Impacts of Low-Frequency Internal Climate Variability and Greenhouse Warming on El Niño–Southern Oscillation

• DOI: 10.1175/jcli-d-20-0232.1
• Publication Date: 2020-12-21T18:42:38Z
• Authors: Benjamin Ng; Wenju Cai; Tim Cowan; Daohua Bi
• Keywords: 13. Climate action; Climate change; Tropical variability; ENSO; 551; 16. Peace & justice; 01 natural sciences; El Nino; 0105 earth and related environmental sciences

Abstract El Niño–Southern Oscillation (ENSO) is the dominant mode of interannual climate fluctuations with wide-ranging socioeconomic and environmental impacts. Understanding eastern Pacific (EP) central (CP) Niño response to a warmer paramount, yet role internal variability in modulating their not clear. Using large ensembles, we find that generates spread standard deviation skewness these two types similar 17 models from phase 5 Coupled Model Intercomparison Project (CMIP5) realistically simulate ENSO diversity. Based on 40 Community Earth System Large Ensemble (CESM-LE) 99 Max Planck Institute for Meteorology Grand (MPI-GE) members, unforced can explain more than 90% historical EP CP all CMIP5 models. Both CESM-LE selected show increased climate, driven by stronger mean vertical temperature gradient upper ocean faster surface warming equatorial Pacific. However, MPI-GE shows no agreement or change. This due weaker sensitivity signal, such when faster, change tends be weaker. highlights individual produce different considerable uncertainty within ensemble may caused variability.