Coeval fluctuations of the Greenland ice sheet and a local glacier, central East Greenland, during late glacial and early Holocene time

Abstract

We present a 10Be chronology of late glacial to early Holocene fluctuations of a Greenland ice sheet outlet glacier and the adjacent Milne Land ice cap in central East Greenland. Ages of boulders on bedrock indicate that both ice masses receded during the Younger Dryas (YD), likely due to rising summer temperatures. Since Greenland ice core records register cold mean annual temperatures throughout the YD, these ice‐marginal data support climate conditions characterized by strong seasonality. The ice sheet outlet glacier and ice cap deposited inner Milne Land Stade moraines at 11.4 ± 0.8 ka and 11.4 ± 0.6 ka, respectively (mean moraine ages and 1σ uncertainties). Based on the coeval moraine ages, we suggest that both ice masses responded to climate conditions acting on the ice margins, specifically ablation. Moreover, the ice sheet responded sensitively (i.e., on the same time scale as a small ice cap) to climate conditions.

Greenland‐Wide Seasonal Temperatures During the Last Deglaciation

“…An east Greenland valley glacier moraine sequence in the Scoresby Sund area suggests a Younger Dryas (YD) summer time cooling of only 4-6 ∘ C relative to present (Broecker, 2006;Denton et al, 2005;Kelly et al, 2008;Levy et al, 2016), much smaller than the mean annual cooling of around 15 ∘ C (Severinghaus et al, 1998). These estimates are in good agreement with our merged product, which suggests about 4.4 ∘ C JJA cooling during the YD at Scoresby Sund (Figure 3e, white square).…”

“…Its past extent is recorded in glacial landforms such as moraines (e.g., Denton et al, 2005;Funder et al, 2011;Kelly et al, 2008;Levy et al, 2016;Rinterknecht et al, 2014;Young et al, 2013) and most precisely reconstructed using exposure dating techniques (e.g., Carlson et al, 2014;Corbett et al, 2011;Hughes et al, 2012;Kelley et al, 2013;Larsen et al, 2014;Sinclair et al, 2016;Young et al, 2013). Its past extent is recorded in glacial landforms such as moraines (e.g., Denton et al, 2005;Funder et al, 2011;Kelly et al, 2008;Levy et al, 2016;Rinterknecht et al, 2014;Young et al, 2013) and most precisely reconstructed using exposure dating techniques (e.g., Carlson et al, 2014;Corbett et al, 2011;Hughes et al, 2012;Kelley et al, 2013;Larsen et al, 2014;Sinclair et al, 2016;Young et al, 2013).…”

“…The last deglaciation (19-7 ka BP) presents a natural experiment in which to assess the sensitivity of the GIS. Its past extent is recorded in glacial landforms such as moraines (e.g., Denton et al, 2005;Funder et al, 2011;Kelly et al, 2008;Levy et al, 2016;Rinterknecht et al, 2014;Young et al, 2013) and most precisely reconstructed using exposure dating techniques (e.g., Carlson et al, 2014;Corbett et al, 2011;Hughes et al, 2012;Kelley et al, 2013;Larsen et al, 2014;Sinclair et al, 2016;Young et al, 2013). Simultaneously, the (annual mean) temperature evolution can be reconstructed precisely from Greenland ice cores (Grootes et al, 1993;NGRIP community members, 2004;NEEM community members, 2013), allowing ice sheet modeling of the deglaciation in Greenland Simpson et al, 2009;Tarasov & Richard Peltier, 2002).…”

A 10Be chronology of early Holocene local glacier moraines in central West Greenland

“…; Levy et al . ). In order to accurately compare 10 Be ages between studies, we calculate all 10 Be ages using a local production rate for the Arctic (Young et al .…”

“…; Levy et al . ). There is increasing evidence that additional early Holocene abrupt climate events occurred (e.g.…”