Analysis of Loch Lomond Stadial climate dynamics using taxon-specific δ18Ochitin records

The Atlantic Meridional Overturning Circulation (AMOC) is currently in its weakest state compared to the last 1000 yr (Caesar et al., 2021) due to anthropogenic climate change. It is unknown how further weakening or shutdown of AMOC will impact the European climate system, but such understanding will be of utmost importance to effectively adapt to emerging conditions. The Loch Lomond Stadial (LLS; 12,800-11,650 cal yr BP) represents the last time in climate history when there was a prolonged weakening of AMOC (Renssen et al., 2015; Mangerud, 2021) and provides an ideal test case for understanding the impact of AMOC weakening on European climate. Whilst there is clear evidence of a time-transgressive mid-LLS climate shift (Lane et al., 2013), a recent high-resolution study from Old Buckenham Mere (Norfolk, East England) suggests that this climate shift is more complex than initially thought (tripartite rather than a bipartite structure; Francis, 2022). Due to the low sampling resolution of many available Late-glacial palaeoclimate records from the UK, it is unclear if such a tripartite structure could be identified at other sites as well and there is a need to expand high-resolution oxygen-isotope reconstructions.
The first aim of this proposal is to determine to what extent the δ18Ochitin signatures of a range of chironomid taxa present in Lake Llangorse are driven by ambient temperature to identify which species to focus on. The second aim of this proposal is to analyse LLS climate dynamics using these taxa. We will determine the amplitude of change at the onset and end of the LLS at Llangorse based on taxon-specific δ18Ochitin records (aim 2a) and determine whether the LLS is characterized by a tripartite climate signal as recently observed (aim 2b).