Chironomid-inferred summer temperature and lake development during the last interglacial-glacial cycle in central Europe

The last interglacial-glacial cycle represents an interval in which a broad range of climatic conditions
forced landscape and ecosystem development in central Europe, and to date there is a sparsity of
long, millennial scale, continuous palaeoclimatic records from the region. Palaeoclimatic
reconstructions are essential to develop our understanding of how climatic forcing from internal and
external variables, as well as associated climatic feedbacks, produced those landscape and ecosystem
developments. This thesis aims to develop new mean July air temperature records covering large
sections of the last interglacial-glacial cycle from central Europe in the pursuit of better understanding
past climate development and climatic forcing by utilising the biotic proxy Chironomidae. Using
sediment records from Burgäschisee, Swiss plateau, and Füramoos, southern Germany, records of
chironomid assemblage change were developed, used to assess changes in the lake ecosystems and
environments, and then implemented in a transfer function to quantitatively estimate change in July
air temperature. For the Füramoos record this was achieved for the interval from ca. 127 to 49 ka
while the Burgäschisee record covered the interval from ca. 18 to 14 ka. The chironomid assemblage
as well as other associated chitinous invertebrate remains were utilised to qualitatively assess changes
in temperature, nutrient state and organic content, and to a lesser extent changes in lake level. Further
analysis using a transfer function enabled the quantitative estimation of mean July air temperature
from the chironomid assemblages for the study intervals. The largest changes in mean July air
temperature were associated with changes in northern hemisphere July insolation and major
reorganisations of the local vegetation. These changes were at the mid to late Eemian transition at ca.
115–125 ka, the transition from MIS 5 to MIS 4 at ca. 84–76 ka. and the onset of the Bölling interstadial
at ca. 16–14 ka. Furthermore, Stadials A and B in the Würmian, which are characterized by forest
openings, were not found to be associated with major July air temperature changes and probably a
result of decreases in mean temperature of the coldest month or precipitation.