What was done
The authors analyzed variations in multiproxy palaeoclimate data, including magnetic susceptibility, calcium carbonate content and total organic carbon, from numerous sediment cores taken from two lakes (Myall and Tuggerah) in different drainage basins of temperate eastern Australia to identify how the climate has fluctuated in this region during the Holocene.  Specifically, spectral analysis was performed on the sediment core data, but because of limitations in data sampling, as well as the sedimentation rates within the two lakes, only periodicities within the range of 200 to 2,000 years were able to be determined.

What was learned
The results of the analysis revealed strong periodicities in sediments from both lakes at approximately 210, 250, 350-370, 420, 500-530 and 1250-1450 years, all of which periods, according to the authors, "have been identified in other palaeoclimate studies of stratigraphic data ... and can be attributed to variations in solar insolation or perturbations in orbital cycles brought about by feedback loops."

What it means
Because the two lakes are not situated within the same catchment area and drain different basins, yet demonstrate similar centennial- and millennial-scale periodicities, suggests to us that the authors' thesis of a solar-climate connection is probably the only reasonable explanation for the source of the centennial- and millennial-scale variability observed in the records.  This observation makes it difficult for climate alarmists to build a solid case for modern CO2-induced climate forcing, for if all of these multiple-scale solar forcings have been major determinants of climate change in the past, there is no way we can rule them out as having played major roles in driving modern climate change.