Ecosystem Responses to Abrupt Climatic and Environmental Change in Southern Siberia during the Late Quaternary

• Main Author: Harding, Poppy Rebekah
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: UCL (University College London) 2019
• Subjects: permafrost; Siberia
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10072100/1/Harding_0000_Thesis_redacted.pdf; https://discovery.ucl.ac.uk/id/eprint/10072100/

The Late Quaternary documents climatic changes over a number of timescales. These are well studied in many regions, including Northern Europe, but much less so in some critical areas. One such region is continental southern Siberia, which is highly sensitive to modern climate changes. Palaeoenvironmental reconstructions are essential to provide context for these changes, and to examine regional sensitivity to climate forcing, however studies in Siberia are limited and good records of the last 30 ka BP, an important period for studying climatic changes, are rare. This thesis reconstructs the palaeoenvironment of Lake Baunt (55°11’15” N, 113°01’45” E), a site situated at the southern limits of Siberian permafrost, over the Late Quaternary (~30-6 ka BP). The reconstruction is based on a high-resolution diatom study from a record with excellent preservation, combined with organic geochemistry, and  18Odiatom/ 13Cdiatom, for the LGIT and Early Holocene, and supporting data, integrated through Bayesian age modelling. Baunt records the LGM, Heinrich events 1 and 2, the Lateglacial Interstadial, Younger Dryas, and Holocene fluctuations, shown through changes in ecosystem productivity, carbon cycling and hydrology. This highlights Baunt’s sensitivity to extrinsic climate forcing. Internal forcing’s have also been important factors, with local glacier melt influencing the record. Comparisons to regional and key Northern Hemisphere sites, along with climate models, has added to the understanding of the expression of these events in Southern Siberia. In particular, this work has shown that there is a complex response to Heinrich events, and also confirms suggestions of a link between AMOC and Siberian climate in the Early Holocene. This work highlights the sensitivity of southern Siberia to past climatic forcing and shows the need for more work in both this lake, and other sites within the region, to further understanding of how palaeoclimatic change influences regions remote from oceanic influences.