A 5500-year oxygen isotope record of high arctic environmental change from southern Spitsbergen

Abstract

The oxygen isotope composition of chironomid head capsules in a sediment core spanning the past 5500 years from lake Svartvatnet in southern Spitsbergen was used to reconstruct the oxygen isotope composition of lake water (δ 18 Olw) and local precipitation. The δ 18 Olw values display shifts from the baseline variability consistent with the timing of recognized historical climatic episodes, such as the Roman Warm Period, the Dark Ages Cold Period and the Little Ice Age. The highest values of the record, ca. 3‰ above modern δ 18 Olw values, occur at ca. 1900-1800 cal. yr BP. Three negative excursions increasing in intensity toward the present, at 3400-3200, 1250-1100 and 350-50 cal. yr BP, are tentatively linked to roughly synchronous episodes of increased glacier activity and general cold spells around the northern North Atlantic. Their manifestation in the Svartvatnet δ 18 Olw record testify to the sensitivity and potential of high Arctic lacustrine δ 18 Ochir records in tracking terrestrial climate evolution, but also highlight nonlinear dynamics within the northern North Atlantic hydroclimatic system. The Little Ice Age period at 350-50 cal. yr BP displays a remarkable 8-9‰ drop in δ 18 Olw values, construed to predominantly represent significantly decreased winter temperatures during a period of increased seasonal differences and extended sea ice cover inducing changes in moisture source regions.

Synchronized proxy‐based temperature reconstructions reveal mid‐ to late Holocene climate oscillations in High Arctic Svalbard

“…A more detailed description of the analytical and data processing methods was given by Arppe et al . (). Note that the δ 18 O chir reconstruction of MAT should be considered tentative owing to the reasons discussed below.…”

“…() without acid treatment, and was described further by Arppe et al . () and Kurki (). Approximately 80 μg of cleaned chironomid head capsules was weighed in silver capsules, and measurements of δ 18 O values were made with a Finnigan ThermoQuest TC/EA coupled to a Delta Plus Advantage isotope ratio mass spectrometer at the Laboratory of Chronology, Finnish Museum of Natural History.…”

“…They range from 1.4 to 3.6‰ (mean 1.6‰) and 1.9 to 4.5˚C (mean 2.1˚C) for the d 18 O lake water and MAT reconstructions, respectively. A more detailed description of the analytical and data processing methods was given by Arppe et al (2017). Note that the d 18 O chir reconstruction of MAT should be considered tentative owing to the reasons discussed below.…”

“…Indeed, the record of d 18 O values, while carrying a strong temperature-dependent signal, is very probably also influenced by other environmental factors such as variations in sea ice extent around Spitsbergen, and should not be considered solely to reflect MAT. A detailed discussion of the d 18 O record was previously presented by Arppe et al (2017).…”

Effects of chemical pretreatment and intra- and inter-specimen variability on δ18O of aquatic insect remains

“…It would be expected that analysing material sampled at higher temporal resolution would reduce the number of sclerites in a sample, and thus the inter-sclerite variability. For example, high-resolution aquatic insect d 18 O records have been produced using chironomid head capsules, which are generally more abundant in lake sediments than remains of water beetles (Verbruggen et al 2010b;Arppe et al 2017;Lombino 2014;Lasher et al 2017).…”