The original version of this Article omitted a reference to previous work in ‘Mann, M.E., Cane, M.A., Zebiak, S.E., Clement, A., Volcanic and Solar Forcing of the Tropical Pacific Over the Past 1000 Years, J. Climate18, 447–456 (2005)’. This has been added as reference 62 at the end of the fourth sentence of the fourth paragraph of the Introduction: ‘Early studies using simple coupled ocean–atmosphere models²⁶ proposed that following volcano-induced surface cooling, upwelling in the eastern equatorial Pacific acting on a reduced vertical temperature contrast between the ocean surface and interior leads to anomalous warming in this region, thereby favouring El Niño development the following year^{12, 27, 62}.’ This has been corrected in the PDF and HTML versions of the Article.