Other Earth Sciences Commons^™

The Upper Ocean At The End Of An Ice Age: Using Proxies In Benthic Foraminifera To Investigate Intermediate Water Changes During The Last Glacial Termination, Cassandre R. Stirpe

Electronic Theses and Dissertations

The ocean is an important component of the global climate system and plays a key role as a storage reservoir for heat and carbon. Under glacial conditions, the ocean sequestered carbon from the atmosphere, contributing to a cooler global climate. During the last glacial termination, that carbon was released back into the atmosphere, but the exact timing and mechanisms of this transfer are still not fully understood. This study examines waters from the intermediate depths of the Southern Ocean to gain insight into deglacial processes. Intermediate waters are capable of reacting to climate change on decadal timescales, making them a …

Investigation Of Cryptotephra In Polar Ice Cores, Meredith Helmick

Electronic Theses and Dissertations

Volcanic ash (tephra) present within polar ice cores greatly supplements our understanding of past volcanism and its impacts on society and the state of the climate system. This thesis investigates the utility and limitations of ice core tephrochronology in answering questions related to volcanic source identification of ice core glaciochemical signals, tephrostratigraphy of an Antarctic ice core, and the timing of major and climate forcing eruptions. This thesis explores the efficacy of SEM-EDS measurements on ultra-fine (µm) volcanic particles for the purpose of geochemically characterizing a non-visible ice-embedded tephra and the subsequent identification of the volcanic source. In combination with …

Glaciochemical Investigations In Three Southern Hemisphere Mountain Sites, Mariusz Potocki

Electronic Theses and Dissertations

The research presented in this dissertation focuses on glaciochemical records of trace elements, major ions, and stable water isotopes from three mountain regions: the Antarctic Peninsula, the Central Chilean Andes, and South Georgia Island.

The first section reports a significant increase in U concentration over 27 years on Detroit Plateau, Antarctic Peninsula. U concentrations in the ice core increase by as much as 102 between the 1980s and 2000s, accompanied by increased variability in recent years. The U concentration increase coincides with expanded open pit mining in the Southern Hemisphere, most notably Australia. Since other land-source dust elements do not …

Examining Summertime Melt And Temperatures In The North Pacific Cordillera, Ingalise Kindstedt

Electronic Theses and Dissertations

Temperature changes in glaciated regions are of immediate concern for estimates of future sea level rise. Alaska and the surrounding region contain over 40 mm of potential sea level rise in its many alpine glaciers, which are experiencing some of the highest rates of mass loss globally. However, records of both past and present temperatures in the region’s alpine sectors are sparse and limited in temporal and spatial extent. Here I examine the application of MODIS land surface temperatures and layers of refrozen melt in ice cores as temperature indicators in the St. Elias and Alaska Ranges. First, I find …

Sulfur And Trace Metal Cycling At Convergent Margins, Jesse B. Walters

Electronic Theses and Dissertations

Subduction zones are the site of long-term chemical exchange between Earth’s surface and interior geochemical reservoirs. Subducting slabs are progressively depleted in volatiles and other mobile elements through dehydration and melting reactions. These elements are then introduced to the mantle wedge and volcanic arc. One consequence of this cycle is that volcanic arcs produce the most oxidized magmas on Earth. Sulfur, which exhibits a range in valence states from S^2- to S⁶⁺, is one of the few elements in the subducting slab capable of oxidizing the arc and mantle wedge. Sulfides in the slab may also act …

Fostering Climate Change Resilience: A Socio-Ecological Forest Systems Approach, Alyssa R. Soucy

Electronic Theses and Dissertations

As climate change continues to impact socio-ecological systems, those that rely on natural resources are highly sensitive to climatic changes. Maine’s forest industry provides for the economic and social well-being of many residents and is especially vulnerable to climate change impacts. Changes in growing season length and timing, forest health threats imposed by insects and pathogens, extreme weather events, shifting forest composition, and changes in natural disturbance severity and frequency have already begun, and are projected to continue, to impact forest systems in the Northeastern U.S. While climate change presents a threat to forest systems, opportunities also arise due to …

Past, Present, And Future Arctic Climate And National/Community Risk Assessment, Jeff Auger

Electronic Theses and Dissertations

The Arctic is warming at a rate nearly double that of the global average. The enhanced rate of warming impacts weather and climate across the Northern Hemisphere. As the meridional (south to north) thermal gradient weakens, the middle-latitude westerlies are expected to slow and become “wavier” increasing heat and moisture advection to higher latitudes. A quasi-stationary ridge-trough system of the jet stream increases chances for droughts, floods, heatwaves, and cold spells. These impacts have already been observed as North American forest fires and early or extended Great Lake ice out. It is more important than ever to understand how the …

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

Assessing The Reliability Of The Benthic Mg/Ca–Temperature Proxy: A Uvigerina Core-Top Study From New Zealand, Cassandre R. Stirpe

Electronic Theses and Dissertations

Sediment cores from New Zealand’s Bay of Plenty and the Chatham Rise in the Southwest Pacific were sampled to establish a regional Mg/Ca–temperature calibration for the benthic foraminifer Uvigerina peregrina. Comparison of foraminiferal Mg/Ca from core-top sediments to local bottom water temperatures reveals a Mg/Ca–temperature relationship broadly consistent with previously published calibrations. In addition to bottom water temperatures, other environmental parameters are examined for possible influence on the Mg/Ca of foraminiferal calcite. Elderfield et al. (2006) proposed that such parameters may exert an influence at colder temperatures, particularly below temperatures of ~3oC (e.g. Lear et al., 2002; Elderfield et al., …

Late Holocene Climate And Environmental Reconstruction Derived From The Asian Ice Core Array (Aica), Bjorn Grigholm

Electronic Theses and Dissertations

Recent climate change has impacted natural and human systems across the Earth, emphasizing the need for greater understanding of both the existing and changing natural and anthropogenic forcing mechanisms and subsequent responses of the Earth’s climate system. High-resolution, multi-parameter ice core records retrieved and analyzed from two Asian Ice Core Array (AICA) sites, Geladaindong (central Tibetan Plateau) and Inilchek (central Tien Shan) were utilized to reconstruct atmospheric chemical concentrations and composition over the past ~100-500 years, improving the understanding of late Holocene climate and environmental variability in Asia. Both ice cores were analyzed for major and trace elements, major soluble …

Historical Floods In New England, M. T. Thomson, William B. Gannon, M. P. Thomas, G. S. Hayes

Maine History Documents

One or more of the great recent New England floods of 1927, 1936, 1938, and 1955 exceeded the greatest known historical floods on most of the major rivers. Locally, on tributary streams, the great floods of recent years probably exceeded historical floods, but the certainty diminishes for the floods that occurred prior to the observance of living witnesses.

This report presents, by year, a condensation of the data on unusual historical floods (floods that occurred before establishment of gaging stations) and the sources of this evidence. This information will be helpful in the determination of the frequency of the highest …