A5010273563- Geology and Paleoclimatology Research
- Species Distribution and Climate Change
- Ecology and Vegetation Dynamics Studies
- Geological formations and processes
- Tree-ring climate responses
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Archaeology and ancient environmental studies
- Plant and animal studies
- Pleistocene-Era Hominins and Archaeology
- Marine and environmental studies
- Geochemistry and Geologic Mapping
- Aquatic Ecosystems and Phytoplankton Dynamics
- Climate change and permafrost
- Aquatic Ecosystems and Biodiversity
- Geological Studies and Exploration
- Marine Biology and Ecology Research
- Paleontology and Stratigraphy of Fossils
- Peatlands and Wetlands Ecology
- Soil Geostatistics and Mapping
- Cryospheric studies and observations
- Groundwater and Isotope Geochemistry
- Zoonotic diseases and public health
- Data Analysis with R
- Geological and Geophysical Studies
Bjerknes Centre for Climate Research
2016-2025
University of Bergen
2016-2025
Norwegian Institute for Nature Research
2024
Faculty of 1000 (United States)
2021
National University of Tierra del Fuego
2021
Ecological Society of America
2016
John Wiley & Sons (United States)
2016
Stockholm University
2016
University College London
2006-2007
IBM (United States)
2004
Abstract The lack of a precisely-dated, unequivocal climate proxy from northern China, where precipitation variability is traditionally considered as an East Asian summer monsoon (EASM) indicator, impedes our understanding the behaviour and dynamics EASM. Here we present well-dated, pollen-based, ~20-yr-resolution quantitative reconstruction (derived using transfer function) alpine lake in North which provides for first time direct record EASM evolution since 14.7 ka (ka = thousands years...
Intercept-based methods of generating a point estimate calibrated radiocarbon date are very popular, but exhibit undesirable behaviour. They highly sensitive to the mean and adjustments calibration curve. Other give more stable results. The weighted average probability distribution function is recommended as best central-point estimate, consideration should be given using full rather than in developing age-depth models.
Abstract. The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy arguments about only possible if they based reproducible features several reliably dated datasets. Here we focus the last 9000 years, explore results 36 Holocene pollen-based July mean annual temperature reconstructions from Northern Europe by stacking them to create summary curves,...
Fossil pollen records are well-established indicators of past vegetation changes. The prevalence across environmental settings including lakes, wetlands, and marine sediments, has made palynology one the most ubiquitous valuable tools for studying climatic change globally decades. A complementary research focus been development statistical techniques to derive quantitative estimates conditions from assemblages. This paper reviews commonly used their rationale seeks provide a resource...
In a rapidly changing climate, alpine plants may persist by adapting to new conditions. However, the rate at which climate is might exceed of adaptation through evolutionary processes in long-lived plants. Persistence depend on phenotypic plasticity morphology and physiology. Here we investigated patterns leaf trait variation including area, thickness, specific dry matter content, nutrients (C, N, P) isotopes (δ13C δ15N) across an elevation gradient Gongga Mountain, Sichuan Province, China....
Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind East Asian Summer Monsoon its interaction with westerly jet stream remain poorly understood. We present quantitative derived from 101 fossil pollen records analyse them help a minimal empirical model. show jet-stream axis shifted gradually southward became less tilted since middle Holocene. This...
We present a procedure for estimating age-depth relationships in stratigraphical sequences by means of generalized mixed-effect regression using an ancillary function the partitioning fixed effect and random corresponding to degree representativity individual calibrated dates particular section sedimentary sequence. The uses mid-point estimates ages combination with central distributional range as basis relationship between age depth. Further, it combines variability at layers (within-object...
Oxygen isotopes are sensitive tracers of climate change in tropical regions. Abrupt shifts up to 18 per mil the oxygen isotope ratio diatom silica have been found a 14,000-year record from two alpine lakes on Mt. Kenya. Interpretation tropical-montane records is controversial, especially concerning relative roles precipitation and temperature. Here, we argue that Holocene variations δ O better explained by lake moisture balance than temperature-induced fractionation. Episodes heavy...
