Speleothems are valuable sources of information on past climate and rainfall variations. The Naharon sinkhole near Tulum on the Yucatán Peninsula, Mexico, hosted an early Holocene skeleton of a young female. It was found buried in fine grained sand in the today flooded cave. In a new study of a particular fast growing speleothems of this cave, a team of researchers led by Sophie Warken and Wolfgang Stinnesbeck from Heidelberg University, the Natural History Museum of Karlsruhe, Khalifa University Abu Dhabi, University Innsbruck, and the Museum “del Desierto”, Mexico now provide evidence on the climate of the early human settlers.
The results suggest that past changes of the suns activity are synchronous to the occurrence of droughts during the early Holocene c. 11,000 – 9,500 years ago. This period of time is part of the last big climate transition staring with the end of the Last Glacial. 11,000 years ago remnant ice sheets were still existing in the northern hemisphere and sea level was about 20 m lower than today. The origin of droughts is possibly due to a link of solar activity variations and the occurrence of El Nino southern oscillations.
Ultra-high precision age determination and geochemical element and isotope analysis of the speleothems composition advocate for the frequent occurrence of severe droughts on the northern Yucatán Peninsula. Hence, it is likely that the earliest people of Mesoamerica experienced the rising sea level as well as important climate instability.
The authors infer that moderate solar modulations as attested in the sun-spot cycles and radiocarbon residuals may have played a role in tropical Pacific warms and the subsequent development of El Nino events every couple of years. These events increased the probability of severe droughts on the Northern Yucatán peninsula during the early Holocene. Similar observations had already been made for the climate boundary conditions impacting the end of the Maya culture during the late Holocene, i.e. 7000 years later.
Hence, even the earliest settlers in Mesoamerica had to cope with variable freshwater supply and severe droughts. From a climate physics point of view, the results provide further evidence for a persistent influence of solar variability on the modulation of precipitation patterns in the tropics.
Publication: Warken, S. F., Schorndorf, N., Stinnesbeck, W., Hennhoefer, D., Stinnesbeck, S., Förstel, J., Steidle, S.D., Avilés Olguin, J., and Frank, N. 2021). Scientific Reports 11, 13885 https://doi.org/10.1038/s41598-021-93417-z
Photo Courtesy: Valentina Cucchiara, Jerónimo Avilés Olguin