Mild Little Ice Age and unprecedented recent warmth in an 1800 year lake sediment record from Svalbard

Abstract

The Arctic region is subject to a great amplitude of climate variability and is currently undergoing large-scale changes due in part to anthropogenic global warming. Accurate projections of future change depend on anticipating the response of the Arctic climate system to forcing, and understanding how the response to human forcing will interact with natural climate variations. The Svalbard Archipelago occupies an important location for studying patterns and causes of Arctic climate variability; however, available paleoclimate records from Svalbard are of restricted use due to limitations of existing climate proxies. Here we present a sub-decadal-to multidecadal-scale record of summer temperature for the past 1800 yr from lake sediments of Kongressvatnet on West Spitsbergen, Svalbard, based on the fi rst instrumental calibration of the alkenone paleothermometer. The age model for the High Arctic lake sediments is based on 210 Pb, plutonium activity, and the fi rst application of tephrochronology to lake sediments in this region. We fi nd that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in West Spitsbergen in the course of the past 1800 yr, including during the Medieval Climate Anomaly, and that summers during the Little Ice Age (LIA) of the 18 th and 19 th centuries on Svalbard were not particularly cold, even though glaciers occupied their maximum Holocene extent. Our results suggest that increased wintertime precipitation, rather than cold temperatures, was responsible for LIA glaciations on Svalbard and that increased heat transport into the Arctic via the West Spitsbergen Current began ca. A.D. 1600.

Atlantic Water advection vs. glacier dynamics in northern Spitsbergen since early deglaciation

“…In contrast to conditions inferred above, some other studies state a general warming trend (Bonnet et al, 2010;D'Andrea et al, 2012;Jernas et al, 2013;Majewski et al, 2009;Spielhagen et al, 2011;Werner et al, 2011) as well as a strengthened influx of AW during the last 2 millennia in the Svalbard area (Groot et al, 2014;Rasmussen et al, 2012;Sarnthein et al, 2003;Ślubowska et al, 2005). However, as the midHolocene is missing in the present record (see Sect.…”

Northward advection of Atlantic water in the eastern Nordic Seas over the last 3000 yr

“…The specific location of core JM09-KA11-GC within the influence of both AW (WSC) and ArW (Sørkapp Current, Bear Island Current) suggests that although sea ice cover was probably enhanced over the western Barents Sea during this climate deterioration, this local area was affected by a highly fluctuating sea ice boundary with strong seasonal gradients characterized by an early spring break up of the winter sea ice, and a strong spring/early summer stratification and AW dominance during summer (favoring E. huxleyi). The specific surface expression at this site is further confirmed by the overall similarities between our E / C proxy (JM09-KA11-GC) and reconstructed atmospheric temperatures from a lake record in western Svalbard (D'Andrea et al, 2012), an area influenced by similar hydrological features (e.g., sea ice, the Sørkapp Current and the WSC). D'Andrea et al (2012) identified a temperature increase starting at ∼ 1600 AD over western Svalbard as well as mild LIA summer conditions, which they explained by a strengthened WSC (NAC), a strengthening only inferred in the present study from our JM09-KA11-GC coccolith record.…”

Assessment of heat sources on the control of fast flow of Vestfonna ice cap, Svalbard

“…Surface temperature variations also lead to temperature variations at depth but with different timescales than the penetration depth and temperatures certainly have not been constant in the past. It is known for example that there were periods warmer than the first decade of the 21st century (D'Andrea et al, 2012).…”