Observationally Constrained Cloud Phase Unmasks Orbitally Driven Climate Feedbacks

Navjit Sagoo, Trude Storelvmo, Lily Hahn, Ivy Tan, James Danco, Bryan Raney, Anthony J. Broccoli

Research output: Contribution to journalArticlepeer-review


The mechanisms which amplify orbitally driven changes in insolation and drive the glacial cycles of the past 2.6 million years, the Pleistocene, are poorly understood. Previous studies indicate that cloud phase feedbacks oppose ice sheet initiation when orbital configuration supports ice sheet growth. Cloud phase was observationally constrained in a recent study and provides evidence for a weaker negative cloud feedback in response to carbon dioxide doubling. We observationally constrain cloud phase in the Community Earth System Model and explore how changes in orbital configuration impact the climate response. Constraining cloud phase weakens the negative high latitude cloud phase feedback and unmasks positive water vapor and cloud feedbacks (amount and optical depth) that extend cooling to lower latitudes. Snowfall accumulation and ablation metrics also support ice sheet expansion as seen in proxy records. This indicates that well-known cloud and water vapor feedbacks are the mechanisms amplifying orbital climate forcing.

Original languageAmerican English
Article numbere2020GL091873
JournalGeophysical Research Letters
Issue number6
StatePublished - Mar 28 2021

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


  • Paleoclimate
  • Pleistocene
  • cloud phase feedback
  • glacial-interglacials
  • mixed phase clouds


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