HIGH RESOLUTION ANTARCTIC GLACIOCHEMICAL CLIMATE PROXY RECORDS AND THEIR GLOBAL IMPLICATIONS

high resolution antarctic GLACIOCHEMICAL climate proxy records and thEIr global implications

By Daniel Arthur Dixon

Thesis Advisor: Dr. Paul A. Mayewski

An Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Doctor of Philosophy

(in Earth Sciences)

May, 2011

The first section of this study presents an in-depth chemical analysis from a series of surface snow samples and shallow ice cores collected along four US ITASE traverses across extensive regions of East and West Antarctica. Each surface snow sample was analyzed for more than 25 dissolved, total, and stable oxygen isotope chemical concentrations. This provides a baseline from which changes in the chemistry of the atmosphere over Antarctica can be monitored. We must monitor these changes as greenhouse gas induced warming and intensification of industrial activities in the Southern Hemisphere continues.  It is of utmost importance to pay close attention to changes in Antarctica. Even small changes there can have profound affects on global climate.

The surface of Antarctica is inherently complex, making it a challenge to track these changes. Satellite maps of snow crystal grain size and surface reflection from the Antarctic ice sheet assist in the identification of glazed dune areas across Antarctica. Correlations between these maps and surface snow chemistry show how chemical concentrations are higher in glazed dune areas, precluding them from containing easily interpreted chemical climate records. The majority of the non-glazed dune samples in this study exhibit similar, or lower, chemical concentrations to those from previous studies. Consequently, the results presented here comprise a conservative chemical framework for Antarctic surface snow studies.

The second section of this study presents a 200-year record for Northerly Air Mass Incursions (NAMI) into central and western West Antarctica. The NAMI record is developed from the examination of 19 shallow (21m – 150m deep) Antarctic ice core non-marine calcium concentration records and it exhibits a significant rise in recent decades. This rise is unprecedented for at least the last 200 years and is coincident with anthropogenically-driven changes in other large-scale Southern Hemisphere (SH) environmental phenomena such as greenhouse gas induced warming, ozone depletion and the associated intensification of the SH westerly winds. Statistical analysis suggests that atmospheric circulation is the dominant factor affecting non-marine calcium concentrations throughout central and western West Antarctica.