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Late Holocene Climate Change On Isla Isabela Gulf Of California
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Book Synopsis Late Holocene Climate Change on Isla Isabela, Gulf of California by : Amy Englebrecht
Download or read book Late Holocene Climate Change on Isla Isabela, Gulf of California written by Amy Englebrecht and published by . This book was released on 2010 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediments from the crater lake on Isla Isabela, in the southern Gulf of California, were used to investigate precipitation and evaporation changes in this region over the past 6,000 years. Stable isotopes of oxygen and carbon provided a proxy record of Pacific climate variability on timescales ranging from decadal to millennial. Strength in the dominant periodicities of the Pacific Decadal Oscillation appears to have been intermittent over the past two millennia, suggesting changes in Pacific forcing not previously recognized. In addition, productivity in the lake varies on timescales that suggests a link between increased productivity and solar maxima. Although the precise role of solar activity on climate variations remains unclear, this data represents a convergence of model output with empirical evidence over the past millennium. Over the late Holocene, it appears that there have been a number of pronounced dry periods that generally coincide with cold sea surface temperatures in the eastern Pacific, and generally dry conditions across western North America.
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 Late Holocene Depositional History of Western Shelf Margin, Gulf of California, Mexico by : Kristi Anne Rikansrud
Download or read book Late Holocene Depositional History of Western Shelf Margin, Gulf of California, Mexico written by Kristi Anne Rikansrud and published by . This book was released on 1998 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Paleoenvironmental Change in Central California in the Late Pleistocene and Holocene by : Alicia Cowart
Download or read book Paleoenvironmental Change in Central California in the Late Pleistocene and Holocene written by Alicia Cowart and published by . This book was released on 2014 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dramatic environmental changes have occurred in the last 50,000 years in California due both to changes in climate and anthropogenic impacts. Analyses of pollen and microscopic charcoal from sediment cores from three wetland sites in central California record changes in vegetation and fire frequencies during the late Pleistocene and Holocene at different temporal resolutions. A long-term record with a basal date of ca. 50,000 cal yrs BP from a coastal wetland north of Santa Cruz shows important vegetation shifts between the Last Glacial Maximum, the glacial-interglacial transition, and the mid- to late-Holocene, as well as the introduction of a frequent fire regime in the Holocene. A 3,000-year record from a wetland near Año Nuevo State Park provides evidence of an increase in fire frequency in coastal California from the fifteenth century to the present, and vegetation changes associated with logging after Euro-American settlement. A core that spans the last ca. 700 years from an oxbow lake in the Sacramento Valley records the introduction of non-native plants into the area after European arrival. Together, these records help place the magnitude of anthropogenic impacts in the context of long-term environmental change due to regional or global climatic forcing.
Book Synopsis Contextualizing Late Holocene Subsistence Change on California’s Northern Channel Islands by :
Download or read book Contextualizing Late Holocene Subsistence Change on California’s Northern Channel Islands written by and published by . This book was released on 2018 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complex relationship between sociopolitical complexity, natural climatic change, and subsistence strategies on California’s Northern Channel Islands (NCI) has long been a topic of archaeological inquiry. One period of particular interest to NCI researchers is the Middle-to-Late Transition Period (MLT, 800-650 cal BP), during which Chumash hierarchical sociopolitical organization is thought to have solidified. Multiple models of sociopolitical change have been proposed, all of which acknowledge the relationship between rising populations, shifting dietary patterns, climatic events, and sociopolitical structure. Due to data gaps and the history of archaeological research on the Channel Islands, however, these models rely on dietary data from MLT and Late Period (650 cal BP to AD 1542) archaeological sites on Santa Cruz Island, but lack critical data from the Middle Period to contextualize subsistence shifts. Through my thesis research, I present and interpret dietary data from two well-dated Middle Period sites on Santa Cruz Island through a historical ecological framework to place dietary shifts in spatial and temporal context and to aid in a deeper understanding of Chumash lifeways during a very dynamic time on the NCI.
