@article {thompson_use_2022,
	title = {Use of δ18Oatm in dating a Tibetan ice core record of Holocene/Late Glacial climate},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {119},
	number = {45},
	year = {2022},
	note = {Publisher: Proceedings of the National Academy of Sciences},
	month = {11/2022},
	pages = {e2205545119},
	abstract = {Ice cores from the northwestern Tibetan Plateau (NWTP) contain long records of regional climate variability, but refrozen meltwater and dust in these cores has hampered development of robust timescales. Here, we introduce an approach to dating the ice via the isotopic composition of atmospheric O2 in air bubbles (δ18Oatm), along with annual layer counting and radiocarbon dating. We provide a robust chronology for water isotope records (δ18Oice and d-excess) from three ice cores from the Guliya ice cap in the NWTP. The measurement of δ18Oatm, although common in polar ice core timescales, has rarely been used on ice cores from low-latitude, high-altitude glaciers due to (1) low air pressure, (2) the common presence of refrozen melt that adds dissolved gases and reduces the amount of air available for analysis, and (3) the respiratory consumption of molecular oxygen (O2) by micro-organisms in the ice, which fractionates the δ18O of O2 from the atmospheric value. Here, we make corrections for melt and respiration to address these complications. The resulting records of water isotopes from the Guliya ice cores reveal climatic variations over the last 15,000 y, the timings of which correspond to those observed in independently dated lake and speleothem records and confirm that the Guliya ice cap existed before the Holocene. The millennial-scale drivers of δ18Oice are complex and temporally variable; however, Guliya δ18Oice values since the mid-20th century are the highest since the beginning of the Holocene and have increased with regional air temperature.},
	doi = {10.1073/pnas.2205545119},
	url = {https://www.pnas.org/doi/10.1073/pnas.2205545119},
	author = {Thompson, Lonnie G. and Severinghaus, Jeffrey P. and Yao, Tandong and Davis, Mary E. and Mosley-Thompson, Ellen and Beaudon, Emilie and Sierra-Hern{\'a}ndez, M. Roxana and Porter, Stacy E.}
}
@article { ISI:000269223500001,
	title = {Recently exposed vegetation reveals Holocene changes in the extent of the Quelccaya Ice Cap, Peru},
	journal = {QUATERNARY RESEARCH},
	volume = {72},
	number = {{2}},
	year = {2009},
	month = {SEP},
	pages = {157-163},
	type = {Article},
	abstract = {Radiocarbon dating of well-preserved, in-place vegetation exposed by the retreating Quelccaya Ice Cap of southeastern Peru constrains the last time the ice cap{\textquoteright}s extent was smaller than at present. Seventeen plant samples from two sites along the central western margin collectively date to 4700 and 5100 cal yr BP and strongly indicate that current ice cap retreat is unprecedented over the past similar to 5 millennia. Seventeen vegetation samples interbedded in a nearby clastic sedimentary sequence suggest ice-free conditions at this site from similar to 5200 to at least similar to 7000 cal yr BP, and place minimum constraint on early- to mid-Holocene ice cap extent. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.},
	keywords = {14C dating, Andes, Climate change, Glacier retreat, Holocene, Peru, Quelccaya Ice Cap, South America, Tropical glaciers},
	issn = {0033-5894},
	doi = {10.1016/j.yqres.2009.02.007},
	author = {Buffen, Aron M. and Thompson, Lonnie G. and Mosley-Thompson, Ellen and Huh, Kyung In}
}
