Reconstructing and Understanding How Past Warming Affected Sea Level, Ice Sheets, And Permafrost

• Main Author: Creel, Roger Cameron
• Format: Thesis
• Language: English
• Published: 2024
• Subjects: Global warming; Geophysics; Paleoclimatology; Ice sheets; Permafrost; Sea level > Research; Quaternary Geologic Period; Mantle of the Earth; Antarc*; Antarctic; Fennoscandian; Ice; Ice Sheet; Norwegian Sea; permafrost
• Online Access: https://doi.org/10.7916/z0bg-nz57

Natural climate variability over the past hundreds of thousands of years provides a uniquewindow into the drivers and processes that connect different parts of our climate system. This thesis investigates interactions between Earth’s mantle, its oceans, and ice sheets over the Quaternary. The dominant process that connects these spheres is glacial isostatic adjustment (GIA), which is the deformation of Earth’s mantle (and consequently its surface, gravity field, and sea level) in response to changes in ice and ocean mass loading. This dissertation focuses on time periods during which surface temperatures were warming or warmer than today to understand how these warm intervals affected ice sheets, permafrost, and sea level. I put my results in the context of current and future warming to improve predictions of future change and compare natural to anthropogenic variability. The thesis opens with an investigation of relative (i.e., local) sea level around Norway overthe last 16 thousand years (ka). Postglacial Norwegian sea level, though dominated by postglacial rebound and associated sea-level fall, is punctuated by two periods of sea-level rise. The causes of these episodes, named the ‘Tapes’ and ‘Younger Dryas’ transgressions, remain debated despite more than a century of study. I produce the first standardized and quality-controlled compilation of Norwegian sea-level data, then employ an ensemble of empirical Bayesian hierarchical statis- tical models to estimate relative sea level along the Norwegian coastline. The resulting model enables an examination of the relative contributions of isostatic rebound and global mean sea-level (GMSL) rise to the Tapes transgression, and lays the foundation for future applications such as in- version of sea-level data for Fennoscandian ice-sheet volume and the comparison of modern rates of Norwegian sea-level rise to pre-industrial rates. Chapter Two aims to better understand sea-level and Antarctic ice-sheet variability during the Holocene, which is the last time global ...