A5010999854- Geology and Paleoclimatology Research
- Archaeology and ancient environmental studies
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Geomagnetism and Paleomagnetism Studies
- Isotope Analysis in Ecology
- Pleistocene-Era Hominins and Archaeology
- Tree-ring climate responses
- Radioactivity and Radon Measurements
- Astro and Planetary Science
- Geological and Geochemical Analysis
- Marine and environmental studies
- Atmospheric and Environmental Gas Dynamics
- Solar and Space Plasma Dynamics
- Climate variability and models
- Planetary Science and Exploration
- Hydrocarbon exploration and reservoir analysis
- Geological Studies and Exploration
- Geological formations and processes
- Arctic and Antarctic ice dynamics
- Radioactive contamination and transfer
- earthquake and tectonic studies
- Geochemistry and Geologic Mapping
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
University of Bremen
2020-2025
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
2020-2025
Oeschger Centre for Climate Change Research
2018-2023
University of Bern
2017-2023
Lund University
2013-2021
University of Arizona
2020
Institut de l'Information Scientifique et Technique
2020
Quaternary Research Association
2013-2014
Leibniz Institute for Baltic Sea Research
2012
ABSTRACT Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating fluctuations in atmospheric C concentration. Although curves are constructed from independently archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume international both Northern...
Abstract The origin of two large peaks in the atmospheric radiocarbon ( 14 C) concentration at AD 774/5 and 993/4 is still debated. There consensus, however, that these features can only be explained by an increase C production rate due to extraterrestrial event. Here we provide evidence were most likely produced extreme solar events, based on several new annually resolved 10 Be measurements from both Arctic Antarctic ice cores. Using core 36 Cl data pair with Be, further show events...
Abstract. We present the WD2014 chronology for upper part (0–2850 m; 31.2 ka BP) of West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The is based on counting annual layers observed in chemical, dust and electrical conductivity records. These are caused by seasonal changes source, transport, deposition aerosols. measurements were interpreted manually with aid two automated methods. validated comparing to high-accuracy, absolutely dated chronologies. For Holocene, cosmogenic isotope...
The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from Greenland NEEM core to reconstruct environmental alterations in source regions accompanying these changes. Separating transport effects, find strongly reduced terrestrial biogenic emissions glacial times reflecting net loss of vegetated...
Abstract. Investigations of past climate dynamics rely on accurate and precise chronologies the employed reconstructions. The radiocarbon dating calibration curve (IntCal13) Greenland ice core chronology (GICC05) represent two most widely used chronological frameworks in paleoclimatology ∼ 50 000 years. However, comparisons records anchored these are hampered by precision accuracy both timescales. Here we use common variations production rates 14C 10Be recorded tree-rings cores,...
Abstract. During the last glacial period Northern Hemisphere climate was characterized by extreme and abrupt changes, so-called Dansgaard–Oeschger (DO) events. Most clearly observed as temperature changes in Greenland ice-core records, their climatic imprint geographically widespread. However, temporal relation between DO events other regions is uncertain due to chronological uncertainties of each archive, limiting our ability test hypotheses synchronous change. In contrast, assumption...
Abstract. The last glacial period is characterized by a number of millennial climate events that have been identified in both Greenland and Antarctic ice cores are abrupt records. mechanisms governing this variability remain puzzle requires precise synchronization from the two hemispheres to be resolved. Previously, synchronized primarily via their common records gas concentrations or isotopes trapped air cosmogenic measured on ice. In work, we apply core volcanic proxies annual layer...
Significance This study provides evidence of an enormous solar storm around 2,610 B.P. It is only the third such event reliably documented and comparable with strongest detected at AD 774/775. The years stands out because its particular signature in radionuclide data [i.e., carbon-14 ( 14 C) alone does not allow for unequivocal detection event]. illustrates that present efforts to find events based solely on C likely lead underestimated number potentially devastating our society. In addition...
Reversing the field Do terrestrial geomagnetic reversals have an effect on Earth's climate? Cooper et al. created a precisely dated radiocarbon record around time of Laschamps reversal about 41,000 years ago from rings New Zealand swamp kauri trees. This reveals substantial increase in carbon-14 content atmosphere culminating during period weakening magnetic strength preceding polarity switch. The authors modeled consequences this event and concluded that minimum caused changes atmospheric...
Recent revisions in the sunspot records illustrate challenges related to obtaining a 400-year-long observational record of past solar-activity changes. Cosmogenic radionuclides offer possibility an alternative and completely independent solar variability. Here, we that these great potential for quantitative reconstructions far back into past, provide updated radionuclide-based 2000 years. However, cosmogenic-radionuclide are also influenced by processes activity, leading need critical...
Abstract During solar storms, the Sun expels large amounts of energetic particles (SEP) that can react with Earth’s atmospheric constituents and produce cosmogenic radionuclides such as 14 C, 10 Be 36 Cl. Here we present Cl data measured in ice cores from Greenland Antarctica. The consistently show one largest production peaks detected so far, most likely produced by an extreme SEP event hit Earth 9125 years BP (before present, i.e., before 1950 CE), 7176 BCE. Using Cl/ ratio, demonstrate...
Abstract The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic particles (SEPs) that dramatically disrupt the near-Earth radiation environment. Such have been directly studied for last decades but little is known about occurrence and magnitude rare, extreme SEP events. Presently, a few produced measurable signals in cosmogenic radionuclides such as 14 C, 10 Be 36 Cl found. Analyzing annual C concentrations tree-rings from Switzerland, Germany, Ireland,...
Abstract. During the last glacial period, proxy records throughout Northern Hemisphere document a succession of rapid millennial-scale warming events, called Dansgaard–Oeschger (DO) events. A range different mechanisms has been proposed that can produce similar in model experiments; however, progression and ultimate trigger events are still unknown. Because their fast nature, is challenging to reconstruct from paleoclimate data due limited temporal resolution achievable many archives...
Abstract. The effect of external forcings on atmospheric circulation is debated. Due to the short observational period, analysis role hampered, making it difficult assess sensitivity forcings, as well persistence effects. In observations, average response tropical volcanic eruptions a positive North Atlantic Oscillation (NAO) during following winter. However, past major exceeding magnitude instrumental era could have had more lasting Decadal NAO variability has been suggested follow 11-year...
Abstract Cosmogenic radionuclide records from polar ice cores provide unique insights into past cosmic ray flux variations. They allow reconstructions of solar activity, space weather, and geomagnetic field changes, carbon cycle changes. However, all these applications rely on the proportionality core to global mean production rate This premise has been long debated a model data‐perspective. Here, we address this issue through atmospheric mixing experiments comparison independent data. We...
Variations in the atmospheric production rate of cosmogenic 10Be lead to global changes depositional fluxes. This may serve as a powerful tool for synchronizing various paleoclimate archives. For robust synchronization, however, it is essential understand pathways from its upper atmosphere deposition sediments and ice. While deposited ice within one two years after production, marine less direct, complicating use synchronization. To address this issue, we investigate response authigenic...
The annual
Abstract Since it is currently not understood how changes in 14 C production rate ( Q ), and the carbon cycle, can be combined to explain reconstructed atmospheric Δ record, we discuss possible reasons for this knowledge gap. Reviewing literature, exclude that content of atoms atmosphere, which produce cosmogenic after being hit by galactic cosmic rays, might responsible parts observed differences. When combining with cycle changes, one needs understand inventory, are partially...