New scientific results for the Late Cretaceous greenhouse indicate radically different climatic mechanisms operating about 75-90 million years ago compared to the ones that control today’s climate. The study, published on 29 May 2006 in “Palaeogeography, Palaeoclimatology, Palaeoecology” as part of a special issue on “Causes and Consequence of Marine Organic Carbon Burial Through Time” by Sascha Floegel from the IFM-GEOMAR in Kiel/Germany and Thomas Wagner from the University of Newcastle upon Tyne/UK aims to identify the main ‘climate kitchen’ in a world with about 5-9°C warmer global temperatures than today.
The researchers focus their interest on the causal relationships and feedbacks between the tropics and higher latitudes. Using marine geological records and data from global paleoclimate simulations they identify a previously unrecognized link between higher latitude climate dynamics and tropical African climate, the latter leading to exceptionally high burial of organic carbon in the deep tropical Atlantic. Marine geological record show that enhanced burial of organic carbon in the deep sea was confined to short time envelops of about 5 thousand years that reoccurred over millions of years at a regular pattern (see Beckmann and co-workers, published 8 September 2005 in Nature 437).
Climate modelling is one key technique to identify and understand the larger-scale mechanisms that result in geological evidence. By varying one of Earth’s orbital parameters, the precession of the equinoxes, the modelling setup used in this study provides new insights to the dynamics of global climate during past greenhouse conditions. Accordingly, changes in the amount of energy approaching the top of the atmosphere, called “insolation”, finally triggered cyclic variations of the tropical water cycle in tropical Africa. Periods of enhanced precipitation and freshwater runoff then resulted in massive burial of organic carbon at the sea floor suggesting that processes in the atmosphere drive changes in the ocean. The remaining, fundamental question on the source area(s) where cyclic fluctuations in tropical water cycling and marine carbon burial were triggered was addressed using global climate simulation.
Professor Thomas Wagner | alfa
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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