Unsatisfactory field data in a calibration model for inferring past temperatures from chironomid assemblages in northern Fennoscandia: a comment on Olander, Birks, Korhola and Blom

Olander et al. (1999) used single temperature measurements of surface water to represent mean July temperatures of lake waters in Lapland. It is empha sized that this is not an appropriate basis for calibration of temperatures indicated by chironomid assemblages and to draw conclusions about past air temperatures. Air temperatures at the study sites were estimated and calcu lated yet the role of variations in topography has been omitted. The parame ters used, such as lake depth, distance beyond tree-line and pH look good b ut are inaccurate and therefore problematic in statistical evaluations. The authors have not considered the role of the ice cover on the lakes.