This dataset provides counts of chironomid head capsules for the MIS 5cd sediment sequence retrieved from Sokli (Finland) in 2002. Counts per taxon are presented against depth (m). The chironomid dataset provides information on Early Weichselian lake and fluvial (floodplain, stream channel) ecosystem dynamics and was used to quantitatively reconstruct climate conditions (Engels et al., 2010). A total of 76 samples from the MIS 5cd sediment sequence were selected for chironomid analysis, with a higher number of samples taken from the central part of the sequence, where chironomid concentrations were low. The samples were treated with warm KOH (10%) to de-flocculate the material and subsequently rinsed through a sieve with a 100-µm mesh. The samples in the interval between 16.08 and 16.73m did not disintegrate completely after treatment with KOH, and, after trying a variety of approaches, an additional overnight treatment with cold HF was added to the preparation procedure. Chironomid head capsules (HCs) were hand-picked from the residue using a Bogorov sorting tray and mounted on permanent microscope slides using Euparal mounting medium. HCs were identified using Brooks et al. (2007). Where the sum of head capsules was below 50, neighbouring samples have been amalgamated to ensure a representative count sum was reached. The lowermost sample of the sequence contains 47 HCs but was not merged with a neighbouring sample due to the differences in the assemblage composition. The final dataset presented here contains 47 samples. All analyses were performed in the laboratories of Stockholm University, Sweden.

The funding was provided by Swedish Nuclear Fuel and Waste Management Company (SKB) and Bolin Centre for Climate Research (Stockholm University).