The chemical and physical fingerprints of past El Niño events are preserved in ice cores from Andean glaciers, particularly the Quelccaya ice cap, and offer the potential to quantify past regional variability. Previous isotopic records provide a long annually resolved history (1,800 years) of Pacific sea surface temperature variations. However, the Quelccaya ice cap is also influenced by other internally varying climate system processes (e.g., South American Monsoon, Intertropical Convergence Zone position). Consequently, additional El Niño proxies are needed to reduce the uncertainties inherent in past El Niño reconstructions and to help facilitate more accurate projections of intensity and frequency.

This award uses funds, under the auspices of the NSF Rapid Response Research concept, to dig three new snow pits and collect two new ten-meter long cores from the Quelccaya ice cap in southern Peru. Samples from these pits and cores will be physically and chemically analyzed to address the hypotheses that post-depositional features (e.g., melt features) and elevated concentrations of dry deposited trace species (e.g., black carbon, dust, ammonium) provide new and reliable markers of past El Niño-Southern Oscillation (ENSO) events and also help facilitate the quantification of the event's intensity. These new markers will be also applied to other ice cores from the southern Andes that exist from extended tropical ice core archives collected over the last forty years.