In contrast with macroorganisms, whose geographical ranges are typically restricted, many microbial species appear to have cosmopolitan distributions. This observation has been explained as a consequence of ubiquitous dispersal caused by the enormous population sizes species. Recently, this "everything is everywhere, but, environment selects" theory challenged detection considerable regional genetic variability within morphospecies. We demonstrate that, contrary what expected under...
The construction of accurate age–depth relationships and a realistic assessment their uncertainties is one the fundamental prerequisites for comparing correlating late Quaternary stratigraphical proxy records. Four widely used modelling routines – CLAM, OxCal, Bacon Bchron were tested using radiocarbon dates simulated from varved sediment stratigraphies. All methods produce mean models that are close to true varve age, but uncertainty estimation differs considerably among models. Age usually...
Background Although arctic lakes have responded sensitively to 20th-century climate change, it remains uncertain how these ecological transformations compare with alpine and montane-boreal counterparts over the same interval. Furthermore, is unclear what degree other forcings, including atmospheric deposition of anthropogenic reactive nitrogen (Nr), participated in recent regime shifts. Diatom-based paleolimnological syntheses offer an effective tool for retrospective assessments past...
Plant functional traits vary consistently along climate gradients and are therefore potential predictors of plant community response to change. We test this space-for-time assumption by combining a spatial gradient study with whole-community turf transplantation temperature precipitation in network 12 grassland sites Southern Norway. Using data on eight for 169 species annual vegetation censuses 235 turfs over 5 yr, we quantify trait-based responses change comparing observed dynamics...
Abstract The Arctic is warming twice as fast the rest of planet, leading to rapid changes in species composition and plant functional trait variation. Landscape-level maps vegetation distributions are required expand spatially-limited plot studies, overcome sampling biases associated with most accessible research areas, create baselines from which monitor environmental change. Unmanned aerial vehicles (UAVs) have emerged a low-cost method generate high-resolution imagery bridge gap between...
High resolution flow speed reconstructions of two core sites located on Gardar Drift in the northeast Atlantic Basin and Orphan Knoll northwest reveal a long‐term decrease Northeast Deep Water (NEADW) after 6,500 years. Benthic foraminiferal oxygen isotopes currently bathed NEADW show 0.2‰ depletion years, shortly start development carbon isotope gradient between Norwegian Sea Water. We consider these changes near‐bottom vigor benthic records to mark significant reorganization Holocene deep...
Abstract. A synthesis of well-dated high-resolution pollen records suggests a spatial structure in the 8200 cal yr BP event northern Europe. The temperate, thermophilous tree taxa, especially Corylus, Ulmus, and Alnus, decline abruptly between 8300 8000 at most sites located south 61° N, whereas there is no clear change values North-European tree-line region. Pollen-based quantitative temperature reconstructions several other, independent palaeoclimate proxies, such as lacustrine...
Research Article| September 01, 2011 A 100 yr record of ocean temperature control on the stability Jakobshavn Isbrae, West Greenland Jeremy Lloyd; Lloyd 1Department Geography, Durham University, South Road, DH1 3LE, UK Search for other works by this author on: GSW Google Scholar Matthias Moros; Moros 2Baltic Sea Institute, Seestrasse 15, 18119 Rostock, Germany3Uni Bjerknes Centre Climate Research, Allégaten 55, 5007 Bergen, Norway Kerstin Perner; Perner Germany Richard J. Telford; Telford...
We investigate the effect that uneven sampling of environmental gradient has on transfer-function performance using simulated community data. find cross-validated estimates root mean squared error prediction can be strongly biased if observations are very unevenly distributed along gradient. This occurs because species optima more precisely known (and analogues available) in part with most observations, hence precise here, and compensate for less well sampled parts weighted averaging modern...