These changes in tropical Pacific Ocean
SSTs over the past millennium have often been associated with internal variability of the ocean - atmosphere system [19,27,53,54] that may not be accurately represented in current climate models.
Emile - Geay, J., Cobb, K. M., Mann, M. E. & Wittenberg, A. T. Estimating central equatorial Pacific
SST variability
over the
past millennium.