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Global sea-level rise contributed by Antarctic ice-mass loss could soon outpace all other sources. The ice-mass-loss signal of the Antarctic Ice Sheet is dominated by the Amundsen Sea Embayment (ASE) in West Antarctica. Ice shelves in the ASE influence the ice-mass-loss rates of the Antarctic Ice Sheet through their ability to buttress the grounded ice and modulate ice-flow speed. Ice shelves reduce ice flow and retreat by buttressing grounded ice. Previous studies show that sea ice can buttress ice shelves via mechanical bonding and provide protection from ocean swells. Whereas several studies have examined the trends in West Antarctic sea ice and dynamics of ice shelves in the ASE separately, the interaction between ice shelves and sea ice in the ASE is poorly understood. This study investigated the relationship between sea-ice-area (SIA) anomalies and ice-shelf velocities of three large ASE ice shelves, of Thwaites Eastern Ice Shelf (TEIS), Pine Island Glacier Ice Shelf (PIGIS) and Crosson Ice Shelf (CIS), on seasonal and monthly timescales from summer 2001-02 to 2021-22 and 2014 to 2022, respectively. SIA anomalies and ice-shelf velocities were derived from satellite remote sensing data. Sea ice in the ASE experienced four- to seven-year periods of relatively consistent positive or negative SIA anomalies. Time series of TEIS average velocity shows increased velocity in the early 2000's, followed by relative stability, then again an increase from the late-2010's onwards. Time series of the PIGIS average velocity shows increased velocities over the 20-year period, with consistent acceleration from the late-2010's onwards. Time series of the CIS average velocity shows relatively stable to slightly decreasing trends over the 20-year period. Correlation analysis of sea ice and ice shelves predominantly showed no significant relationship. Fewer than 15% of Spearman's correlation coefficients between the SIA anomalies and ice-shelf velocities were statistically significant. Therefore, results of this study indicate no apparent relationship between sea ice and ice-shelf velocity in the ASE, at least on seasonal and monthly time scales. The relationship may be more evident on an episodic basis than in a long-term record, as previous studies identified the influence of sea-ice events (i.e., sea-ice breakout or retreat) on Antarctic ice shelves on daily to weekly time scales.
Recent work has documented dramatic changes in the West Antarctic Ice Sheet (WAIS) over the past 30 years (e.g., mass loss, glacier acceleration, surface warming) due largely to the influence of the marine environment. WAIS is particularly vulnerable to large-scale atmospheric dynamics that remotely influence the transport of marine aerosols to the ice sheet. Understanding seasonal- to decadal-scale changes in the marine influence on WAIS (particularly sea-ice concentration) is vital to our ability to predict future change. In this thesis, I develop tools that enable us to reconstruct the source and transport variability of marine aerosols to West Antarctica in the past. I validate new firn-core sea-ice proxies over the satellite era; results indicate that firn-core glaciochemical records from this dynamic region may provide a proxy for reconstructing Amundsen Sea and Pine Island Bay polynya variability prior to the satellite era. I next investigate the remote influence of tropical Pacific variability on marine aerosol transport to West Antarctica. Results illustrate that both source and transport of marine aerosols to West Antarctica are controlled by remote atmospheric forcing, linking local dynamics (e.g., katabatic winds) with large-scale teleconnections to the tropics (e.g., Rossby waves). Oxygen isotope records allow me to further investigate the relationship between West Antarctic firn-core records and temperature, precipitation origin, sea-ice variability, and large-scale atmospheric circulation. I show that the tropical Pacific remotely influences the source and transport of the isotopic signal to the coastal ice sheet. The regional firm-core array reveals a spatially varying response to remote tropical Pacific forcing. Finally, I investigate longer-term (-200 year) ocean and ice-sheet changes using the methods and results gleaned from the previous work. I utilize sea-ice proxies to reconstruct long-term changes in sea-ice and polynya variability in the Amundsen Sea, and show that the tropics remotely influence West Antarctica over decadal timescales. This thesis utilizes some of the highest-resolution, most coastal records in the region to date, and provides some of the first analyses of the seasonal- to decadal-scale controls on source and transport of marine aerosols to West Antarctica.
Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 74. In a 1971 Scientific Committee on Antarctic Research report that reviewed polar contrasts in sea ice, Lyn Lewis and Willy Weeks made the following observation: "People who study sea ice in the Arctic Basin are commonly asked if they have ever studied ice in Antarctica, and they answer 'why bother, it's the same old stuff." Noting this was "fortunately true to a considerable extent," they added "It is clear that future work will depend critically on the logistics facilities available to allow surface observations beyond the fast ice edge at all seasons of the year. Of almost equal importance will be the development of instruments and recording equipment suited for use in the polar environment" (Lewis, E. L., and W. F. Weeks, Sea Ice: Some Polar Contrasts, in, Antarctic Ice and Water Masses, edited by G. Deacon, Scientific Committee on Antarctic Research, Cambridge, 23-34, 1971). Lewis and Weeks made no specific mention of Earth-orbiting satellites, on which the first passive microwave sensor became operational in December 1972. Less than a year later the giant Weddell Polynya was observed for the first time. Perhaps more than any other development, this unexpected feature illustrated the potential to greatly expand our knowledge of sea ice through the application of spaceborne remote sensing. Simultaneously, it acted as a catalyst for a significant increase in the level of research.
Antarctic Climate Evolution, Second Edition, enhances our understanding of the history of the world’s largest ice sheet, and how it responded to and influenced climate change during the Cenozoic. It includes terrestrial and marine geology, sedimentology, glacier geophysics and ship-borne geophysics, coupled with results from numerical ice sheet and climate modeling. The book’s content largely mirrors the structure of the Past Antarctic Ice Sheets (PAIS) program (www.scar.org/science/pais), formed to investigate past changes in Antarctica by supporting multidisciplinary global research. This new edition reflects recent advances and is updated with several new chapters, including those covering marine and terrestrial life changes, ice shelves, advances in numerical modeling, and increasing coverage of rates of change. The approach of the PAIS program has led to substantial improvement in our knowledge base of past Antarctic change and our understanding of the factors that have guided its evolution. Offers an overview of Antarctic climate change, analyzing historical, present-day and future developments Provides the latest information on subjects ranging from terrestrial and marine geology to sedimentology and glacier geophysics in the context of Antarctic evolution Fully updated to include expanded coverage of rates of change, advances in numerical modeling, marine and terrestrial life changes, ice shelves, and more
Surveys atmospheric, oceanic and cryospheric processes, present and past conditions, and changes in polar environments.
Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 73. The 4 million to 20 million square kilometers of sea ice that surrounds the Antarctic continent represents one of the largest and most dynamic ecosystems on Earth. This sea ice matrix provides a habitat for a wide variety of organisms, some of which live their entire lives within the ice while others are only occasional visitors. Large grazers, such as copepods and krill which come to the sea ice to feed, represent important links between sea ice biota and the pelagic environment. Unfortunately, because of the inherent difficulty of sampling such an environment, many aspects of this unique habitat are still poorly understood. The purpose of this volume is to present new information about this ecosystem so that its role within the Antarctic food-web (and as a sink for carbon dioxide) and its susceptibility to environmental changes can be better understood.
In this latest oceanology volume of the Antarctic Research Series, polar scientists describe and model air-sea and ice-ocean interactions, the formation and chemistry of deep and bottom waters, regional circulations, tidal heights and currents, ocean bathymetry, interannual variability and the Antarctic Slope Front.
Past Antarctica: Paleoclimatology and Climate Change presents research on the past and present of Antarctica in reference to its current condition, including considerations for effects due to climate change. Experts in the field explore key topics, including environmental changes, human colonization and present environmental trends. Addressing a wide range of fields, including the biosphere, geology and biochemistry, the book offers geographers, climatologists and other Earth scientists a vital resource that is beneficial to an understanding of Antarctica, its history and conservation efforts. Synthesizes research on the past and present of Antarctica, bringing together top Earth scientists who work in this discipline Presents the most complete reconstruction of the paleoclimate and environment of Antarctica, tying in long-term climatic changes to the current environment Offers perspectives from different branches of the Earth Sciences using a spatial-temporal lens