Read here. Map source here. Climate scientists have previously proposed that a 1,500 year oscillation driven by solar activity changes affects the climate, causing periodical warming and cooling cycles. A new study analyzing lake sediment cores from Bolivia confirms the existence of the approximate 1,500 year cycle.
"The five researchers report that their work "shows clear evidence of millennial-scale climate variation between ~60 and 20 ka BP," which was driven by variations in the degree of regional wetness; and they say that this climatic oscillation is well correlated with the stadial/interstadial oscillation of the North Atlantic region. More specifically, they write that "the correlation between the Lake Titicaca and NGRIP records suggests that the major cold periods in the North Atlantic region were synchronous with wet periods on the Altiplano.".....And this combined set of findings suggests that the approximate 1500-year climatic oscillation that alternately brings century-long periods of relative cold and warmth to the Northern Hemisphere impacts the hydrologic climate of the Southern Hemisphere on approximately the same time scale."
Additional climate history postings.