What was done
Several times a year, northwesterly winter monsoonal winds carry dust from the inner part of China all the way to Korea and the East China Sea.  In the present study, the authors examined the eolian quartz content (EQC) of a high-resolution sedimentary core taken from Cheju Island, Korea (33°21'15.6"N, 126°37'32.4"E), producing a proxy record of major Asian dust events reaching this region over the past 6500 years.  They then compared this record with a proxy record of solar activity in an effort to determine if there was any link between them.

What was learned
Results of the analysis indicate that the EQC was relatively low from 6500-4000 yr BP, high between 4000-2000 yr BP, and low again from 2000 yr BP to the present, with the most recent 1500 yr BP being lower in EQC than at any previous time in the record.  The Asian dust time series was also found to contain significant millennial- and centennial-scale periodicities.  Cross-spectral analysis between the EQC and proxy solar activity record showed significant coherent cycles at 700, 280, 210 and 137 yr with "nearly the same phase changes, leading the authors to conclude that the centennial-scale periodicities in the EQC can be ascribed mainly to short-term fluctuations in solar activity.

What it means
The results of this study highlight the need to improve our understanding of mechanisms controlling sun-atmosphere-monsoon linkages.  Clearly, as we have often indicated in other Journal Reviews (see the many items we have posted in the various sub-headings of Solar Effects in our Subject Index), the sun plays an important role in climate change on earth; and that role must be fully understood before we can determine the degree of influence of any anthropogenic forcing that may be playing a similar role.