So many papers present interesting palaeo-data and then add a badly done analysis that attempts to prove that the palaeo-data correlate (if you squint hard enough) with the Carriaco Basin record, NGRIP or the solar insolation reconstruction. This is not a good state of affairs: no amount of correlation-by-eye or bodged spectral analysis will ever provide evidence of anything.
I don’t know why authors feel compelled to do this. Perhaps they think they cannot publish their record without making the paper “sexy” by explaining the record in terms of climate forcings or correlations with other records.
It doesn’t have to be this way. Wilhelm et al have a new millennium-long flood record under review at Climate of the Past Discussion in which they explicity decline to try to explain the record with external forcings with simplistic analyses.
… external forcing such as solar activity, and volcanic eruptions largely varied over the last millennium (e.g. Servonnat et al., 2010; Delaygue et Bard, 2011; Gao et al., 2012; Crowley and Unterman, 2013) and their non-linear combination also with the greenhouse gases may result in different time-space temperature patterns and, thereby, in different flood responses during these two periods. In order to explore forcing-dependent impacts on the climate–flood relationships, deeper analysis utilizing for example advanced statistics or simulations is required.
I just hope the reviewers won’t require them to test for correlations with forcings.