Home›Open Questions›What caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?Open QuestionsWhat caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?Citation FormatsGeneral ReferenceGeneral Reference Citation TextEarth and Environment Atlas. "What caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?." Accessed August 30, 2026. https://earth.interactiveatlas.org/open-questions-index/mid-pleistocene-transition-cause.Copy General ReferenceAPA StyleAPA Style Citation TextEarth and Environment Atlas. (n.d.). What caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?. Retrieved August 30, 2026, from https://earth.interactiveatlas.org/open-questions-index/mid-pleistocene-transition-causeCopy APA StyleBibTeXBibTeX Citation Text@misc{earthandenvironmentatlas-what-caused-the-mid-pleistocene-transiti, author = {Earth and Environment Atlas}, title = {What caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?}, year = {2026}, url = {https://earth.interactiveatlas.org/open-questions-index/mid-pleistocene-transition-cause}, note = {Accessed August 30, 2026} }Copy BibTeXReference and ClassificationDevelopingFactsOpen QuestionCross-Tradition ConnectionsSourcesComments (0)Reader Challenges (0 open reader challenges)FactsWhy OpenWell-attestedMilankovitch cycles predict a strong 41,000 year obliquity signal throughout, yet ice core and marine sediment records show glacial cycling shifted toward a dominant 100,000 year period around one million years ago, a change the orbital forcing itself does not obviously explain, since the eccentricity cycle it would need to track is a comparatively weak driver of incoming solar radiation on its own. 1What Would ResolveWell-attestedA mechanism, most proposed candidates involve declining atmospheric carbon dioxide, thinning regolith on the continents changing how ice sheets respond, or some combination, that can be tested against the same ice core and sediment record well enough to be preferred over its rivals rather than merely consistent with the data. 1Discipline NeededWell-attestedClimatology, Geochronology 1Open QuestionMilankovitch cycles predict a strong 41,000 year obliquity signal throughout, yet ice core and marine sediment records show glacial cycling shifted toward a dominant 100,000 year period around one million years ago, a change the orbital forcing itself does not obviously explain, since the eccentricity cycle it would need to track is a comparatively weak driver of incoming solar radiation on its own.What would resolve this A mechanism, most proposed candidates involve declining atmospheric carbon dioxide, thinning regolith on the continents changing how ice sheets respond, or some combination, that can be tested against the same ice core and sediment record well enough to be preferred over its rivals rather than merely consistent with the data.OpenClimatology, GeochronologyGeologic Time Scale (Wikipedia)Cross-Tradition ConnectionsQuestion OnPleistocene, Eras Well-attested Source Geologic Time Scale (Wikipedia)Sources1. Geologic Time Scale (Wikipedia)Wikimedia FoundationApproximately one million years ago, cycle-length shiftView the SourceComments (0)No comments yet. Be the first to share a thought.Sign in to join the discussion.Reader Challenges (0 open reader challenges)No disputes yet. Spotted an error or a better source? Open the first one.Sign in to dispute this or suggest a correction.View At A Past YearThe atlas records no dated fact of its own for this entry, so there is no other year to choose.Show This Year