<![CDATA[By Kenneth Richard
Newly published science indicates glaciers in the High Arctic Svalbard/Barents Sea region have rapidly advanced in the last decade — surging 16 kilometers since 2008, which is the greatest ice growth since 1890.
About 8,000 to 10,000 years ago, this region was 6°C warmer than today. Consequently, the region’s glaciers were much smaller (or non-existent) at that time and the sea ice was much less extensive (0-10% spring sea ice vs. today’s 80%).
“Most large tidewater glaciers in Svalbard are known to have surged at least once in the last few hundred years. However, very little information exists on the frequency, timing or magnitude of surges prior to the Little Ice Age (LIA) maximum in ∼1900. We investigate the sediment-landform assemblages produced by multiple advances of the Nathorstbreen glacier system (NGS) in order to reconstruct its Late Holocene surge history. The glacier has recently undergone one of the largest surges ever observed in Svalbard, advancing ∼16 km from 2008 to 2016.”
“By combining these data with previous marine geological investigations in inner and outer Van Keulenfjorden, we demonstrate that NGS [Nathorstbreen glacier system] has advanced at least four times prior to the recent 2008–2016 surge: twice at ∼2.7 kyr BP, at ∼1160 AD, and in ∼1890. This represents a unique record of the timing and magnitude of Late Holocene tidewater glacier surges in Svalbard.”
“Reconstructing Holocene Glacier and Climate Fluctuations From Lake Sediments in Vårfluesjøen, Northern Spitsbergen … Here, we present work from the northern coast of Spitsbergen in which we unravel the sediment sequence from a distal glacier-fed lake, Vårfluesjøen. … During the early Holocene, the glaciers in the Vårfluesjøen catchment were considerably smaller than today or had even melted completely. … D’Andrea et al. (2012) […] point to increased heat transport via the West Spitsbergen Current, and accompanying increased winter precipitation, rather than cold temperatures, to have caused LIA expansions on Svalbard.”
“During the early and mid-Holocene period, other glacier reconstructions from the west coast of Svalbard suggests that many glaciers were small or completely melted during this time interval (Svendsen and Mangerud, 1997; Røthe et al., 2015; van der Bilt et al., 2015; de Wet et al., 2018). Mangerud and Svendsen (2018) postulated that August temperatures in Svalbard were 6°C warmer from 10000 to 9000 cal. yr. BP than they are today, based on the presence of Zirfaea crispate.”
“About 60% of Svalbard is covered by glaciers today, but many of these glaciers were much reduced in size or gone in the Early Holocene. High resolution modeling of the glacial isostatic rebound reveals that the largest glaciers in Nordaustlandet and eastern Spitsbergen survived the Early Holocene warming, while the smaller, more peripheral glaciers, especially in the northwest, started to form about 5,500 years ago, and reached 3/4 of their current size about 600 years ago. Relative sea level has been rising during the last few millennia in the north and western parts of Spitsbergen, while land still emerges in the remaining part of Svalbard. Here we show that this sea level rise in the northwest is caused by the regrowth of glaciers in the Mid- to Late Holocene that slowed down, and even reversed, the post-glacial isostatic uplift and caused the crust to subside over large areas of Spitsbergen.”
“In the Korovinskoe record (Fig. 10A) the first increase in temperate deciduous tree/shrub percentages is dated to ca. 10,400 cal BP followed by a second, more pronounced increase (up to 21%) between ca. 10,100 and 9800 cal BP. The latter rise corresponds to maximum summer SSTs (i.e. 6-7°C above the mean modern SST value) reconstructed in the NE North Atlantic (Fig. 10E) and the NW Barents Sea (Fig. 10F).”
“A pollen-based reconstruction of the summer temperature anomaly at Lake Kurjanovas (Fig. 1) in Latvia suggests that the warmest interval in the area located ca. 270 km west of Korovinskoe occurred ca. 8100-5600 cal BP (Fig. 10C; Heikkila and Seppa, 2010).”
“Mangerud and Svendsen (2018) reported appearance of the most warmth-demanding mollusk species ca. 1000 km farther north of its current distribution indicating that August temperatures on Svalbard were 6°C warmer at around 10,200-9200 cal BP and that the regional climate was as warm as present by ca. 11,000 cal BP.”
“The core 70 site is characterised by extensive modern sea ice conditions (≈80% SpSIC [Spring Sea Ice Concentration]) and the downcore record represents a gradual evolution of sea ice cover in the northern Barents Sea from ice-free conditions during the early Holocene to prolonged seasonal sea ice presence prevalent in the region today. The primarily insolation-controlled southward expansion of sea ice cover previously inferred for the core site throughout the Holocene (Belt et al., 2015; Berben et al., 2017) is reflected in the CT model assessment. Consistent with the onset of the Holocene Thermal Maximum and the resulting proximity of the annual maximum sea ice edge to the core site between ca. 9.5–8.5 cal kyr BP evident from low PIIIIP25-derived SpSIC (ca. 5–15%), the CT model predicts mostly marginal sea ice conditions during this interval.”
“From ca. 10.0–1.5 cal kyr BP, ice-free conditions characterised the core 11 site, as evidenced by consistently low SpSIC (ca. <10%) and marginal sea ice conditions predicted by the CT model, and further supported by an enhancement of AW [Arctic Water] inflow to the core site from ca. 9.8 cal kyr BP (Groot et al., 2014)”
This article appeared on the NoTricksZone website at http://notrickszone.com/2018/12/20/arctic-glaciers-advanced-16-km-during-2008-2016-in-a-region-that-was-6c-warmer-9000-years-ago/