Lake archives in Canada and Alaska: Do we see effects of polar climate change during the Early Holocene?

• Main Authors: Lenz, Josefine, Fritz, Michael, Wetterich, Sebastian, Schirrmeister, Lutz, Lantuit, Hugues, Pollard, Wayne
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Climate change; Herschel; Herschel Island; Ice; permafrost; Thermokarst; Alaska; Yukon
• Online Access: https://epic.awi.de/id/eprint/30363/; https://hdl.handle.net/10013/epic.39312

Terrestrial deposits provide valuable information about past landscape development in the Arctic. Especially lake sediments as continuous records are highly important to comprehend the post-glacial dynamic of the periglacial environment in northern Canada and Alaska. It is crucial to evaluate already studied and published paleoenvironmental archives as well as to fill gaps of knowledge to gain a better understanding of the past, present and future polar climate change. Various literary sources were studied to get an overall picture of climate records in the North American Arctic. Since environmental archives are relatively rare in the western Canadian Arctic a lake sediment record from Herschel Island (Yukon Territory) was analyzed as a case study using radio carbon age determination and several sedimentological and geochemical methods. Many authors draw the conclusion that a progressive amelioration of climate conditions with warmer-than-modern levels of air temperatures was reached during the period of 11,000 to 8,500 cal. a BP in the western Canadian Arctic and Alaska (e.g. Szeicz and MacDonald 2001, Bigelow and Edwards 2001). Also Herschel Island’s lake archive demonstrate an early Holocene warming by about 10,300 to 8,800 cal. a BP: variations in nitrogen, total organic carbon content and stable carbon isotopes indicate the lake onset by pooling of water and thaw subsidence of the ice-rich permafrost. The Pleistocene-Holocene transition was a period of dramatic and rapid environmental changes, particularly at coastal sites. The formation of thermokarst lakes in permafrost regions was extremely intense during the Holocene Thermal Maximum (HTM). On the coastal plain in the western Canadian Arctic thermokarst lakes developed especially between 11,600 and 10,300 a BP (Rampton 1988) – so did the lake on Herschel Island in all likelihood. According to Kaufman et al. (2004) the HTM was time-transgressive, which means the western Canadian Arctic warmed earlier (11,300+/-1,500 a BP) than northern continental Canada ...