Portland State University PDXScholar Dissertations and Theses Dissertations and Theses 2008 Quantifying Twentieth Century Glacier Change in the Sierra Nevada, California Hassan J. Basagic Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Geology Commons, Glaciology Commons, and the Physical and Environmental Geography Commons Let us know how access to this document benefits ou.y Recommended Citation Basagic, Hassan J., "Quantifying Twentieth Century Glacier Change in the Sierra Nevada, California" (2008). Dissertations and Theses. Paper 2239. https://doi.org/10.15760/etd.2236 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. THESIS APPROVAL The abstract and thesis of Hassan Jules Basagic IV for the Master of Science in Geography were presented May 5, 2008, and accepted by the thesis committee and the department. COMMITI'EE APPROVALS: /'.,drew G. Fountain, Chair DEPARTMENT APPROVAL: Martha A. Works, Chair Department of Geography ABSTRACT An abstract of the thesis of Hassan Jules Basagic IV for the Master of Science in Geography presented May 5, 2008. Title: Quantifying Twentieth Century Glacier Change in the Sierra Nevada, California Numerous small alpine glaciers occupy the high elevation regions of the central and southern Siena Nevada, California. These glaciers change size in response to variations in climate and are therefore important indicators of climate change. An inventmy based on USGS topographic maps (l :24,000) revealed 1719 glaciers and 2 perennial snow and ice features for a total area of39.l5 ±7.52 km • The number of 'true' glaciers, versus non-moving ice, is estimated to be 118, covering 15.87 ± 1.69 2 km • All glaciers were located on north to nmtheast aspects, at elevations >3000 m. Historical photographs, geologic evidence, and field mapping were used to detetmine the magnih1de of area loss over the past cenh1ry at 14 glaciers. These glaciers decreased in area by 31% to 78%, averaging 55%. The rate of area change was detetmined for multiple time periods for a subset of seven glaciers. Rapid retreat occmred over the first half of the twentieth cenh1ry beginning in the 1920s in response to warm/dry conditions and continued through the mid-1970s. Recession ceased during the early 1980s, when some glaciers advanced. Since the 1980s each of the seven study glaciers resumed retreat. The uniform timing of changes in area amongst study glaciers suggests a response to regional climate, while the magnitude of change is influenced by local topographic effects. Glacier area changes correlate with changes in spring and summer air temperatures. Winter precipitation is statistically urn-elated to changes in glacier area. Headwall cliffs above the glaciers alter the glacier responses by reducing incoming shortwave radiation and enhancing snow accumulation via avalanching. 2 QUANTIFYING TWENTIETH CENTURY GLACIER CHANGE IN THE SIERRA NEVADA, CALIFORNIA by HASSAN JULES BASAGIC IV A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE m GEOGRAPHY Portland State University 2008 ACKNOWLEDGMENTS I would like to thank my advisor, Andrew G. Fountain, for his support and guidance during this research, and my committee members, Keith S. Hadley and Martin D. Lafrenz, for their valuable insights. I would like to acknowledge staff at Sequoia & Kings Canyon National Parks (SEKI) for their help, including Pat Lineback, Sylvia Haultain, Tony Caprio, Nate Stephenson (USGS BRD), and Hal Pranger at the Geologic Resources Division. I am especially grateful to Danny Boiano and Annie Esperanza for their help in developing this project and for their support and encouragement. I appreciate the hard work provided in the field by Danny Boiano, Shane Ftyer, Alysha Wilson, Ryan Branciforte, Jeff Kane, Jennifer Hook, and Rhonda Robb. Thanks for helping to carry heavy loads in difficult terrain. I would also like to thank archive staff who helped me locate photographs including Ward Eldredge (SEKI), Linda Eade (Yosemite NP), William Ketwin and Linda Reynolds (USFS Bishop). I thank Douglas Hardy for use of his Yosemite glacier photos. I benefited greatly from conversations with Keith Jackson, Matt Hoffman, and Peter Sniffen. Most importantly I thank my family for their support and encouragement throughout this process. Support for this research came from the National Park Service, including Sequoia & Kings Canyon National Parks and the Geologic Resource Division, the National Science Foundation (BCS-0351004), and NASA (NNG04GJ41 G). I thank SEKI for their support through the Student Career Employee Program. TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................................... i LIST OF TABLES ........................................................................................................ iv LIST OF FIGURES ........................................................................................................ v 1. INTRODUCTION ...................................................................................................... ! 2. STUDY AREA ........................................................................................................... 6 Previous Glacier Studies .......................................................................................... 10 3. GLACIER POPULATION INVENTORY .............................................................. 13 Introduction .............................................................................................................. 13 Methods .................................................................................................................... 13 Results ...................................................................................................................... 15 4. GLACIER CHARACTERISTICS AND TEMPORAL CHANGE ......................... 25 Study Glaciers .......................................................................................................... 25 Temporal change database ....................................................................................... 35 Results ...................................................................................................................... 39 5. CLIMATE ANALYSIS ............................................................................................ 48 Introduction .............................................................................................................. 48 Methods .................................................................................................................... 48 Results ...................................................................................................................... 49 6. TOPOGRAPHIC ANALYSIS ................................................................................. 60 Introduction .............................................................................................................. 60 Topographic characteristics ...................................................................................... 62 Change in mean glacier conditions .......................................................................... 65 Case study at Lyell Glacier ...................................................................................... 69 7. DISCUSSION AND CONCLUSION ...................................................................... 74 8. REFERENCES CITED ............................................................................................ 79 Appendix A. USGS Maps with Glaciers ...................................................................... 87 Appendix B. Repeat Photography ................................................................................ 89 Appendix C. Glacier Change Metadata ........................................................................ 96 11 Appendix D. Rates of Glacier Area Change for Seven Glaciers .................................. 99 Appendix E. Glacier Area Change Maps and Area-Altitude Distributions for Seven Study Glaciers ............................................................................................................ 100 SUPPLEMENTAL CD Glacier inventory table lll LIST OF TABLES 2 Table 1. Comparison of ~lacier area (km ) statistics for the glacier population, glaciers with area >0.01 km , and glaciers with calculated shear stress> 105 Pa .............. 21 Table 2. Comparison of glacier inventories ................................................................. 22 Table 3. Locations of the study glaciers. Names in bold are those selected for in depth study over time. Names in italics are informal glacier names. Area and topographic characteristics are based on the population inventory. Elv = elevation 0 (meters), Sip= slope CO), Asp= aspect ( ) ••••.••••••••••••••••••••••••••••••••••••••••••••••••••••••• 26 Table 4. Size comparison of glaciers >0.01 km2 and selected study glaciers .............. 33 Table 5. Study glaciers with the number of extents and time range of available data. Names in bold are those selected for in depth study over time. Asterisk indicates extent based solely on moraine position............................................................... 40 2 Table 6. Comparison of three