Huascarán

Overview (1993)

Between 1990 and 1992 a survey of five glaciers located north-south along the Cordillera Blanca was conducted to identify the best sites for acquiring longer-term paleoclimatic and environmental records. In addition, satellite-linked automatic weather stations were established on two of the sites, Hualcán and Pucahirca, to record current meteorological conditions at the top of the Andes. The col of Huascarán (9^o06'41" S; 77^o36'53" W), the highest (6048 m a.s.l) and coldest of the sites, was selected for drilling to bedrock as shallow cores from all five sites confirmed that it contained the best preserved stratigraphic records. In 1993 two ice cores were drilled to bedrock using a portable, light-weight, solar-powered thermal drilling system. Core 1 (C1), 160.4 m long (152.41 m ice eq.), was cut in the field into 2677 samples, which were melted and poured into bottles and sealed with wax. Core 2 (C2), 166.1 meters long (158.44 m ice eq.), was returned frozen to The Ohio State University, where it was cut into 4675 samples. Samples from both cores were analyzed for microparticle concentrations (dust), chloride ( Cl^- ), nitrate (NO₃^-) and sulfate (SO₄^2-) concentrations, and ¹⁸O and D.

The following paper (abstract is clickable) summarizes the results from the Huascaran cores.

Thompson, L.G., E. Mosley-Thompson, M.E. Davis, P-N. Lin, K.A. Henderson, J. Cole-Dai, J.F. Bolzan and K-b. Liu. 1995. Late Glacial Stage and Holocene tropical ice core records from Huascarán, Peru. Science, 269, 46-50.

Overview (2019)

During a reconnaissance mission to Nevado Huascarán in July 2016, researchers from the Byrd Polar and Climate Research Center recovered a 10.9 m firn core from the mountain’s col (6050 m above sea level). Subsequent laboratory measurements showed that, unlike other tropical ice cores from Peru, the seasonal δ18O profile at Huascarán remains undisturbed [Thompson et al. 2017].

In August 2019, researchers returned to Huascarán to drill the first ice cores to bedrock since the original campaign in 1993 [Thompson et al. 2023]. This included two cores from the mountain col (Col Core A and Col Core B) that measured 165.0 m and 168.6 m in length, respectively, as well as the first-ever cores drilled form the mountain summit (6768 m above sea level). The summit cores (Summit Core A and Summit Core B) measured 69.3 m and 68.7 m in length, respectively. To date, these are the highest-elevation ice core records ever obtained from the tropics. Annually-resolved oxygen stable isotope (δ18O) and net accumulation records have since been reported for the col and summit cores that extend through the most recent six decades [Weber et al. 2023]. Preliminary black carbon measurements have also been reported [Bonilla et al. 2023].

References

Bonilla, E. X., Mickley, L. J., Beaudon, E. G., Thompson, L. G., Rodriguez, W. E., Encarnación, R. C., Whicker, C. A., Flanner, M. G., Schmitt, C. G., & Ginot, P. (2023). Contribution of biomass burning to black carbon deposition on Andean glaciers: Consequences for radiative forcing. Environmental Research Letters, 18(2), 024031. https://doi.org/10.1088/1748-9326/acb371 

Thompson, L. G., Davis, M. E., Mosley‐Thompson, E., Beaudon, E., Porter, S. E., Kutuzov, S., Lin, P. ‐N., Mikhalenko, V. N., & Mountain, K. R. (2017). Impacts of Recent Warming and the 2015/2016 El Niño on Tropical Peruvian Ice Fields. Journal of Geophysical Research: Atmospheres, 122(23). https://doi.org/10.1002/2017JD026592 

Thompson, L. G., Mosley-Thompson, E., Schoessow, F., Davis, M. E., Sierra-Hernandez, R., Beaudon, E., & the Huascarán team. (2023). The challenges, successes, and preliminary status report on the 2019 recovery of ice cores from Nevado Huascarán, Earth’s highest tropical mountain. Revista de Glaciares y Ecosistemas de Montaña, 8, 31-42. PDF 

Weber, A. M., Thompson, L. G., Davis, M., Mosley-Thompson, E., Beaudon, E., Kenny, D., Lin, P.-N., & Sierra-Hernández, R. (2023). Drivers of δ18O Variability Preserved in Ice Cores From Earth’s Highest Tropical Mountain. Journal of Geophysical Research: Atmospheres, 128(19), e2023JD039006. https://doi.org/10.1029/2023JD039006