Climate of the Past www.clim-past.net 1814-9324 1814-9332 3 1 2007 10.5194/cp-3-129-2007 http://www.clim-past.net/3/129/2007/ http://www.clim-past.net/3/129/2007/cp-3-129-2007.html http://www.clim-past.net/3/129/2007/cp-3-129-2007.pdf 129 134 2007-02-28 The DO-climate events are probably noise induced: statistical investigation of the claimed 1470 years cycle P. D. Ditlevsen pditlev@gfy.ku.dk K. K. Andersen A. Svensson The Niels Bohr Institute, Department of Geophysics, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark The significance of the apparent 1470 years cycle in the recurrence of the Dansgaard-Oeschger (DO) events, observed in the Greenland ice cores, is debated. Here we present statistical significance tests of this periodicity. The detection of a periodicity relies strongly on the accuracy of the dating of the DO events. Here we use both the new NGRIP GICC05 time scale based on multi-parameter annual layer counting and the GISP2 time scale where the periodicity is most pronounced. For the NGRIP dating the recurrence times are indistinguishable from a random occurrence. This is also the case for the GISP2 dating, except in the case where the DO9 event is omitted from the record. Alley, R B., Shuman, C A., Meese, D A., Gow, A J., Taylor, K C., Cuffey, K M., Fitzpatrick, J J., Grootes, P M., Zielinski, G A., Ram, M., Spinelli, G., and Elder, B.: Visual-stratigraphic dating of the GISP2 ice core: Basis, reproducibility and application, J. Geophys. Res., 102, 26 367–26 381, 1997. Alley, R B., Anandakrishnan, S., and Jung, P.: Stochastic resonance in the North Atlantic, Paleoceanography, 16, 190–198, 2001. Andersen, K K., Svensson, A., Rasmussen, S O., Steffensen, J P., Johnsen, S., Bigler, M., Röthlisberger, R., Ruth, U., Siggaard-Andersen, M.-L., Dahl-Jensen, D., Vinter, B M., and Clausen, H B.: The Greenland Ice Core Chronology 2005, 15–42 ka. Part 1: Construction of the time scale, QSR Shackleton special edition, 25, 3246–3257, 2006. Benzi, R., Parisi, G., Sutera, A., and Vulpiani, A.: Stochasic resonance in climate change, Tellus, 34, 10–16, 1982. Braun, H., Christi, M., Rahmstorf, S., Ganopolski, A., Mangini, A., Kubatski, C., Roth, K., and Kromer, B.: Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model, Nature, 438, 208–211, 2005. Dansgaard, W., Johnsen, S J., Clausen, H B., Dahl-Jensen, D., Gundestrup, N S., Hammer, C U., Hvidberg, C S., Steffensen, J P., Sveinbjornsdottir, A E., Jouzel, J., and Bond, G.: Evidence for general instability of past climate from a 250-kyr ice-core record, Nature, 364, 218–220, 1993. Ditlevsen, P D., Kristensen, M S., and Andersen, K K.: The recurrence time of Dansgaard-Oeschger events and limits on the possible periodic component, J. Climate, 18, 2594–2603, 2005. Grootes, P M. and Stuiver, M.: Oxygen 18/16 variability in Greenland snow and ice with $10^-3$- to $10^5$-year time resolution, J. Geophys. Res., 102, 26 455–26 470, 1997. Huybers, P. and Wunsch, C.: Obliquity pacing of the late Pleistocene glacial terminations, Nature, 434, 491–494, 2005. Johnsen, S J., Dahl-Jensen, D., Gundestrup, N., Steffensen, J P., Clausen, H B., Miller, H., Masson-Delmotte, V., Sveinbjørnsdottir, A E., and White, J.: Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland and NorthGRIP, J. Quat. Sci., 16, 299–307, 2001. Meese, D A., Gow, A J., Alley, R B., Zielinski, G A., Grootes, P M., Ram, M., Taylor, K C., Mayewski, P A., and Bolzan, J F.: The Greenland Ice Sheet Project 2 depth-age scale: Methods and results, J. Geophys. Res., 102, 26 411–26 423, 1997. Muscheler, R. and Beer, J.: Solar forced Dansgaard/Oeschger events?, Geophys. Res. Lett., 33, L20706, doi:10.1029/2006GL026779, 2006. North GRIP members: High resolution Climate Record of the Northern Hemisphere reaching into the last Glacial Interglacial Period, Nature, 431, 147–151, 2004. Rahmstorf, S.: Timing of abrupt climate changes: A precise clock, Geophys. Res. Lett., 30, 1510–1514, 2003. Schulz, M.: On the 1470-year pacing of Dansgaard-Oeschger warm events, Paleoceanography, 17, doi:1029/200PA000571, 2002. Svensson, A., Andersen, K K., Bigler, M., Clausen, H B., Dahl-Jensen, D., Johnsen, S., Muscheler, R., Rasmussen, S O., Röthlisberger, R., Steffensen, J P., and Vinter, B M.: The Greenland Ice Core Chronology 2005, 15–42 ka. Part 2: Comparison to other records, QSR Shackleton special edition, 25, 3258–3267, 2006. Wunsch, C.: On sharp spectral lines in the climate record and the millennial peak, Paleoceanography, 15, 417–424, 2000.