Three Centuries of ENSO Variability Inferred From Muna, Sulawesi, Indonesia Teak <i>δ</i> ¹⁸ O: Limited Response to Radiative Forcing

Abstract We present an annual resolution oxygen isotope anomaly (O c ) record, derived from eight teak ( Tectona grandis L.f. ) tree ring‐dated O c series from Muna, Southeast Sulawesi, Indonesia (5.3S, 123E). The record is significantly correlated (, edf = 82, p &lt; 0.01) with the October–September averaged NINO34 sea surface temperature index, 1856–2005. We find a significant tendency toward ENSO warm phase events in the year following volcanic eruptions, 1668–1900, n = 29 events, p = 0.05, no change arising from solar activity, 1751–2005, and no change in ENSO event distribution, 1681–2005. The latter result suggests either a weak forced signature is not yet emergent, given substantial observational uncertainty, or else that the response of ENSO amplitude and/or event frequency to greenhouse forcing over the past three centuries is within the envelope of unforced variability. These findings are consistent with some paleoclimate reconstructions, but contrast with others and some model projections of increased ENSO variability under recent anthropogenic forcing.