Andean records to enhance existing knowledge of Late Holocene Colombian precipitation and assess potential hydroclimatic forcing mechanisms in tropical South America. Sedimentological analyses, including percent lithics, grain size, C:N and magnetic susceptibility are sensitive to hydroclimate and lake level while charcoal size and concentrations reflect fire variability. Results show that deep lacustrine conditions characterized by laminated deposits were not established until approximately 3500 cal yr B.P., prior to which, terrestrial C:N values and unstructured sediments indicate that drier, marsh-like conditions prevailed. Between 3500 and 2000 cal yr B.P., interrupted only by a 300-year arid interval from 2800 to 2500 cal yr B.P., greatly increased overall clastic deposition indicates a broad precipitation maximum while decreased sand deposition and the preservation of finely laminated sediment indicate deep lake conditions. After 2000 cal yr B.P., decreased clastic deposition suggests reduced precipitation, but the continued accumulation of laminated sediments indicates that conditions were wet enough to fill the basin continuously until the present day. These observations address two of the driving questions of Andean paleoclimate: were the northern and southern Andes in vi phase during the Holocene, or out of phase, and what are the main drivers of Holocene Andean climate? We find that the early part of Ubaque’s record more closely resembles southern Andean precipitation records until 2000 cal yr B.P., at which point it abruptly switches to resemble northern precipitation records. We attribute this to a combination of the southward migration of the intertropical convergence zone (ITCZ), and an increase in eastern Pacific sea surface temperatures (SST). In addition, we find that Colombian hydroclimate records exhibit a bimodal precipitation pattern, which we attribute to their location either on the Andean slopes or in the high interior Andes.
Book Synopsis Late Holocene Oxygen Isotope Record of Hydroclimate Variability in Nicaragua from Lake Asososca by : Stephen Perdziola
Download or read book Late Holocene Oxygen Isotope Record of Hydroclimate Variability in Nicaragua from Lake Asososca written by Stephen Perdziola and published by . This book was released on 2018 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of hydroclimate requires a higher level of spatial and temporal detail than what currently exists for Central America. High resolution lake sediment archives are critical to gaining a more complete understanding of late Holocene climate variability in the region. The climate of Central America is influenced by both tropical Atlantic and Pacific Ocean-atmosphere processes. A better understanding of how these processes have impacted regional hydroclimate is important as it will enable more accurate predictions of future climate changes associated with shifting conditions in a drought sensitive region. Here a 1,000-year carbonate oxygen isotope record is presented from Lake Asososca, located in western Nicaragua. In this record, high delta 18O values indicate drier conditions, while lower ?18O values indicate drier conditions. My data indicate wet conditions at the start of the Medieval Climate Anomaly (MCA) and a trend towards drier conditions until A.D. 1200. The transitional period between the MCA and the Little Ice Age (LIA) from A.D. 1200 - 1400 experienced a shift towards wetter conditions. The LIA from A.D. 1400 -- 1850 was a period of variable conditions. My record indicates a shift from wet to dry conditions from A.D. 1400 - 1600. A pronounced period of wetter conditions occurred from A.D. 1650-1700 during the Maunder Minimum solar event. From A.D 1700 -- 1800 the record indicates variable conditions that alternated between shifts towards dry and wet. After the LIA, the record indicates a trend towards drier conditions. The El Nino Southern Oscillation (ENSO), the North American Oscillation (NAO), and the Atlantic Multidecadal Oscillation (AMO), were often temporally correlated with the Lake Asososca record and suggest that these modes have impacted regional hydroclimate over the late Holocene. Correspondence between the Lake Asososca record and solar variability highlight a potential linkage. Climate models indicate that the Atlantic Meridional Overturning Circulation responds to changes in solar variability and can have impacts on Atlantic SSTs, and therefore may be provide a mechanism to amplify changes in solar variability to Central American hydroclimate. Comparison of the Lake Asososca delta18O record to regional hydroclimate proxies across show little correspondence over the past millennium. While some similarities exist between the Lake Asososca record and other regional proxies, the lack of a coherent hydroclimate signal over the late Holocene suggests temporally and spatially variability hydroclimate shifts. More hydroclimate reconstructions and modelling studies need to be performed in order to fully resolve hydroclimate variability in Central America over the past millennium. This record adds to the network of regional paleoclimate reconstructions in Central America and indicates that modes of variability in both the Atlantic and Pacific Ocean basins have impacted regional hydroclimate over the past millennium.
Book Synopsis Late Holocene Climate Variability in the North Atlantic Based on Biomarker Reconstruction by : María Jesús Rubio de Inglés
Download or read book Late Holocene Climate Variability in the North Atlantic Based on Biomarker Reconstruction written by María Jesús Rubio de Inglés and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Climate Change in Lowland Central America During the Late Deglacial and Early Holocene by :
Download or read book Climate Change in Lowland Central America During the Late Deglacial and Early Holocene written by and published by . This book was released on 2005 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition ((almost equal to)11,250 to 7,500 cal yr BP) inferred from sediment cores retrieved in Lake Peten Itza, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by (almost equal to)11,250 cal yr BP, but sediment properties indicate that lake level was more than 35 m below modern stage. From 11,250 to 10,350 cal yr BP, during the Preboreal period, lithologic changes in sediments from deep-water cores (>50 m below modern water level) indicate several wet-dry cycles that suggest distinct changes in effective moisture. Four dry events (designated PBE1-4) occurred at 11,200, 10,900, 10,700, and 10,400 cal yr BP and correlate with similar variability observed in the Cariaco Basin titanium record and glacial meltwater pulses into the Gulf of Mexico. After 10,350 cal yr BP, multiple sediment proxies suggest a shift to a more persistently moist early Holocene climate. Comparison of results from Lake Peten Itza with other records from the circum-Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period appears to be tightly linked to climate change in the high-latitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores-Bermuda high-pressure system. This mechanism operated on millennial-to-submillennial timescales and may have responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and the Atlantic meridional overturning circulation (MOC).
Book Synopsis High-resolution Reconstruction of Glacial to Holocene Climate Variability from Sediments of the Cariaco Basin and Arabian Sea by : Gaudenz Deplazes
Download or read book High-resolution Reconstruction of Glacial to Holocene Climate Variability from Sediments of the Cariaco Basin and Arabian Sea written by Gaudenz Deplazes and published by . This book was released on 2012 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Holocene Caribbean Climate Variability Reconstructed from Speleothems from Western Cuba by : Claudia Fensterer
Download or read book Holocene Caribbean Climate Variability Reconstructed from Speleothems from Western Cuba written by Claudia Fensterer and published by . This book was released on 2011 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
