The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles Potsdam Institute for Climate Impact Research, Potsdam, Germany
14 Dec 2011
Received: 24 June 2011 – Published in Clim. Past Discuss.: 18 July 2011 Abstract. The origin of the 100 kyr cyclicity, which dominates ice volume variations
and other climate records over the past million years, remains debatable.
Here, using a comprehensive Earth system model of intermediate complexity,
we demonstrate that both strong 100 kyr periodicity in the ice volume
variations and the timing of glacial terminations during past 800 kyr can be
successfully simulated as direct, strongly nonlinear responses of the
climate-cryosphere system to orbital forcing alone, if the atmospheric
CO2 concentration stays below its typical interglacial value. The
existence of long glacial cycles is primarily attributed to the North
American ice sheet and requires the presence of a large continental area
with exposed rocks. We show that the sharp, 100 kyr peak in the power
spectrum of ice volume results from the long glacial cycles being
synchronized with the Earth's orbital eccentricity. Although 100 kyr
cyclicity can be simulated with a constant CO2 concentration, temporal
variability in the CO2 concentration plays an important role in the
amplification of the 100 kyr cycles.
Revised: 27 October 2011 – Accepted: 28 October 2011 – Published: 14 December 2011
Citation: Ganopolski, A. and Calov, R.: The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles, Clim. Past, 7, 1415-1425, doi:10.5194/cp-7-1415-2011, 2011.