Evidence for a warmer period during the 12th and 13th centuries AD from chironomid assemblages in Southampton Island, Nunavut, Canada

Abstract

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.

Major postglacial summer temperature changes in the central coniferous boreal forest of Quebec (Canada) inferred using chironomid assemblages

“…Viau and Gajewski (2009) also recorded this warming period in northern Quebec. Rolland et al (2009) inferred a warming period between 1160 and 1360 AD on Southampton Island (Nunavut, Canada) based on chironomid assemblages. In the central Northwest Territories (Canada), chironomid-inferred temperature reconstructions have shown a warming which occurred between 1 and 0.7k cal a BP (Upiter et al, 2014).…”

Late Holocene paleoenvironmental changes in the southern Okinawa Trough inferred from a diatom record

“…The MWP was also found in the central Alps, Canada, Sweden, and other areas worldwide; however, the duration of the MWP in different areas varied. For instance, the MWP in the central Alps, Canada and Sweden occurred around 800-1300 AD, 1160-1360 AD, and 900-1150 AD, respectively [34][35][36]. Changes in the temperatures of the Northern Hemisphere over the last 1000 years reconstructed from tree-ring data suggest that the MWP occurred in many regions during the interval of 900-1300 AD [37].…”

Effect of removing small (<150 μm) chironomids on inferring temperature in cold lakes

“…To explore the potential of using chironomid assemblages containing only head capsules [150 lm in down-core studies of high latitude/altitude lakes, we measured the fraction of head capsules \150 lm in two lakes in Sweden (Lake Njulla, Lake 850), one lake in Switzerland (Lake Silvaplana), two lakes in Norway (Brurskardstjønn, and Vestre Øykjamyrtjørn) and two lakes in Canada (see Table 1 for lake details). For details on lake coring, sieving procedure, and the species assemblages from the Norwegian lakes, see Velle et al (2005), for the Swedish lakes see Larocque and Hall (2004), for the Swiss lake see Blass et al (2007), Bigler et al (2007), Larocque et al (2009) and for the Canadian lakes see Rolland et al (2009).…”