100 kyr ice age cycles as a timescale-matching problem

<p>The dominant period of the Late Pleistocene glacial–interglacial cycles is roughly 100 <span class="inline-formula">kyr</span>, rather than other major astronomical periods such as 19, 23, 41, and 400 <span class="inline-formula">kyr</span>. Various models explain this fact through distinct dynamical mechanisms, including synchronization of self-sustained oscillations and resonance in mono- or multi-stable systems. However, the diversity of proposed models and dynamical mechanisms may obscure the essential factor behind the emergence of the <span class="inline-formula">∼100</span> <span class="inline-formula">kyr</span> periodicity. We propose the hypothesis that the ice-sheet climate system responds to astronomical forcing at the <span class="inline-formula">∼100</span> <span class="inline-formula">kyr</span> periodicity because the intrinsic timescale of the system is closer to 100 <span class="inline-formula">kyr</span> than to other major astronomical periods. We support this idea with analyses and sensitivity studies of several simple ice age models with contrasting mechanisms.</p>