Differences between the glacial cycles of Antarctic temperature and greenhouse gases
A. W. Omta
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02130, USA
Received: 15 Feb 2012 – Accepted for review: 15 Mar 2012 – Discussion started: 27 Mar 2012
Abstract. Ice-core measurements have indicated that the atmospheric concentrations of the greenhouse gases CO2 and CH4 show glacial-interglacial variations in step with Antarctic temperature. To obtain more insight into the nature of this relationship for cycles of different frequencies, measured time series of temperature, CO2, and CH4 are reanalysed. The results indicate that the temperature signal consists of a linear superposition of a component related to CO2 with a period of ~100 000 yr and a component related to variations in the obliquity of the Earth's orbital plane with a period of ~41 000 yr. This suggests that either there operate very different feedback mechanisms at the different time scales or that CO2 is not merely a~passive follower and amplifier of the glacial-interglacial variations in Antarctic temperature.
Omta, A. W.: Differences between the glacial cycles of Antarctic temperature and greenhouse gases, Clim. Past Discuss., 8, 987-1004, doi:10.5194/cpd-8-987-2012, 2012.