Development of a globally applicable palaeothermometry method based on luminescence: Advances in method development and validation

Abstract

The scarcity of terrestrial temperature proxies has been a major challenge in the reconstruction of continental climate evolution throughout the Last Glacial Maximum (LGM) and the Pleistocene-Holocene transition. Understanding such extreme climatic conditions and major system shifts in Earth’s history is paramount for constraining climate sensitivity and predicting future climate evolution in the light of rising greenhouse gas concentrations.Our research aims to develop a globally applicable method for temperature sensing during this timescale using the low-temperature (i.e., 200–280 °C) thermoluminescence (TL) signal of near-surface bedrock feldspar which has been demonstrated to be sensitive to terrestrial surface air temperature fluctuations over geological timescales (Biswas et al., 2020). As such, palaeothermometry represents one of few available proxies for terrestrial temperature and can aid in quantifying the magnitude of rapid climate changes on a more local scale.While the theoretical feasibility of TL palaeothermometry has been demonstrated (Biswas et al., 2020), it still requires accurate validation on additional samples of well-constrained temperature history. Furthermore, the method has not yet been applied to a broad set of samples for temperature reconstruction purposes.Our contribution aims to close this knowledge gap by benchmarking recent methodological improvements against samples from borehole sites located in Germany and Japan. We further present first surface air temperature reconstructions at a number of study sites, which we intend to use to constrain the evolution of altitudinal and latitudinal temperature gradients since the LGM. We show that TL palaeothermometry can be used to retrieve accurate rock and surface air temperatures and may now be more routinely applied. ReferencesBiswas, R.H., Herman, F., King, G.E., Lehmann, B., Singhvi, A.K., 2020. Surface paleothermometry using low-temperature thermoluminescence of feldspar. Clim. Past 16, 2075-2093.