Late Quaternary paleoclimate of western Alaska inferred from fossil chironomids and its relation to vegetation histories

The last deglaciation of Alaska

“…Pendleton et al (2015) suggested that early deglaciation in the Brooks Range may have also been related to the impact that the expanded Laurentide Ice Sheet had on atmospheric circulation. Indeed, simulations by global climate models show that the Laurentide Ice Sheet caused significant warming and drying in the Alaska-Yukon region during the LGM (Roe and Lindzen, 2001;Otto-Bliesner et al, 2006), which agrees with very little LGM temperature depressions based on chironomids (Kurek et al, 2009) and pollen (Bartlein et al, 2011). Regardless, among the eight sites in Alaska reviewed here that have sufficient existing chronology to address this question, data from seven sites support significant glacier recession prior to ~18 ka.…”

“…This flooding event may have led to regional forcing, such as an increase in precipitation due to more northerly storm tracks (Kaufman et al, 2010) that may have influenced glacier mass balance. Of course, there could have been more glacier fluctuations during the Younger Dryas than are currently recognized because they may have occurred during a climate state that was warmer than the late Holocene (e.g., Kurek et al, 2009;Kaufman et al, 2016), and hence moraines were later obscured by subsequent glacier advances during the Holocene.…”

Global climate evolution during the last deglaciation

“…During the LGM, proxy records indicate that July temperatures were approximately 4°C lower than present in eastern Beringia (62), whereas central and western Beringia experienced relatively warm summers similar to present (63). Summer temperatures in eastern Beringia began to increase between 17 and 15 ka, with peak warmth reached by the start of the Bølling, and temperatures similar to or warmer than modern during the subsequent Allerød (63).…”

“…During the LGM, proxy records indicate that July temperatures were approximately 4°C lower than present in eastern Beringia (62), whereas central and western Beringia experienced relatively warm summers similar to present (63). Summer temperatures in eastern Beringia began to increase between 17 and 15 ka, with peak warmth reached by the start of the Bølling, and temperatures similar to or warmer than modern during the subsequent Allerød (63). During the Younger Dryas, temperatures were similar or warmer-than-present across most of central Alaska, northeastern Siberia, and possibly the Russian Far East and northern Alaska, whereas southern Alaska, eastern Siberia, and portions of northeastern Siberia cooled (64).…”

Influence of water availability in the distributions of branched glycerol dialkyl glycerol tetraether in soils of the Iberian Peninsula

“…However, the reconstruction of continental temperature is particularly challenging as there are few quantitative proxies. There are a number of studies that have used microfossil assemblages based on pollen, diatoms or chironomids preserved in lake sediments to estimate past air or lake water temperatures (e.g., Colinvaux et al, 1996;Lotter et al, 1997;Kurek et al, 2009). A molecular proxy initially developed to estimate past sea surface temperatures has also been shown to be applicable in lake settings, i.e., the long-chain alkenone unsaturation index (e.g., Marlowe et al, 1984;Zink et al, 2001;Toney et al, 2010).…”