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 Changing Subsistence Patterns in the Late Holocene, on Isla Cedros, Baja, California by : Deborah V. Roman
Download or read book Changing Subsistence Patterns in the Late Holocene, on Isla Cedros, Baja, California written by Deborah V. Roman and published by . This book was released on 2010 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene Climate Fluctuations and Culture Change in Southeastern North America by : Keith J. Little
Download or read book Late Holocene Climate Fluctuations and Culture Change in Southeastern North America written by Keith J. Little and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Holocene Sedimentation in the Southern Gulf of California and Its Climatic Implications by : Oscar Efraín González-Yajimovich
Download or read book Holocene Sedimentation in the Southern Gulf of California and Its Climatic Implications written by Oscar Efraín González-Yajimovich and published by . This book was released on 2004 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene climate and cultural changes in the southwestern United States by : Victor J. Polyak
Download or read book Late Holocene climate and cultural changes in the southwestern United States written by Victor J. Polyak and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Holocene Climate and Environmental Change Inferred from Arctic Lake Sediment by : Darrell S. Kaufman
Download or read book Late Holocene Climate and Environmental Change Inferred from Arctic Lake Sediment written by Darrell S. Kaufman and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Book Synopsis Late holocene climate in the North Atlantic and the role of the Thermohaline Circulation System on climate change by : Helen Farhall
Download or read book Late holocene climate in the North Atlantic and the role of the Thermohaline Circulation System on climate change written by Helen Farhall and published by . This book was released on 2008 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Holocene Climate Change and Human Environmental Impacts in Guanajuato, Mexico by : Jungjae Park
Download or read book Holocene Climate Change and Human Environmental Impacts in Guanajuato, Mexico written by Jungjae Park and published by . This book was released on 2005 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Late Pleistocene and Holocene Climate Change in the Maya Lowlands by : Jaime Escobar
Download or read book Late Pleistocene and Holocene Climate Change in the Maya Lowlands written by Jaime Escobar and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Individual [lowercase delta]18O measurements on C. ilosvayi in sediments from Lake Punta Laguna show that samples from core depths that have high mean [lowercase delta]18O values, indicative of low effective moisture, display lower variability, whereas samples with low mean [lowercase delta]18O values, reflecting times of higher effective moisture, display higher variability. Relatively dry periods were thus consistently dry, whereas relatively wet periods had both wet and dry years. This interpretation of data from the cores applies to an important period of the late Holocene, the Maya Terminal Classic. [Lowercase delta]18O variability during the ancient Maya Terminal Classic Period (ca. 910-990 AD) indicates not only the driest mean conditions in the last 3,000 years, but consistently dry climate. Variability of [lowercase delta]13C measurements in single stratigraphic layers displayed no relationship with climate conditions inferred from [lowercase delta]18O measurements.
Book Synopsis Late Holocene Relative Sea-level Changes, Arcata Bay, California by : Chad James Pritchard
Download or read book Late Holocene Relative Sea-level Changes, Arcata Bay, California written by Chad James Pritchard and published by . This book was released on 2004 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reconstructing Late Holocene Artctic Climate Change Using High Resolution Sediment Records from Simpson Lagoon, Alaska and the Colville River Alluvial Valley by : Andrea Jo Miller Hanna
Download or read book Reconstructing Late Holocene Artctic Climate Change Using High Resolution Sediment Records from Simpson Lagoon, Alaska and the Colville River Alluvial Valley written by Andrea Jo Miller Hanna and published by . This book was released on 2015 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic nearshore environments proximal to large rivers, like Simpson Lagoon, Alaska, potentially contain high-resolution sediment archives that can be utilized to reconstruct paleoclimate variability over the late Holocene. The ongoing, rapid environmental changes recently observed in the Arctic highlight the need for high-resolution records of pre-industrial climate change in this climatically sensitive region; such records are fundamental for understanding recent anthropogenic changes in the context of natural variability. This dissertation utilizes a suite of geochemical and sedimentological proxies in combination with age-constrained, shallow acoustic reflection data to demonstrate that these underutilized coastal sediment archives are capable of generating high-resolution paleoclimate records on par with other terrestrial climate archives (i.e. lake sediments, ice cores, tree rings) and provides the first ~1650-year long record of climate variability from the inner shelf of the Alaskan Beaufort Sea. An analysis of sedimentation patterns within Simpson Lagoon using CHIRP seismic data and radioisotope geochronology reveals that sediment infilling in Simpson Lagoon began ~3500 y BP, creating a primary depocenter with mm y−1 sediment accumulation in western Simpson Lagoon. The interbedded sediments suggest that major sediment reworking from ice processes, a common occurrence in Arctic shelf environments, does not disrupt the sediment archive contained within the lagoon. Quantitative reconstructions of surface air temperature are obtained using the brGDGT-derived MBT'/CBT paleothermometer. A comprehensive study of lagoon and river sediments and catchment soils demonstrate that brGDGTs are primarily soil-derived, and yield reconstructed temperatures consistent with instrumental summer temperature observations from Alaska's North Slope. Temperature reconstructions from Simpson Lagoon also show similarities with regional and pan-Arctic climate records over the last few millennia, with evidence of temperature departures correlative with noted climate events (i.e., Little Ice Age, Medieval Climate Anomaly). In addition, temporal variability in sediment sourcing to the lagoon, determined using a multi-proxy approach (i.e., granulometry, elemental analysis, clay mineralogy), broadly corresponds with temperature fluctuations, indicating relative increases in fluvial sediment discharge during colder intervals and decreased river discharge/increased coastal erosion during warmer periods. This paleoclimate variability may be driven by variations in solar output and/or shifts in the regional ocean-atmosphere circulation patterns (e.g., the Aleutian Low).
