Project

Radiocarbon; Stable Isotopes; Palaeoclimatology; Dendrochronology; Greenland Stadial 1; Late Glacial; Early Holocene; AMS; Younger Dryas; Environmental Archive

Lead
Jährlich aufgelöste Jahrringchronologien sind wichtige Umweltarchive. Sie decken die meisten extratropischen Regionen unserer Erde ab und können tausende von Jahre in die Vergangenheit zurückreichen. Da die Archive jahrgenau datiert werden können, sind sie für Paläoklimatologie und Paläoökologie, aber auch für Archäologie und Radiokarbon Datierung von unschätzbarem Wert.
Lay summary
Ziel dieses Projektes ist es, die weltweit längste Jahrringchronologie welche momentan bis 12’594 Jahre vor Heute (BP) zurückreicht, lückenlos und absolut datiert um weitere rund 2'000 Jahre in den Übergang zwischen der letzten Eiszeit und dem Holozän zu verlängern. Ein neuer, bezüglich Umfang und Alter weltweit einzigartiger Fund von 257 Kiefern innerhalb der Stadt Zürich soll dieses Ziel nun ermöglichen.   Mit vereinten Kräften einer Deutsch-Schweizer Kollaboration unter Zuhilfenahme von dendrochronologischen Jahrringbreite- und Dichtemessungen soll nicht nur die Jahrringchronologie verlängert und verbessert werden, sondern gleichzeitig auch ein  Datensatz  zeitlich hochaufgelöster Radiokarbon (¹4C) und Stabiler (δ¹³C und δ¹8O ) Isotopen generiert werden. Der Ansatz mehrere Dendro- und Isotopen Parameter gleichzeitig zu messen, soll nicht nur die Erarbeitung einer erweiterten Chronologie  unterstützen und absichern, sondern vor allem auch unser paläoklimatologisches Verständnis des Spätglazial vor und nach der Jüngeren Dryas - einer Zeit starker klimatischer Veränderungen - erweitern.

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Last update: 09.02.2015

Active participation

Communication	Title	Media	Place	Year

Title	Year

Annually resolved and absolutely dated tree-ring chronologies are important paleo-environmental proxy archives, because they can cover several thousands of years and robust master chronologies are available for many different regions around the globe. Moreover, the unique dating accuracy has a strong impact on many fields of application, including paleoclimatology and paleoecology, but also archaeology and radiocarbon dating. Here, we strive to a) consolidate and b) extend the worldwide longest continuous tree-ring width chronology from Hohenheim/Zurich, which currently reaches back to 12 594 before present (BP). An exceptional discovery of 257 individual pine trees within the town of Zurich in 2013 (herein referred to as the Binz material), for which first radiocarbon dates now suggest a time window roughly between 14 000 and 12 1000 BP, implies strong evidence to fill the existing gaps in the Late Glacial tree-ring chronology around 12 600 BP. If indeed successful, the worldwide longest, absolutely dated and continuous tree-ring record would be extended by almost two millennia until around 14 300 BP, thus covering a particularly interesting climatological transition from the Last Ice Age into the Early Holocene - a period for which proxy evidence is generally scarce. Achieving this remarkable task, however, requires joint forces across an international Swiss-German collaboration, which will in addition to ample new dendrochronological ring width and density measurements also generate a unique record of corresponding high-resolution radiocarbon (¹4C) dates as well as stable isotope ratios (d¹³C and d¹8O). The herein proposed multi-parameter approach will not only support and strengthen the chronology development process typically based on ring width measurements alone, but particularly also our palaeoenvironmental understanding of the Late Glacial period surrounding the Younger Dryas, a period during which rapid climatic shifts likely provide a natural analogue to the most recent anthropogenic change.The new multi-parameter tree-ring archive will further allow extending the highly rewarded (tree-ring-based) terrestrial radiocarbon calibration curve for more than 2 000 years into late glacial times improving considerably radiocarbon dating accuracy for archaeologists and geological sciences. In combination with several available marine radiocarbon records and complementary radioisotopic records from polar ice cores (¹°Be, ³6Cl), an exceptionally precise and highly resolved calibration curve will also reveal historical information about changes in and levels of solar activity, as well as mounting evidence for trends and extremes at the putative transition of generally colder to warmer climatic conditions, associated with rapid changes in the Earth’s hydrological cycle. In addition, decadal to centennial ¹4C variations in tree-rings will be compared to the mirror image of ¹°Be in polar ice cores, therefore anchoring the ice core time scale to the tree-ring scale. Employment of the proposed high-resolution stable isotopes (d¹³C and d¹8O) from the same trees will further help us to more accurately capture the full range of synaptic-scale late glacial temperature and likely even also precipitation variability.