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Climate of the Past An interactive open-access journal of the European Geosciences Union
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
02 Oct 2013
Review status
This discussion paper is a preprint. It has been under review for the journal Climate of the Past (CP). A final paper in CP is not foreseen.
Cumulated insolation: a simple explanation of Milankovitch's forcing on climate changes
F. Marra Istituto Nazionale di Geofisica e Vulcanologia, Dept. Seismology and Tectonophysics, Via di Vigna Murata 605, 00147 Rome, Italy
Abstract. The occurrence of the sudden melting of the ice sheets during the glacial terminations is explained in this paper as the consequence of the combined role of the minima and the maxima of mean summer insolation on the Northern Hemisphere, providing a new contribution to understand the mechanisms ruling glacial forcing. Indeed, no satisfactory answer has been provided so far to the question why one specific maximum, after a series of consecutive maxima of insolation, has the potentiality to trigger a deglaciation. The explanation proposed in this paper accounts for a pre-conditioning factor, represented by "mild" (warmer) minimum, followed by a sufficiently warm maximum as the conditions that cause the end of a glacial cycle. These conditions are realized whenever the sum of the values of each consecutive minima and maxima ("cumulated insolation") on the curve of mean summer insolation at 65° N exceeds 742 Watt m−2. The comparison of the succession of these cumulated insolation values with the astronomically tuned Oxygen isotopes record provides a satisfactory match with the occurrence of all the glacial terminations in the last 800 ka.

Citation: Marra, F.: Cumulated insolation: a simple explanation of Milankovitch's forcing on climate changes, Clim. Past Discuss., 9, 5553-5568,, 2013.
F. Marra
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC C2643: 'Comment on the simulation of terminations.', Anonymous Referee #1, 21 Nov 2013 Printer-friendly Version 
AC C2701: 'reply to reviewer 1', Fabrizio Marra, 27 Nov 2013 Printer-friendly Version Supplement 
RC C2674: 'Nothing significant', Anonymous Referee #2, 26 Nov 2013 Printer-friendly Version 
AC C2702: 'Reply to reviewer 2', Fabrizio Marra, 27 Nov 2013 Printer-friendly Version 
F. Marra
F. Marra


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