Inhaltsbereich
Highlights
A sharper look into the past for Archaeology and Climate Research
Annual strata in the Japanese Lake Suigetsu enable a more accurate calibration of radiocarbon datings
Christopher Bronk Ramsey et al. (2012): A Complete Terrestrial Radiocarbon Record for 11.2 – 52.8 kyr BP, Science, 338, (6105), 370-374, 10.1126/science.1226660
Science, October 2012: By using a new series of measurements of radiocarbon dates on seasonally laminated sediments from Lake Suigetsu in Japan, a more precise calibration of radiocarbon dating will be possible. In combination with an accurate count of the seasonal layered deposits in the lake, the study resulted in an unprecedented precision of the known 14C method with which it is now possible to date older objects of climate research and archeology more precisely than previously achievable. This is the result published by an international team of geoscientists led by Prof. Christopher Bronk Ramsey (University of Oxford) in the 19 October 2012 volume of the journal Science.
The Suigetsu Lake is ideal for using both dating methods, measurement of 14C and counting of annual layers, because deciduous trees grew on its shores during the last ice age, the leaves of which were preserved in large numbers in the sediments and are ideal for 14C dating. At the same time, this lake is one of the rare cases in which annual layers have been preserved in the sediment. Due to the long experience of Achim Brauer’s working group with creating precise calendar time scales from lake sediments, the scientists of Section 5.2 Climate Dynamics and Landscape Evolution at the GFZ were entrusted with this task.
More floods in the eastern Alps during cooling
A seasonally resolved flood reconstruction of the last 1600 years
Tina Swierczynski et al. (2012), A 1600 yr seasonally resolved record of decadal-scale flood variability from the Austrian Pre-Alps, Geology, November 2012, v. 40, p. 1047-1050, doi:10.1130/G33493.1
During periods of transition to cooler climatic conditions there was a distinct increase in the number of extreme floods. Such events were observed particularly during the Great Migration and the Early Middle Ages (AD 450-750) and the transition to the Little Ice Age (AD 1140-1520). In contrast, there was less flooding during the medieval warm phase (AD 1000-1140) and the coldest period of the Little Ice Age (AD 1600-1700).
An extremely brief reversal of the geomagnetic field, climate variability and a super volcano
Nowaczyk, N. R.; Arz, H. W.; Frank, U.; Kind, J.; Plessen, B. (2012): Dynamics of the Laschamp geomagnetic excursion from Black Sea sediments, Earth and Planetary Science Letters, 351-352, 54-69. doi:10.1016/j.epsl.2012.06.050.
EPSL, October 2012: 41,000 years ago, a complete and rapid reversal of the geomagnetic field occured. Magnetic studies at the Section 5.2 Climate Dynamics and Landscape Evolution at the GFZ on sediment cores from the Black Sea show that during this period, during the last ice age, a compass at the Black Sea would have pointed to the south instead of north. Moreover, data obtained by the research team formed around GFZ researchers Dr. Norbert Nowaczyk and Prof. Helge Arz, together with additional data from other studies in the North Atlantic, the South Pacific and Hawaii, prove that this polarity reversal was a global event. Their results are published in the latest issue of the scientific journal "Earth and Planetary Science Letters".
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The water flow of the Amazon River in a natural climate archive
Brienen, R.J.W., Helle, G., et al. (2012) : Oxygen isotopes in tree rings are a good proxy for Amazon precipitation and El Nino Southern Oscillation, Proceedings of the National Academy of Sciences of the United States of America; www.pnas.org/cgi/doi/10.1073/pnas.1205977109
PNAS, October 2012: Oxygen isotopes in tree rings are an excellent archive of precipitation dynamics in the tropical Amazon region. The precise determination of the ratios of stable oxygen isotopes (18O/16O) proves to be a new parameter for detecting the dynamics of the water cycle in tropical rain forest areas. It can therefore replace the classic climate observables such as tree ring width or wood density, which are unsuitable for high-quality reconstructions of climate conditions in tropical areas. These are the findings of a group of researchers from the Section 5.2 Climate Dynamics and Landscape Evolution at the GFZ, the Universities of Leeds (United Kingdom) and Utrecht (Netherlands), and the Institut de Recherche pour le Développement (IRD, Peru), published in online edition of the Proceedings of the National Academy of Sciences (PNAS).
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Climate drilling in the Arctic Circle
Martin Melles et al. (2012) 2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia, Science, DOI: 10.1126/science.1222135.
Science, July 2012: During the past 2.8 million years extreme warm periods occurred in the Arctic at irregular intervals. Analytical results from the longest sediment core that has ever been drilled in the terrestrial areas of the Arctic have shown temperatures that were previously considered impossible for the Arctic Circle. In addition, a notable correlation of the warm periods in the Arctic with large melting events in Antarctica points to previously unknown interactions between the Polar Regions. This is the conclusion of an international research team under participation of PD Dr. Norbert Nowaczyk, Section 5.2 Climate Dynamics and Landscape Evolution at the GFZ, in the journal "Science", published at the 20 July 2012.
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Climatic effects of a solar minimum
A grand solar minimum and the climate response recorded for the first time in the same climate archive highlights the need for a more differentiated approach to solar radiation.
Celia Martin-Puertas, Katja Matthes, Achim Brauer et al. (2012): Regional atmospheric circulation shifts induced by a grand solar minimum, Nature Geoscience, DOI 10.1038/NGEO1460
Nature Journal, May 2012: An abrupt cooling in Europe together with an increase in humidity and particularly in windiness coincided with a sustained reduction in solar activity 2800 years ago. Scientists from the Section 5.2 Climate Dynamics and Landscape Evolution and Section 1.3 at the GFZ in collaboration with Swedish and Dutch colleagues provide evidence for a direct solar-climate linkage on centennial timescales. Using the most modern methodological approach, they analysed sediments from Lake Meerfelder Maar, a maar lake in the Eifel/Germany, to determine annual variations in climate proxies and solar activity.