Coherent Holocene Expansion of a Tropical Andean and African Glacier
Vickers, Anthony Cole. “Coherent Holocene Expansion of a Tropical Andean and African Glacier”, MS, Boston College, 2018. http://hdl.handle.net/2345/bc-ir:108253.
Glaciers in the tropics have undergone significant retreat in the past several decades, but the magnitude of this retreat in the long-term context of the Holocene has mostly been qualitatively assessed. This study produces a quantitative reconstruction of Holocene glacier extent relative to today from the Quelccaya Ice Cap, Peru, and the Rwenzori Mountains of east Africa. I use measurements of in situ 14C and 10Be from bedrock that was recently exposed by glacier retreat to constrain possible bedrock exposure and erosion histories at each site. The results are strikingly similar in both areas, and suggest that ice was generally smaller than today during the first half of the Holocene and larger than today for most, if not all, of the last several millennia. These findings give evidence toward a coherent Holocene expansion of glaciers across the tropics, and suggest that recent retreat is unusual in a multi-millennial context.