What drives the peat-based palaeoclimate record? A critical test using multi-proxy climate records from northern Britain

Peatland palaeoclimate sequences produce bog surface wetness (BSW) reconstructions which are commonly interpreted as changes in summer effective precipitation, i.e. the net balance between precipitation and evapotranspiration, the latter being mainly governed by temperature. The relative roles of precipitation and temperature have been investigated previously, although over centennial and millennial timescales no conclusive relationships have as yet been established, but it has been suggested that summer temperature may play the dominant role. We aimed to test this by comparing a late-Holocene peat-based palaeoclimate record from Walton Moss, northern England, with a chironomid-inferred temperature (CI-T) reconstruction from a nearby lake, Talkin Tarn. Both records showed significant changes in inferred climate over the last 3000 years with lower temperatures corresponding to increases in BSW. The CI-T reconstruction, which covered the last 6000 years, was also compared to a longer BSW record, again from Walton Moss, and the same relationships were observed. Our evidence therefore suggests that over centennial timescales summer temperatures are important drivers of the peat-based palaeoclimate record.