Inconsistent results should not be overlooked: A reply to Brooks et al. (2012)

Abstract

Empirical data in the form of many chironomid-based temperature reconstructions give an excellent opportunity to assess the chironomid approach to temperature reconstruction by testing its reproducibility. Brooks et al. ( The Holocene 22(12) 2012 (this issue)) offer a critique of points discussed in Velle et al. ( The Holocene 20 (2010) 989–1002), but fail to explain the poor reproducibility found when Holocene chironomid-based temperature reconstructions are compared. We discuss the issues raised by Brooks et al. (2012) and cite studies that demonstrate the complexity involved. We are grateful to Brooks et al. (2012) for contributing to the discussion. However, they overly rely uncritically on transfer functions and the resulting reconstructions as representatives of true patterns in nature. A major source of bias involved when chironomids are used as a palaeoenvironmental proxy is the response to confounding gradients. Many of the challenges discussed in the Forum Article, in the comment, and in the reply are also valid for other research fields within palaeoecology. The challenges should still be properly addressed in chironomid research.