1Department of Earth Science, University of Bristol, Bristol, UK
2National Oceanography Centre, Southampton, Southampton, UK
3Centre for Ice & Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
4Climate and Environmental Physics and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Received: 14 Jan 2010 – Discussion started: 29 Jan 2010
Abstract. Millennial variability is a robust feature of many paleoclimate records, at least throughout the last several glacial cycles. Here we use the mean signal from Antarctic climate events 1 to 4 to probe the EPICA Dome C temperature proxy reconstruction through the last 500 ka for similar millennial-scale events. We find that clusters of millennial events occurred in a regular fashion over half of the time during this with a mean recurrence interval of 21 kyr. We find that there is no consistent link between ice-rafted debris deposition and millennial variability. Instead we speculate that changes in the zonality of atmospheric circulation over the North Atlantic form a viable alternative to freshwater release from icebergs as a trigger for millennial variability. We suggest that millennial changes in the zonality of atmospheric circulation over the North Atlantic are linked to precession via sea-ice feedbacks and that this relationship is modified by the presence of the large, Northern Hemisphere ice sheets during glacial periods.
Revised: 13 Apr 2010 – Accepted: 22 Apr 2010 – Published: 05 May 2010
Siddall, M., Rohling, E. J., Blunier, T., and Spahni, R.: Patterns of millennial variability over the last 500 ka, Clim. Past, 6, 295-303, doi:10.5194/cp-6-295-2010, 2010.