EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Volcanoes and ENSO: a re-appraisal with the Last Millennium Reanalysis

Feng Zhu1, Julien Emile-Geay1, Kevin Anchukaitis2,3,4, Greg Hakim5, Andrew Wittenberg6, Mariano Morales7,8, and Jonathan King3,4
Feng Zhu et al.
  • 1Department of Earth Sciences, University of Southern California, Los Angeles, CA USA
  • 2Laboratory of Tree-Ring Research, University of Arizona, Tucson AZ USA
  • 3School of Geography, Development, and Environment, University of Arizona, Tucson AZ USA
  • 4Department of Geosciences, University of Arizona, Tucson AZ USA
  • 5Department of Atmospheric Sciences, University of Washington, Seattle, WA USA
  • 6NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
  • 7Instituto Argentino de Nivologia, Glaciologa y Cs. Ambientales, Consejo Nacional de Investigaciones Cientficas y Tecnicas (CONICET), 5500 Mendoza, Argentina
  • 8Laboratorio de Dendrocronologiıa, Universidad Continental, 12003 Huancayo, Peru

The potential for explosive volcanism to affect the state of the El Niño-Southern Oscillation (ENSO) has been debated since the 1980s. Several observational studies, largely based on tree rings, have since found support for a positive ENSO phase in the year following large eruptions. Models of different complexities also simulate such a response, detectable above the backdrop of internal variability – though they disagree on the underlying mechanisms. In contrast, recent coral data from the heart of the tropical Pacific suggest no uniform ENSO response to all eruptions over the last millennium. Here we leverage paleoclimate data assimilation to integrate the latest paleoclimate evidence into a consistent dynamical framework and re-appraise this relationship. Our analysis finds only a weak statistical association between volcanism and ENSO, suggestive of either no causal association, or of an insufficient number of large volcanic events over the past millennium to obtain reliable statistics. While currently available observations do not support the model-based inference that tropical eruptions promote an ENSO response, there are hints of a response to hemispherically asymmetric forcing, consistent with the "ITCZ shift" mechanism. We discuss the difficulties of conclusively establishing a volcanic influence on ENSO given the many degrees of freedom affecting the response, including eruption season, spatial characteristics of the forcing, and ENSO phase preconditioning.

How to cite: Zhu, F., Emile-Geay, J., Anchukaitis, K., Hakim, G., Wittenberg, A., Morales, M., and King, J.: Volcanoes and ENSO: a re-appraisal with the Last Millennium Reanalysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-753,, 2021.

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