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A 300-Year Multi-Proxy Hydro-Ecological Record from Spruce Island Lake, Canada
Reference
Wolfe, B.B., Karst-Riddoch, T.L., Vardy, S.R., Falcone, M.D., Hall, R.I. and Edwards, T.W.D.  2005.  Impacts of climate and river flooding on the hydro-ecology of a floodplain basin, Peace-Athabasca Delta, Canada since A.D. 1700.  Quaternary Research 64: 147-162.

What was done
Spruce Island Lake (5851'N, 11129'W) is a shallow, isolated, upland lake in a bedrock basin located in the northern Peace sector of the Peace-Athabasca Delta in northern Alberta, Canada.  In the present study, the authors conducted a multi-proxy hydro-ecological analysis of the lake in an attempt to assess the impacts of both natural variability and anthropogenic change on the hydro-ecology of the region over the past 300 years. Specifically, their research was designed to answer the following three questions: (1) Have hydro-ecological conditions in Spruce Island Lake since 1968 (the year in which river flow became regulated from hydroelectric power generation at the headwaters of the Peace River) varied beyond the range of natural variation of the past 300 years? (2) Is there evidence that flow regulation of the Peace River has caused significant changes in hydro-ecological conditions in Spruce Island Lake? (3) How is hydro-ecological variability at Spruce Island Lake related to natural climatic variability and Peace River flood history?

What was learned
Wolfe et al.'s research efforts revealed that hydro-ecological conditions varied substantially over the past 300 years, especially in terms of multi-decadal dry and wet periods.  With respect to the three research questions posed above, for example, the authors found for question #1 that hydro-ecological conditions after 1968 have remained well within the broad range of natural variability observed over the past 300 years, with both "markedly wetter and drier conditions compared to recent decades" having occurred prior to the time of Peace River flow regulation.  With respect to question #2, they note that the current drying trend is not the product of Peace River flow regulation, but rather the product of an extended drying period that was initiated in the early to mid-1900s.  Lastly, with respect to question #3, Wolfe et al. showed that the multi-proxy hydro-ecological variables they analyzed were well correlated with other reconstructed records of natural climate variability, indicating a likely climatic influence on Spruce Island Lake hydro-ecological conditions over the period of record.

What it means
It is important to note that there is nothing unusual about recent trends in the hydro-ecology of the Spruce Island Lake region.  Wet and dry conditions of today fall well within the range of natural variability and show no fingerprint of anthropogenic global warming.  What is more, they even bear no fingerprint of anthropogenic flow control on the Peace River since 1968, demonstrating, in the words of the authors, that "profound changes in hydro-ecological conditions are clearly a natural feature of this ecosystem, independent of human influence or intervention."

Reviewed 21 December 2005