HR: 08:15h
AN: PP31C-02 INVITED     [Abstracts]
TI: Regional and Temporal Differences in Abrupt Climate Change Recorded in Greenland Ice
AU: * Popp, T J
EM: trevor.popp@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, CB 450, Boulder, CO 80309 United States
AU: White, J W
EM: james.white@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, CB 450, Boulder, CO 80309 United States
AU: Johnsen, S J
EM: sigfus@gfy.ku.dk
AF: Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark, Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AU: Jouzel, J
EM: jouzel@lsce.saclay.cea.fr
AF: Institute Pierre Simon Laplace/ Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS, CE Saclay, Omme des Merisiers, Gir-Sur-Yvette, 91191 France
AU: Masson-Delmotte, V
EM: masson@lsce.saclay.cea.fr
AF: Institute Pierre Simon Laplace/ Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS, CE Saclay, Omme des Merisiers, Gir-Sur-Yvette, 91191 France
AU: Steffensen, J P
EM: jps@gfy.ku.dk
AF: Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark, Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AB: Detailed temporal and spatial examination of the processes, propagation, and variability of abrupt climate changes recorded in Greenland ice is now possible due to the availability of several deep Greenland ice cores coupled with the routine measurement of annually or better resolved proxy data. Greenland ice cores are uniquely suited for study of past abrupt climate events because relatively high snow accumulation rates allow single years to be identified well into the last glacial period. To more fully exploit the temporal and spatial resolution available in Greenland ice, here we present ice stable isotope measurements (oxygen-18 and deuterium) across the entire deglacial transition and several Dansgaard-Oeschger events in the NorthGRIP ice core with near-annual resolution, as well as several of these same climate transitions in GISP2 ice with similar detail. In both ice cores, calculated deuterium excess time series consistently show that the deuterium excess transitions occur in a single rapid step of less than a decade and are generally more abrupt than the corresponding isotopic transition. To assess regional character of abrupt climate change, we use deuterium excess transitions, in conjunction with volcanic signals, as reference points to cross date the ice cores. Once aligned, examination of the common variance of the NGRIP and GISP2 isotopic and deuterium excess time series shows remarkable coherence in one or both of the parameters in many of the finest details. This indicates that additional interpretable climate information is available with these detailed measurements and that each event may have some unique character. For example, NGRIP and GISP2 share a very similar deuterium excess transition at time around the Bolling warming, but the corresponding isotopic shifts between the two cores are markedly different. In contrast, at the end of the Younger Dryas, NGRIP and GISP2 isotopic shifts are very similar while the deuterium excess series share a sharp shift but are otherwise less similar. Meanwhile, the shape of isotopic transitions, accumulation rate patterns, and timing of climate changes relative to a suite of chemical species changes in the ice can vary from one abrupt event to the next. The emerging picture illustrates that not all abrupt climate transitions may be regionally uniform across Greenland, nor can any single sequence of events describe all abrupt climate changes, thus reducing their predictability. In the absence of a typical abrupt transition, we discuss possible forcing mechanisms in the context of different environmental boundary conditions related to ice volume, insolation, and Heinrich Events.
DE: 0724 Ice cores (4932)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005