An archive of many hats: speleothems for coupled climate and ecosystem reconstructions

Speleothems are secondary cave carbonate deposits and an established terrestrial paleoclimate archive. Moreover, they have the potential to record conditions in the ecosystem overlying the cave, particularly the vegetation and soil. Coupled records of paleoclimate and -ecological information from a single speleothem would be an invaluable source of information to understand the past and future sensitivity of terrestrial ecosystems to climate change, particularly under the lens of anthropogenic forcing. In order to develop proxies that record unambiguous and quantifiable ecosystem processes, it is necessary to i) understand and characterize how processes in the soil-karst-cave system will affect geochemical tracers that may be sensitive to ecosystem conditions, and ii) develop transfer functions and frameworks that allow the interpretation of such tracers in speleothems over time periods longer than observations. In this talk, I will discuss ways to approach these problems using different methods. I will show how combining multiple proxy measurements and forward modeling can be used to quantify the temperature sensitivity of soil respiration in the past from speleothem δ13C records. Finally, I will discuss the potential of speleothem organic carbon isotopes (δ13C and 14C) as direct tracers for surface ecosystem conditions, and the challenges and opportunities associated with these measurements.