MS Thesis Defense


Carolyn Shull

August 15, 2019


Two Potential Climate Proxies: Investigating 100-year, high-resolution isotope records from speleothems along with phenological records, Midlands, United Kingdom

Climate and land use are changing, evidenced by instrument temperature records, historical maps and proxies such as tree rings and phenology records. One of several established sources of preserved data used for paleo-environmental reconstruction are cave speleothems. Information regarding surface environmental conditions and overlying land use can be recorded in the oxygen and carbon isotopes of speleothems. For this study, another potential record of climate was investigated, namely speleothems in the tunnels of the Birmingham Canal Navigations in West Midlands, United Kingdom. Tunnel speleothems were collected and the oxygen and carbon isotope delta values of their layers were analyzed. Local rain and tunnel waters were collected and the hydrogen and oxygen isotopes were analyzed. Isotope data from meteoric events was used to create a local mean water line (LMWL). Phenology data was also analyzed. From the speleothem samples, carbon isotopes are correlated to land use changes, while oxygen isotopes reflect the Atlantic Multidecadal Oscillation (AMO) and land use changes. Multiple species demonstrated progressively earlier phenology. The results indicate speleothems from canal tunnels in central England provide a record of land use changes from speleothems and could assist in monitoring changes in local land cover and the associated impact on area hydrology. In addition, speleothems provide a record of precipitation that reflects the AMO. The LMWL and the speleothem isotope data can serve as valuable datasets for climate modeling, especially with the recent focus on teleconnections. Local phenology records offer evidence of climate change in the region as well.