Uncertainty in El Niño-like warming and California precipitation changes linked by the Interdecadal Pacific Oscillation

• Published in: Nature communications Vol. 12; no. 1; pp. 6484 - 10
• Main Authors: Dong, Lu, Leung, L. Ruby, Song, Fengfei, Lu, Jian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.11.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/35/823; 704/106/694/2786; Adaptation; Climate change; Climate models; Communication; El Nino; Global warming; Humanities and Social Sciences; multidisciplinary; Precipitation; Science; Science (multidisciplinary); Teleconnections; Uncertainty; Variability; Water stress; United States > US; California
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26797-5

Marked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under global warming, a westerly jet extension in the North Pacific analogous to the El Niño-like teleconnection has been suggested as a key mechanism for CA winter precipitation changes. However, this teleconnection has not been reconciled with the well-known El Niño-like warming response or the controversial role of internal variability in the precipitation uncertainty. Here we find that internal variability contributes > 70% and > 50% of uncertainty in the CA precipitation changes and the El Niño-like warming, respectively, based on analysis of 318 climate simulations from several multi-model and large ensembles. The Interdecadal Pacific Oscillation plays a key role in each contribution and in connecting the two via the westerly jet extension. This unifying understanding of the role of internal variability in CA precipitation provides critical guidance for reducing and communicating uncertainty to inform adaptation planning. There is a strong disagreement between climate models on how precipitation in California will change. Here, the authors show that much of this uncertainty originates from internal variability with the Interdecadal Pacific Oscillation linking the precipitation changes with the El Niño-like warming pattern through the westerly jet extension