Geophysical Research Letters

Comment on “Abrupt environmental change in Canada's northernmost lake inferred from fossil diatom and pigment stratigraphy” by Dermot Antoniades et al.



[1] Antoniades et al. [2007; hereinafter referred to as A07] present an analysis of a 19-cm lake sediment core from Ward Hunt Island from northern Canada. They conclude that a significant and abrupt change in the aquatic communities occurred in this lake during the past 2 centuries that was unusual with respect to the previous 8ka. In the paper, and especially in quotes to the press (e.g.,;; the authors conclude that their results, along with those from Smol et al. [2005] provide evidence for amplification of climates with latitude due to human caused global warming, an event unique in the past 8 ka. However, there are a number of problems in these data and flaws in the author's interpretations that render their results questionable. Their conclusions do not hold up to scrutiny as they do not concord with other information we have about climate variability in the Arctic. I have four major comments on the data, and several on the interpretation.