| Summary: | Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2019 Cataloged from PDF version of thesis. Includes bibliographical references. The Common Era (A.D. 1- present) represents a crucial period for climatic studies, documenting the timespan over which human activities have become an increasingly domineering force in shaping Earth's landscape, climate, and ecology. Direct, quantifiable records of climatic phenomena are severely limited over much of the Common Era, necessitating high-resolution, naturally-derived proxies to extend climatic insights beyond the satellite and instrumental era, particularly across remote high-latitude and maritime regions of the North Atlantic. Here, I use modem, data-driven and physically-based modeling approaches to gain new insights into North Atlantic climate variability from the Greenlandic ice core archive. First, I investigate the climatic fidelity of ice core glaciochemical climate proxies at the microphysical-scale. I show that several soluble chemical species - key among them methanesulfonic acid (MSA) - undergo rapid vertical migration through a super-cooled liquid-advection process along ice crystal grain-boundaries. I demonstrate that significant multi-year MSA changes occur only under low snow-accumulation and high-impurity-content conditions, thus mitigating the phenomenon over much of Greenland. Building upon these findings, I then investigate the cause of declining 19th and 20th-century MSA concentrations across the interior Greenland Ice Sheet. My results illustrate that Greenlandic MSA records provide a new proxy for North Atlantic planktonic biomass changes, illuminating a 10 ± 7% decline in marine productivity over the Industrial-era. I next present a new climate record from a previously-unexplored coastal ice cap in west-central Greenland. Using a physically-constrained ice cap ...
|
|---|