Download or read book Characterisation of Rapid Climate Changes Through Isotope Analyses of Ice and Entrapped Air in the NEEM Ice Core written by Myriam Guillevic and published by . This book was released on 2013 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analyses of ice drilled in the Greenland ice sheet have revealed the occurrence of rapid climatic instabilities during the last glacial period, known as Dansgaard-Oeschger (DO) events. The imprint of DO events is also recorded at mid to low latitudes in different archives of the northern hemisphere. A detailed multiproxies study of the sequence of these rapid instabilities is essential for understanding the climate mechanisms at play. In this thesis, we combine water isotopes (d18O, d-excess and 17Oexcess) and air in Greenland ic cores (markers of temperature changes d15N, of land productivity d18Oatm, and also concentration and isotopic composition of methane) to quantify regional temperature changes in Greenland, to characterize the reorganization of the hydrological cycle and to better understand the role of the biosphere in climate feedbacks and the sequences of climatic events. Finally, we develop a multiproxies approach to identify in polar ice cores the fingerprint of Heinrich events (layers of ice rafted debris in North Atlantic marine cores, deposited by icebergs melt, caused by the collapse of Northern hemisphere ice sheets). Most of the new data presented in this thesis were obtained from the NEEM ice core, NW Greenland, drilled in 2008-2011 in the frame of an international project led by the Centre for Ice an Climate, Denmark.