Holocene changes in atmospheric circulation recorded in the oxygen-isotope stratigraphy of lacustrine carbonates from northern Sweden

Abstract

Abstract:The oxygen-isotope composition of local precipitation (d 18 OP) is reconstructed from carbonate lakesediment components in a sediment core covering the last 10000 calendar years from Lake Tibetanus, a small, hydrologically open, groundwater-fed lake in the Abisko area, northern Sweden. Comparison of the d 18O P history with a pollen-based palaeotemperature record from the same core clearly reveals pronounced deviations from the normally expected temporal d 18 O P -temperature relation (so-called 'Dansgaard relation') that may be a function of changing oceanicity. The transition from relatively moist, maritime conditions in the early Holocene to a much drier climate after 6500 cal. BP is re ected by major changes in forest extent and composition as recorded by pollen and plant macrofossil data. At the time of maximum in uence of westerly air-mass circulation (high zonal index) c. 9500 cal. BP, brought about by high summer insolation and enhanced meridional pressure gradients, d 18 OP at Lake Tibetanus was about 2‰ higher than would be predicted by the modern isotope-temperature relation. The occurrence of long-term changes in d 18O P -temperature relations, which are more sensitive measures of palaeoclimate than either d 18O P or temperature alone, needs to be taken into account when extracting palaeoclimatic information from continental oxygen-isotope records.

Multi-proxy studies in palaeolimnology

“…In the Egyptian Nile delta lakes, hydrological and salinity modifications resulted from the year-round inflow of fresh irrigation water controlled by the Nile dams and the rise in the freshwater table due to inadequate drainage in the flat delta. Azolla nilotica recently became extinct in these lakes (Birks 2002), probably as a result of eutrophication and salinity changes. Without the evidence provided by the analysis of plant macrofossils, pollen, diatoms, mollusca, foraminifera, ostracods, and other animal remains from the same cores, the extinction of A. nilotica would not have been recorded and the likely causes would have remained obscure.…”

“…Meriläinen et al 2001;Fisher et al 2003;Hynynen et al 2004;Das et al 2005;Sayer et al 2006) and stable isotopes (e.g. Finney et al 2000Finney et al , 2002Hammarlund et al 2002;Veski et al 2004;Wooller et al 2004;Seppä et al 2005). As well as the development of under-utilised fossil proxies (e.g.…”

Climate Change During the Holocene (Past 12,000 Years)

“…The oxygen-isotopic palaeothermometry method is being widely applied not only to organic carbonates of marine origin but also to freshwater lake sediments (algae, lake marl), inorganic carbonate in caves (stalactites and stalagmites), and continental glaciers (mountain glaciers, polar ice sheets) (Mörner 1980;Seppä and Hammarlund 2000;Baldini et al 2002;Hammarlund et al 2002Hammarlund et al , 2003Hammarlund et al , 2005Rasmussen et al 2006;Kobashi et al 2007Kobashi et al , 2008.…”

Late Holocene lake level dynamics inferred from magnetic susceptibility and stable oxygen isotope data: Lake Elsinore, southern California (USA)

“…18 O values of inorganic lacustrine calcite are a well-documented climate proxy for lake studies (Stuiver 1970;McKenzie and Hollander 1993;Drummond et al 1995;Anderson et al 1997;Yu et al 1997;Teranes and McKenzie 2001;Hammarlund et al 2002;Kirby et al 2002c, d). In arid lake environments, such as Lake Elsinore, there are multiple studies purporting traditional interpretations of 18 O (calcite) values in terms of climate-forced relative lake level change (Benson et al 1991(Benson et al , 1996(Benson et al , 1998Li and Ku 1997;Li et al 2000;Seltzer et al 2000).…”