EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Reduction in ENSO variability during the mid-Holocene: a multi-model perspective

Shivangi Tiwari1, Francesco S. R. Pausata1, Allegra N. LeGrande2, Michael L. Griffiths3, Hugo Beltrami4, Anne de Vernal1, Clay R. Tabor5, Daniel Litchmore6, Deepak Chandan7, and W. Richard Peltier7
Shivangi Tiwari et al.
  • 1Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, Canada
  • 2NASA Goddard Institute for Space Studies, and Center for Climate Systems Research, Columbia University, USA
  • 3Department of Environmental Science, William Paterson University, USA
  • 4Department of Earth Sciences, St. Francis Xavier University, Canada
  • 5Department of Geosciences, University of Connecticut, USA
  • 6Department of Homeland Security - Federal Emergency Management Agency, USA
  • 7Department of Physics, University of Toronto, Canada

Paleoclimatic reconstructions have suggested a reduction inthe variability of the El Niño Southern Oscillation (ENSO) during the mid-Holocene (MH). Model simulations have largely failed to capture thisreduction, potentially due to the inadequate representation of the Green Sahara.The presence of a vegetated Sahara has been shown to have significant impacts on both regional and remote climate but remains inadequately addressed in Paleoclimate Modelling Intercomparison Project / Coupled Model Intercomparison Project (PMIP/CMIP) boundary conditions. Specifically, the incorporation of a Green Sahara has been shown to impact ENSO variability through perturbations to the Walker Circulation. In this study, we evaluate the MH (6,000 years BP) ENSO signatures of simulations from four models, namely —EC-Earth 3.1, iCESM 1.2, University of Toronto version of CCSM4 and GISS Model E2.1-G. Two simulations are considered for each model—a standard PMIP simulation (MHPMIP) with the mid-Holocene orbital parameters and greenhouse gas concentrations with vegetation prescribed to preindustrial conditions, as well as a Green Sahara simulation (MHGS) which additionally incorporates factors such as enhanced vegetation, reduced dust, presence of lakes, and land and soil feedbacks. All models show a reduction in ENSO variability due to the incorporation of Green Sahara conditions. This variability is interpreted in the context of perturbations to the Walker Circulation, triggered by the strengthening of the West African Monsoon.

How to cite: Tiwari, S., Pausata, F. S. R., LeGrande, A. N., Griffiths, M. L., Beltrami, H., de Vernal, A., Tabor, C. R., Litchmore, D., Chandan, D., and Peltier, W. R.: Reduction in ENSO variability during the mid-Holocene: a multi-model perspective, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4683,, 2023.