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

KEVIN ANCHUKAITIS; MARIANO S. MORALES; JULIEN EMILE-GEAY; GREGORY J. HAKIM; JONATHAN KING; FENG ZHU; ANDREW T. WITTENBERG

San Francisco

Conferencia; AGU fall meeting; 2020

American Geophysical Union

There is ongoing controversy as to the role of explosive volcanism in shaping ENSO behavior, with implications for our understanding of ENSO fundamentals and the safety of geoengineering scenarios. The prevailing view is that sulfate aerosol loading above a certain threshold can shift the odds in favor of a warm ENSO phase the year following an eruption. This view is borne out by models spanning a range of complexity, though there is no consensus on the underlying mechanism [e.g. Emile-Geay et al, 2008, McGregor and Timmerman 2010, Stevenson et al, 2016, Khodri et al, 2017, Pausata et al, 2020]. The relationship also seems borne out by reconstructions of ENSO state [McGregor et al, 2020], which are largely based on extratropical, moisture-sensitive tree-ring chronologies. In contrast, a new, precisely dated coral record from the heart of the tropical Pacific suggests no consistent ENSO response to volcanic forcing over the last millennium [Dee et al, 2020].