A5041073796- Geology and Paleoclimatology Research
- Pleistocene-Era Hominins and Archaeology
- Geological formations and processes
- Archaeology and ancient environmental studies
- Isotope Analysis in Ecology
- Marine and environmental studies
- Tree-ring climate responses
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Pacific and Southeast Asian Studies
- Climate change and permafrost
- Geological Studies and Exploration
- Aquatic Ecosystems and Phytoplankton Dynamics
- Paleontology and Stratigraphy of Fossils
- Climate variability and models
- Hydrocarbon exploration and reservoir analysis
- Coastal wetland ecosystem dynamics
- Transboundary Water Resource Management
- Geological and Geophysical Studies
- Scientific Research and Discoveries
- Geomagnetism and Paleomagnetism Studies
- Polar Research and Ecology
- Peatlands and Wetlands Ecology
- Geochemistry and Geologic Mapping
- Ancient and Medieval Archaeology Studies
Bolin Centre for Climate Research
2014-2022
Stockholm University
2013-2022
Collège Boréal
2020
Biologie des Organismes et Écosystèmes Aquatiques
2020
Stockholm Resilience Centre
2020
Lund University
1995-2005
Quaternary Research Association
1996-2003
Geological Survey of Denmark and Greenland
1999
The Melting Is in the Details Global sea level rises and falls as ice sheets glaciers melt grow, providing an integrated picture of changes volume but little information about how much individual fields are contributing to those variations. Knowing regional structure variability during glaciations deglaciations will clarify mechanisms glacial cycle. Clark et al. (p. 710 ) compiled analyzed more than 5000 radiocarbon cosmogenic surface exposure ages order develop a record maximum extent...
It is suggested that the GRIP Greenland ice-core should constitute stratotype for Last Termination. Based on oxygen isotope signal in core, a new event stratigraphy spanning time interval from ca. 22.0 to 11.5 k yr BP (ca. 19.0–10.0 14C BP) proposed North Atlantic region. This covers period Glacial Maximum, through Termination 1 of deep-ocean record, Pleistocene–Holocene boundary, and encompasses Late-glacial traditional northwest European stratigraphy. The isotopic record this divided into...
On the basis of synchronization three carbon-14 (14C)-dated lacustrine sequences from Sweden with tree ring and ice core records, absolute age Younger Dryas-Preboreal climatic shift was determined to be 11,450 11,390 +/- 80 years before present. A 150-year-long cooling in early Preboreal, associated rising Delta14C values, is evident all records indicates an ocean ventilation change. This similar earlier deglacial coolings, box-model calculations suggest that they may have been result...
Abstract The Les Echets sediment sequence has recently been the subject of a high‐resolution, multi‐proxy study which revealed shifts in lake productivity linked to Greenland stadials and interstadials over last 40 ka (Wohlfarth et al. , 2008 . Rapid ecosystem response abrupt climate changes during glacial period western Europe, 40–16 ka. Geology 36 : 407–410). Here we present new elemental data for this as acquired using an X‐ray fluorescence core scanning system provides situ continuous,...
Abstract The Younger Dryas (YD) cold reversal interrupts the warming climate of deglaciation with global climatic impacts. sudden cooling is typically linked to an abrupt slowdown Atlantic Meridional Overturning Circulation (AMOC) in response meltwater discharges from ice sheets. However, inconsistencies regarding YD-response European summer temperatures have cast doubt whether concept provides a sufficient explanation. Here we present results high-resolution simulation together new July...
Significance We present a high-resolution, replicated speleothem δ 18 O record from Klang Cave in southern Thailand that characterizes rainfall variation NCIP over the past 2,700 y. This reveals notable dry climate conditions during current and warm periods, similar to observations SCIP, which resemble enhanced El Niño-like conditions. Using newly developed ITCZ shift index, we find southward shifted early MWP CWP. Our results suggest detecting changes due anthropogenic forcing still remains...
