Comment on ''Deconvolving the @d^1^8O-seawater component from subseasonal coral @d^1^8O and Sr/Ca at Rarotonga in the southwestern subtropical Pacific for the period 1726 to 1997,'' by L. Ren, B. K. Linsley, G. M. Wellington, D. P. Schrag, and O Hoegh-Guld