Solar Forcing of Early Holocene Droughts on the Yucatán Peninsula

Abstract

A speleothem record from the north-eastern Yucatán peninsula (Mexico) provides new insights into the tropical hydro-climate of the Americas between 11,040 and 9,520 a BP on up to sub-decadal scale. Despite the complex atmospheric reorganization during the end of the last deglaciation, the dominant internal leading modes of precipitation variability during the late Holocene were also active during the time of record. While multi-decadal variations were not persistent, decadal- and centennial-scale ENSO activity driven by solar forcing dominated Mesoamerican precipitation variability. Freshwater fluxes from the remnant Laurentide ice sheet into the Gulf of Mexico and the North Atlantic have additionally modulated the regional evaporation/precipitation balance. In particular, this study underlines the importance of solar activity on tropical and subtropical climate variability through forcing of the tropical Pacific, providing a plausible scenario for observed recurrent droughts on the decadal scale throughout the Holocene.

Reconstruction of Middle to Late Quaternary sea level using submerged speleothems from the northeastern Yucatán Peninsula

“…Interruptions of stalagmite growth are often associated with dry climatic conditions (Fairchild and Baker, 2012). Changes in the early Holocene precipitation amount have been documented for the Yucatán Peninsula and the western tropical Atlantic region and interpreted to be related to North Atlantic climatic oscillations (Hillesheim et al ., 2005; Bernal et al ., 2011; Fensterer et al ., 2013; Warken et al ., 2021). On centennial to millennial timescales, the so‐called Bond events, basin‐wide cold relapses in the North Atlantic, are recorded by fluctuations in the abundance of hematite‐stained, ice‐rafted grains and occurred at a recurrence rate of ~1500 years (Bond et al ., 2001).…”

“…This observation is counterintuitive to the common interpretation that speleothem growth phases are associated with more humid phases. The high resolution proxy record of speleothem NAH14 suggests that the early Holocene climate on the northern Yucatán Peninsula was characterised by a much more variable climate, which cannot solely be attributed to Bond events (Warken et al ., 2021). In their study, pronounced swings between dry and wet conditions on the decadal to centennial scale were identified.…”

The impact of seasonal and event‐based infiltration on transition metals (Cu, Ni, Co) in tropical cave drip water

“…In general, the isotopic composition of the drip water represents the long‐term infiltration‐weighted mean of the δ 18 O composition in precipitation 14,40 . Similarly, no significant seasonal variations were detected in the trace elemental ratios of Mg/Ca or Sr/Ca of the drip waters, which are often interpreted as hydrological proxies in speleothems 31,42–44 . Calcite precipitation rates respond to variations in both cave air pCO 2 and the Ca concentration of the drip water and are usually highest during the winter months when cave air pCO 2 is low 39,45 …”

“…The expected high Ca matrix in the reference materials and drip water samples may lead to significant interferences with Ca oxide molecules on masses 58u, 59u, and 60u, that is, the isotopologues 42 Ca 16 OH on mass 61u or 48 Ca 16 OH on mass 65u, respectively. An alternative explanation may be an additional mass bias in the interface or the collision cell.…”

“…Table 1 shows the typical instrumental parameters and method settings used for the analyses. In all sequences, count rates for the isotope masses 42 Ca, 43 Ca, 44 Ca, 58 Ni, 59 Co, 60 Ni, 61 Ni, 62 Ni, 63 Cu, and 65…”