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PDF, English - main document Download (68MB) | Lizenz: Statistical assessment and modeling of spatio-temporal patterns in speleothem records from the Last Glacial to present day by Bühler, Janica Carmen underlies the terms of Creative Commons Attribution-NoDerivatives 4.0

Abstract

Our understanding of past precipitation changes is still insufficient despite their relevance for future projections given anthropogenic warming. Here, we assess the potential and limitations of paleoclimate archives and simulations to record and resolve past hydroclimate changes on regional to global and interannual to orbital scales. We compare the abundance of heavy to light oxygen isotopes, routinely measured in speleothem records as water cycle tracers, to isotopic signatures simulated by isotope-enabled climate models. We show that a multi-model ensemble represents hydrological changes between the Last Glacial Maximum and Mid-Holocene more accurately than a single model alone. The comparison is hampered by limitations in both model and proxy data. Speleothem growth rates and oxygen isotope ratios can serve as proxies for precipitation amount in low- to mid-latitudes given sufficient temporal resolution and at timescales unaffected by karst damping. Spatial patterns of simulated oxygen isotope ratios show only small offsets compared to speleothem records for the last millennium. However, the analyzed models underestimate variability on multi-decadal to centennial timescales. Our study provides the basis for future research using proxy system models and additional paleoclimate records and simulations to further explore the mechanisms of simulated and archived changes of the past hydroclimate.