Evidence for decreased precipitation variability in the Yucatán Peninsula during the mid-Holocene

The Yucatan Peninsula has a complex hydroclimate with many proposed drivers of interannual and longer-term variability, ranging from coupled ocean-atmosphere processes to frequency of tropical cyclones. The mid-Holocene, thought to have had warmer north Atlantic sea surface temperatures, provides an interesting opportunity to test the relationship between Yucatan Peninsula precipitation and ocean temperature. Here we present a new, ~annually resolved speleothem record of stable isotope (δ18O and δ13C) and trace element (Mg/Ca and Sr/Ca) ratios for a section of the mid-Holocene (5.2-5.7 kyr BP). A meter-long stalagmite from Rio Secreto, a cave system in Playa del Carmen, Mexico, was dated using U-Th geochronology and layer counting, yielding ~decadal age uncertainty. The new proxy data were compared to a previously published late Holocene stalagmite from the same cave system, allowing us to examine changes in hydrology over time without potential inter-cave differences. The δ18O, δ13C and trace element data consistently indicate higher mean precipitation and lower precipitation variability during the mid-Holocene compared to the late Holocene. Despite this reduced variability, spectral analysis suggests that multi-decadal precipitation variations were persistent in regional hydroclimate during the mid- and late Holocene. Wet-dry oscillations occurred in association with the higher summer solar input and higher mean precipitation of the mid-Holocene, though with reduced amplitude compared to the late Holocene. We therefore conclude that the Yucatan Peninsula is susceptible to dry periods across climate mean states.