The lake sediments of Hässeldala Port in south-east Sweden provide an archive local and regional environmental conditions ~14.5-9.5 ka BP (thousand years before present) allow testing DNA sequencing techniques to reconstruct past vegetation changes. We combined shotgun with plant micro- macrofossil analyses investigate dating the Allerød (14.1-12.7 BP), Younger Dryas (12.7-11.7 BP) Preboreal (<11.7 BP). Number reads taxa were not associated sample age or organic content. This suggests that,...
The AMS 14C technique has the advantage that small samples of Late Quaternary age can be dated with high accuracy, and errors due to reservoir effects avoided if specifically determined terrestrial micro- macrofossils are measured. However, obtain such high-accuracy measurements, it is important how handled prior treatment in radiocarbon laboratories. Here we present a set 51 which 31 dates gave expected ages 20 resulted anomalously young ages, despite fact all consisted clearly identified...
Research Article| May 01, 2008 Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40–16 ka Barbara Wohlfarth; Wohlfarth 1Department of Geology and Geochemistry, Stockholm University, 10691 Stockholm, Sweden Search for other works by this author on: GSW Google Scholar Daniel Veres; Veres 2Emil Racovita Speleological Institute, 400006 Cluj, Romania Linda Ampel; Ampel 3Department Physical Geography Quaternary Geology, Terri Lacourse; Lacourse...
X‐ray fluorescence ( XRF ) core scanning has become widely available for geological studies during the last decade. The data obtained from scanning, however, may be strongly influenced by amount of organic matter, water content, density and porosity sediment matrix. In this study we discuss usefulness to distinguish different kinds organic‐rich sediments peat based on examples tropical Lakes Kumphawapi Nong Leng Sai in Thailand. We examined how sedimentary factors influence analyses...
Abstract Sources and timing of freshwater forcing relative to hydroclimate shifts recorded in Greenland ice cores at the onset Younger Dryas, ∼12,800 years ago, remain speculative. Here we show that progressive Fennoscandian Ice Sheet (FIS) melting 13,100–12,880 ago generates a dipole with drier–colder conditions Northern Europe wetter–warmer Greenland. FIS culminates 12,880 synchronously start Stadial 1 large-scale transition lasting ∼180 years. Transient climate model simulations forced...
The increasing focus on the chronology of environmental and climatic changes last glacial‐interglacial transition has led to several independent attempts try calibrate 14 C time‐scale beyond Holocene. Late Weichselian Gotiglacial varved clays Swedish Time Scale could potentially be used for this purpose. reliability is discussed as well different ways using calibrating chronology. strategy initial results from an ongoing calibration project are presented. They show clearly that, if right...
A tephra layer of rhyolitic composition has been recorded in sediments from Lake Madtjärn, southwestern Sweden. Geochemical analyses have shown that the is identical to component middle Younger Dryas Vedde Ash. series AMS radiocarbon measurements places age within a 14C plateau at 10 400–10 300 y BP. Based on linear sedimentation rate and assumptions about apparent synchroneity changes lake sediments, tree rings ice-core records, calendar year concentrations estimated 12 045–11 975 yr BP,...
Abstract The sediment sequence from Hässeldala port in southeastern Sweden provides a unique Lateglacial/early Holocene record that contains five different tephra layers. Three of these have been geochemically identified as the Borrobol Tephra, Hässeldalen Tephra and 10‐ka Askja Tephra. Twenty‐eight high‐resolution 14 C measurements obtained three age models based on Bayesian statistics are employed to provide estimates for chrono‐ pollen stratigraphic framework supports position found at...
Distal tephra horizons, particularly within lacustrine sequences, are increasingly being used as time-synchronous marker horizons palaeoclimatic and palaeoenvironmental investigations. As sedimentary features marking the presence of these so-called cryptotephras absent to naked eye, it is some importance that stratigraphic position representing primary airfall, likewise timing volcanic event, accurately consistently recorded amongst deposits. Often shards from a cryptotephra deposit can be...
Research Article| November 01, 2007 Present-day temperatures in northern Scandinavia during the last glaciation K.F. Helmens; Helmens 1Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden Search for other works by this author on: GSW Google Scholar J.A.A. Bos; Bos 2Department Paleoclimatology Geomorphology, Faculty Earth Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Netherlands S. Engels; Engels C.J. Van...