The whole can of larvae opened up by the flawed University of Colorado study turned press release keeps getting squirmier. The study, led by Yarrow Axford studies midge larvae in sediment cores from Baffin Island to reconstruct temperature for the past and claims that “The past few decades have been unique in the past 200,000 years in terms of the changes we see in the biology and chemistry recorded in the cores,” and “We see clear evidence for warming in one of the most remote places on Earth at a time when the Arctic should be cooling because of natural processes.”
As I’ve pointed out on WUWT several times, the study is terribly flawed, because they haven’t considered other possible factors, such as DDT and other pesticides being transported into the lake from nearby military outposts and settlements, plus the tendency for transport or organotoxins into glacial ice which ends up in meltwater lakes. Plus the nearby weather station shows no significant warming.
WUWT reader “Ecotretas” points out this July 2009 peer reviewed study Evidence for a warmer period during the 12th and 13th centuries AD from
chironomid assemblages in Southampton Island, Nunavut, Canada by Nicholas Rolland et al, which uses the same techniques, but just one island west of Baffin:
The Rolland et al study temperature reconstruction shows a significantly different result than that of Axford:
A similar sort of reconstruction was done in alpine lakes of the Alps with similar results.
Here’s the Abstract of the Rolland et al study:
This study presents the Late-Holocene evolution of a northern Southampton Island (Nunavut, Canada) lake, using fossil chironomids supported by sedimentological evidences (XRF, grain size and CNS). All proxies revealed a relatively stable environment during the last millennium with short-lived events driving changes in the entire lake ecosystem. The chironomid-based paleotemperatures revealed variations of significant amplitude coincident with changes in the sediment density and chemical composition of the core. Higher temperature intervals were generally correlated to lower sediment density with higher chironomid concentration and diversity. Higher temperatures were recorded from cal yr AD 1160 to AD 1360, which may correspond to the Medieval Warm Period. Between cal yr AD 1360 and AD 1700, lower temperatures were probably related to a Little Ice Age event. This study presents new information on the timing of known climatic events which will refine our knowledge of the paleoclimate and climatic models of the Foxe Basin region. It also provides a new framework for the evolution of such freshwater ecosystems under the “Anthropocene” and underlines the importance of including sedimentological proxies when interpreting chironomid remains as this combined approach provides an extended overview of the past hydrological and geochemical changes and their impacts on lake biota.
Conclusions and perspectives
The paleolimnological study of this northern Southampton Island lake provides information and extends the spatial understanding of Northern Hemisphere climatic events (Medieval Warm Period and Little Ice Age) in the Foxe Basin region. Both chironomid-based August air temperature inferences and sedimentological assemblages suggest that Southampton Island was affected by a regional warming between cal yr AD 1160–1360 and a regional cooling between cal yr AD 1360– 1700. These results compare well with both archaeological studies made on Southampton Island and paleoclimatic studies conducted on the southern part of Baffin Island. In the present study, the information extracted based on the biological indicators (chironomids) was supported by a large range of sedimentological analyses. Such results confirm the importance of including sedimentological proxies when interpreting chironomid analysis as they provided an extended overview of the past hydrological and geochemical status of the lake which has affected its biological community. The large number of lakes covering the arctic landscape provides a real opportunity to improve our knowledge of past natural climates in still poorly studied arctic regions and develop new frameworks for the evolution of such freshwater ecosystems under the now called “Anthropocene.”
The entire paper is available online here (PDF).