A question of timing: a comment on Hong, Jiang, Lui, Zhou, Beer, Li, Leng,Hong and Qin

Hong et al. (2000) claim to have demonstrated a direct link between Holocen e solar variability and delta O-18 variations in a peat core from China. Th is comment suggests that the proposed link rests on an inferred relationshi p between delta O-18 and air temperature that requires validation; moreover , the chronological control is not adequate to support the correlations wit hout some degree of unverifiable tuning. The interesting conclusions drawn by the authors thus require further testing before they can be accepted. Th e growing tendency to infer poorly constrained correlations with targets th at reflect variability, whether of external forcing or widely accepted clim ate responses, can often be counter-productive, despite its long history in Quaternary science.