10-3 Constraining Triple Oxygen Isotope Signatures of Precipitation During the 2023-2024 Strong El Niño in the Western US

Session: Geochemistry and Mineralogy (Posters)

Presenting Author:

Authors:

Abstract:

It is uncertain how the hydroclimate of the Western US will respond to warmer temperatures driven by anthropogenic climate change. In particular, predicting the impact of future El Niño Southern Oscillation (ENSO) events is complicated by various factors, such as differences in projected precipitation between models and the difficulty of untangling SST changes from climate change with the natural internal variability of the ENSO system. Stable isotope techniques can allow for monitoring of these hydrological processes by constraining how ENSO is affected by changes in climate and its influence on the Western US hydroclimate—dynamics imperative to understand, as ENSO events significantly impact precipitation patterns.

Here, we analyze precipitation samples collected from 27 stations across the Western US during the 2023-2024 El Niño event for their δ2H, δ18O, d-excess, and Δ’¹⁷O signatures. Notably, the data will provide the first Δ’¹⁷O record to span an El Niño event and give insight into whether it captures hydroclimate changes associated with ENSO or reflects similar processes captured by d-excess. Results show mean seasonal Δ’¹⁷O values of 31.5 ± 4.2 per meg (winter), 33.4 ± 4.4 per meg (spring), 15.2 ± 3.9 per meg (summer), and 9.6 ± 4.0 per meg (fall) across all stations, potentially indicative of distinct seasonality. We also compare our data to the modeled long-term average isotope values from the Online Isotopes in Precipitation Calculator (OIPC) and previous observations to determine the isotopic anomalies caused by El Niño. These analyses will contribute to a better understanding of how ENSO events affect triple oxygen isotope signatures and provide constraints and interpretations for Δ’¹⁷O as a new geochemical proxy, aiding water management and a better understanding of past, present, and future climates.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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