Solar forcing of drought frequency in the Maya lowlands

We analyzed lake-sediment cores from the Yucatan Peninsula, Mexico, to reco nstruct the climate history of the region over the past 2600 years. Time se ries analysis of sediment proxies, which are sensitive to the changing rati o of evaporation to precipitation (oxygen isotopes and gypsum precipitation ), reveal a recurrent pattern of drought with a dominant periodicity of 208 years. This cycle is similar to the documented 206-year period in records of cosmogenic nuclide production (carbon-14 and beryllium-10) that is thoug ht to reflect variations in solar activity. We conclude that a significant component of century-scale variability in Yucatan droughts is explained by solar forcing. Furthermore, some of the maxima in the 208-year drought cycl e correspond with discontinuities in Maya cultural evolution, suggesting th at the Maya were affected by these bicentennial oscillations in precipitati on.