Multi-proxy reconstruction of climate variability during the last 250 ka using precisely dated speleothems from south-eastern Spain.

• Applicant: Regina Mertz, Ph.D.
• Subject Area: Palaeontology ; Mineralogy, Petrology and Geochemistry ; Atmospheric Science
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 290435864

The objective of this proposal is the reconstruction of terrestrial climate variability in south-eastern Spain during the last 250 ka using speleothems. South-eastern Spain is one of the driest regions in southern Europe. According to the last IPCC report, currently arid regions will suffer from an increasing frequency and duration of warm spells and heat waves as well as increasing intensity and duration of droughts. These changes go along with substantial risks for both the environment and economy. Investigation of terrestrial paleoclimate records from currently arid areas is, thus, of great importance.Due to the dry conditions, climate archives from south-eastern Spain are highly sensitive to even subtle changes in precipitation. However, information from terrestrial climate archives in southern Iberia is limited and mostly restricted to pollen and sediment sequences, which have a relatively low temporal resolution and are difficult to date beyond the range of radiocarbon dating. Well-dated speleothem climate proxy records are currently mainly restricted to the northern part of Spain, which is, however, characterized by relatively high humidity and mild temperatures.We will reconstruct past climate variability at high temporal resolution from a precisely dated flowstone sequence at Cueva Victoria, south-eastern Spain, which is well known for its spectacular Pleistocene fauna. We will focus on the last 250 ka, which are contained in several drill cores. For this period, a precisely dated, high-resolution terrestrial record from south-eastern Spain is not available yet.Preliminary data show that flowstone growth at Cueva Victoria is highly sensitive to past changes in precipitation and that flowstone growth phases are related to past global warm phases. Precise dating by the 230Th/U-method will thus enable us to determine the timing and duration of Marine Isotope Stages 1, 3, 5 and 7 as well as the corresponding sub-stages in terrestrial south-eastern Spain. Furthermore, we will generate multi-proxy records consisting of high-resolution stable isotope and trace element profiles for the corresponding growth phases. This will enable a robust interpretation of the proxy signals in terms of past climate variability. The high sensitivity of the proxy signals observed in the preliminary data set emphasizes the large potential of this unique paleoclimate archive for the last ca. 250 ka in south-eastern Spain.Part of this material was already in the focus of a previous DFG proposal by the applicant, but was unfortunately rejected. The main criticism of the reviewers was that the preliminary work was insufficient. However, they highlighted the general potential of the project. Following their constructive comments, I established new collaborations and generated additional age and climate proxy data to proof that the samples are a very promising paleoclimate archive, which can be accurately dated.

• DFG Programme: Research Grants