Weakened ENSO‐Ningaloo Niño/Niña Teleconnection Under Greenhouse Warming

• Published in: Geophysical research letters Vol. 48; no. 5
• Main Authors: Liu, Yi, Li, Ziguang, Cai, Wenju, Lin, Xiaopei, Yang, Jun‐Chao
• Format: Journal Article
• Language: English
• Published: 16.03.2021
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2020GL091326

Ningaloo Niño/Niña is a mode of climate variability in the southeastern Indian Ocean with huge impacts on Australian climate. El Niño‐Southern Oscillation (ENSO), as the dominant remote forcing, triggers Ningaloo Niño/Niña. However, how this teleconnection will respond to greenhouse warming is unclear. Using Coupled Model Intercomparison Project phase 5 (CMIP5) multimodel simulations, we find a weakened ENSO‐Ningaloo Niño/Niña teleconnection under greenhouse warming, which manifests as weakened atmospheric teleconnection from La Niña to Ningaloo Niño. Such weakened teleconnection can be linked to the tropical Pacific mean state changes including an El Niño‐like warming pattern and more stable atmosphere in the future climate, both suppressing the atmospheric convection in the western tropical Pacific, leading to a weaker Matsuno‐Gill response in the southeastern Indian Ocean. Our results suggest that Ningaloo Niño/Niña becomes more challenging to predict as greenhouse warming continues. Plain Language Summary Ningaloo Niño/Niña refers to an extreme ocean warming/cooling event off Western Australia with huge biological and climate impacts. El Niño‐Southern Oscillation (ENSO) is able to trigger Ningaloo Niño/Niña through atmospheric and oceanic processes, but this teleconnection is projected to weaken in the future climate. As greenhouse warming continues, the eastern tropical Pacific warms faster than the west, and the tropical atmosphere becomes more stable. These changes induce a suppressed atmospheric convection over the western tropical Pacific, the key region of teleconnection processes, and hence weaken the teleconnection. This study suggests a more challenging prediction of Ningaloo Niño/Niña by ENSO in a warmer climate. Key Points The El Niño‐Southern Oscillation (ENSO)‐Ningaloo Niño/Niña teleconnection is projected to weaken under greenhouse warming A weakened atmospheric teleconnection from La Niña to Ningaloo Niño contributes to this weakened ENSO‐Ningaloo Niño/Niña teleconnection The weakened ENSO‐Ningaloo Niño/Niña teleconnection is caused by the tropical Pacific mean state changes in the future