Stable isotope records for the last 10 000 years from Okshola cave (Fauske, northern Norway) and regional comparisons

Abstract

Abstract. The sensitivity of terrestrial environments to past changes in heat transport is expected to be manifested in Holocene climate proxy records on millennial to seasonal timescales. Stalagmite formation in the Okshola cave near Fauske (northern Norway) began at about 10.4 ka, soon after the valley was deglaciated. Past monitoring of the cave and surface has revealed stable modern conditions with uniform drip rates, relative humidity and temperature. Stable isotope records from two stalagmites provide time-series spanning from c. 10 380 yr to AD 1997; a banded, multi-coloured stalagmite (Oks82) was formed between 10 380 yr and 5050 yr, whereas a pristine, white stalagmite (FM3) covers the period from ∼7500 yr to the present. The stable oxygen isotope (δ 18 O c ), stable carbon isotope (δ 13 C c ), and growth rate records are interpreted as showing i) a negative correlation between cave/surface temperature and δ 18 O c , ii) a positive correlation between wetness and δ 13 C c , and iii) a positive correlation between temperature and growth rate. Following this, the data from Okshola show that the Holocene was characterised by high-variability climate in the early part, lowvariability climate in the middle part, and high-variability climate and shifts between two distinct modes in the late part.A total of nine Scandinavian stalagmite δ 18 O c records of comparable dating precision are now available for parts or most of the Holocene. None of them show a clear Holocene thermal optimum, suggesting that they are influenced by annual mean temperature (cave temperature) rather than seasonal temperature. For the last 1000 years, δ 18 O c values display a depletion-enrichment-depletion pattern commonly interpreted as reflecting the conventional view on climate Correspondence to: H. Linge (henriette.linge@geo.uib.no) development for the last millennium. Although the δ 18 O c records show similar patterns and amplitudes of change, the main challenges for utilising high-latitude stalagmites as palaeoclimate archives are i) the accuracy of the age models, ii) the ambiguity of the proxy signals, and iii) calibration with monitoring data.

Climate variability in the subarctic area for the last 2 millennia

“…The majority of the records highlight a transition between warmer and colder periods around the 14th century. Two records are characterized by an ending point after the 15th century (Arc_49, Linge et al, 2009;Arc_38, Berner et al, 2011). The time coverage of the MCA is about ∼ 200-250 years in most records (Fig.…”

“…ported to be as late as AD 1900 (e.g., Gunnarson et al, 2011;Isaksson et al, 2005;Linge et al, 2009;Massa et al, 2012) (Fig. 7a and b).…”

Late-Holocene temperature and precipitation changes in Vindelfjällen, mid-western Swedish Lapland, inferred from chironomid and geochemical data

“…yr BP, that are characterized by high Ti and low TOC values indicative of high (summer) precipitation and/or snow melt, correspond to periods with low δ 18 O in a speleothem (SG 93) from Soylegrotta (66°N13°E), Rana, Norway (Lauritzen and Lundberg, 1999). Low δ 18 O at this cave site is thought to represent warm and wet climate conditions (Linge et al, 2009;Sundqvist et al, 2010). The similarity between the Vuoksjávrátje Ti and SG 93 δ 18 O suggests a common response to changes in precipitation patterns, most likely due to shifts in the atmospheric circulation.…”

The Potential of Speleothems from Western Europe as Recorders of Regional Climate: A Critical Assessment of the SISAL Database

“…Presence/absence of growth and growth rate can thus both be powerful proxies for palaeoclimate conditions (e.g., [134,151,152]), with growth cessation and/or slow growth rates indicative of drier/colder stages, such as glacials and stadials ( Figure 3A). This is observed at the Scandinavian cave sites, where speleothem growth is limited to interglacial time periods [47,107]. Conversely, evidence from high Alpine caves has shown that "subglacial" speleothem growth is possible if carbonate dissolution is promoted by sulphide oxidation, for instance seen in stalagmites from Milchbach and Sieben Hengste Caves, Switzerland [104,114] and Spannagel Cave, Austria [119].…”