Novel proxies of the Holocene climate variability in stalagmites in Slovenia

While models of global climate change focus mostly on climate itself, the solution to the humanity to adapt or prevent its consequences requires knowledge on how the landscape will respond when cooling or warming events occur. In light of predicted modern raise of global temperature, in particular at times when the climate seems to be close to the tipping point, the interdisciplinary analysis of paleoclimate and its environmental implications is as pertinent as ever. This applies not only for the prediction of the climate development in the future, but also on predicted change of local environments, ecology and, last but not least, human civilization. In the absence of instrumental or historic written records from the past, natural archives and contained proxies are used to reconstruct not only the temperature in the past, but also general environmental features, such as amount and distribution of precipitation and vegetation cover. Given the abundance and distribution of karst caves, the use of stalagmites for reconstruction of climate conditions in Slovenia seems to be obvious. Namely, because of virtually stable temperature and atmospheric conditions in caves, stalagmites shall provide an undisturbed and interconnected timeline of past environmental change. Records of contained climate proxies (δ O, δ C, mineral and elemental composition, and thickness of laminae which respond to the ambient temperature, amount, chemical and isotopic composition of drip water, precipitation rate etc.) allow to predict how the climate, landscape and ecosystems change with time.

The aim of the study is to elucidate the climate and environmental conditions in Slovenian territory during Holocene, focusing on the 8.2, 4.2 and 2.8 ky events, which are poorly or not at all documented in this region. Isotopic and geochemical records in a stalagmite from Slovenia will be analysed using advanced analytical techniques for high resolution profiling. Analyses will be performed in collaboration with partner research institutions from Australia, Germany and France. The obtained records will be compared to existing paleoclimate profiles derived from stalagmites and other archives and proxies (aquatic sediments, peat) in the region and will provide information on how the environment in southern part of Slovenia reacted to climate change in periods of cyclic and rapid temperature fluctuations in Holocene (e.g. 8.2 ky event), events around the beginning of Meghalayan age (around 4.2 ky ago) and later until the beginning of the Common Era.

Since unequivocal relationships of speleothem instrumental records with paleoclimate parameters have only rarely been attained, ample attention will be paid to the analysis of temporal trends in distribution and isotopic composition of local precipitation and drip water at both sites. So we will determine how the δ O signal of precipitation is modulated by karst processes from infiltrated rain to the speleothem and how the temperature (δ O) and environmental (δ C, microstructure, detrital fraction) proxies relate to the external climate parameters, and whether the δ O of speleothem is truly recording the ambient temperature variation and how it reflects the precipitation amount, which would be important to trace dry periods (e.g. 4.2 ky and 2.8 ky events).