under a Creative Commons License. Climate of the Past Discussions Interactive comment on “Ice-driven CO2 feedback

• Main Author: M. Mudelsee (referee
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2006
• Subjects: EGU; EPICA; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.482.7362; http://www.cosis.net/copernicus/EGU/cpd/2/S35/cpd-2-S35.pdf?PHPSESSID=970f14118aefecc68cd6fd1015681fbe

General comments I agree with the author’s first sentence that "the origin of the major ice-sheet variations during the last 2.7 million years remains a mystery. " Milankovitch’s proposal that Earth orbital variations influence Pleistocene ice-volume variations is certainly helpful. From the papers on the detection of Milankovitch variability in climate records (many of which cited in the present manuscript), several are milestones in the development of a theory of Pleistocene climate evolution. Before such a theory is wide and accurate enough to be accepted by the community, however, several empirical problems and inconsis-tencies should be removed. The present manuscript attacks some of those, such as the role of orbital-scale changes in atmospheric greenhouse-gas concentrations, the stage-11 problem, the 100-kyr problem and what might be termed the EPICA problem, namely that glacial-interglacial amplitudes in several climate variables increased after marine isotope stage 11.