Peruvian Stalagmites as Indicators of Past Climate: an investigation of MIS 8 and 9

By studying past climates throughout Earth\u27s history, we can put current climate change into perspective. Over the past century, we have witnessed an unprecedented warming of the Earth but still do not understand how various regions, such as the tropics, will respond to global change. Through natural archives, paleoclimatology tells us the degree to which the human- induced warming taking place deviates from the past. Cave speleothems can be used to uncover historic precipitation patterns and monsoon cycles. I studied oxygen and carbon isotope records from a stalagmite collected from Huagapo Cave in the Upper Amazon Basin of the Peruvian Andes in order to investigate regional glacial cycles in comparison to other local paleoclimate records. The stalagmite grew from approximately 310 to 245 ka, with δ18O values ranging from - 12.44 to -17.34‰ and δ13C values from -5.82 to 1.90‰. Spanning the entirety of MIS 8, it captures a glacial period and the beginning of the interglacial MIS 9. The isotope record tracks solar insolation and supports the hypothesis that glacial periods in the tropics are wet. The precision of U-Th dating in stalagmites presents an opportunity to adjust chronologies from other paleoclimate proxies. This record was compared to sediment cores from Lake Júnin and a global record of benthic foraminifera in an effort to finely tune existing paleoclimate data. This stalagmite expanded Union College\u27s current isotope record by nearly 70,000 years and will assist in the creation of a high-resolution isotope record of the tropic region