Lacustrine oxygen-isotopes as tracers of past climate change in NW Europe.

Past Life and Environments

UCL

RHUL

Simon Blockley (RHUL),

The Holocene (last ~11,700 years BP) has experienced multiple abrupt climatic events. However, their often subtle expression in the palaeo-record results in many proxies lacking the sensitivity to identify them. The use of oxygen isotopes to investigate palaeotemperature of major abrupt events in cold stages, particularly ice core records, is well-established. In contrast, their use on Holocene lake sediments is limited, despite their potential to also allow for palaeoprecipitation and palaeoatmospheric reconstruction of these subtler abrupt climatic events when high-resolution sampling Is aligned with a good chronology. These reconstructions are made possible by the predictable relationship between water isotope ratio and air temperature. Unusually, large shifts may be attributed to other forcing factors such as precipitation; the δ18O composition of precipitation being strongly controlled by atmospheric processes. This project uses this theory to build on the work of Holmes et al. (2010) to investigate the palaeoclimatic record from lacustrine sediments at various Holocene time slices and the comparison with modern lake water isotope systematics and outputs from an isotope-enabled general circulation model (GCM) outputs.

The outcomes of this research will be of interest to climatologists concerned with atmospheric circulation changes and palaeolimnologists interested in the interpretation of shallow-lake carbonate isotope records.
The research will further our understanding of climate evolution during the Holocene and mechanisms that drive abrupt climatic events. This will contribute to our ability to model, predict and prepare for potential events in the light of modern climate change in NW Europe. The comparison with archaeological evidence where appropriate may indicate societal response to change. Finally, the development of tephrochronologies at the selected field sites have the potential to a) identify tephra at some of the most southernly site in Britain to date, b) identify new Holocene tephras, c) demonstrate that tephra is a viable chronological alternative in late Holocene sites which can circumvent existing issues associated with radiocarbon, 210Pb and SCP dating methodologies which are presently widely used.

Melanie Leng (BGS)
David Sear (University of Southampton)
Louise Sime (BAS)

• NIGL Grant-in-Kind for Stable Isotope Work – NERC Stable Isotope Facility (BGS)
• NIGL Grant-in-Kind for Stable Isotope Work – NERC Stable Isotope Facility (BGS)
• Access and Widening Participation Summer Challenge Award – UCL
• INQUA 2019 Travel Fund – QRA

• Joanna Tindall (2020) How Can We Use Oxygen Isotopes from Ostracods to Reconstruct Abrupt Climate Changes from the Holocene?