The North American Cordillera-An impediment to growing the continent-wide laurentide ice sheet

Marcus Löfverström, Johan Liakka, Johan Kleman

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


This study examines the evolution of a continental-scale ice sheet on a triangular representation of North America, with and without the influence of the Cordilleran region. Simulations are conducted using a comprehensive atmospheric general circulation model asynchronously coupled to a three-dimensional thermomechanical ice-sheet model. The atmospheric state is updated for every 2 × 106 km3 increase in ice volume, and the coupled model is integrated to steady state. In the first experiment a flat continent with no background topography is used. The ice sheet evolves fairly zonally symmetric, and the equilibriumstate is continent-wide and has the highest point in the center of the continent. This equilibrium ice sheet forces an anticyclonic circulation that results in relatively warmer (cooler) summer surface temperatures in the northwest (southeast), owing to warm (cold) air advection and radiative heating due to reduced cloudiness. The second experiment includes a simplified representation of the Cordilleran region. The ice sheet's equilibrium state is here structurally different from the flat continent case; the center of mass is strongly shifted to the east and the interior of the continent remains ice free-an outline broadly resembling the geologically determined ice margin in Marine Isotope Stage 4. The limited glaciation in the continental interior is the result of warm summer surface temperatures primarily due to stationary waves and radiative feedbacks.

Original languageEnglish (US)
Pages (from-to)9433-9450
Number of pages18
JournalJournal of Climate
Issue number23
StatePublished - 2015
Externally publishedYes


  • Circulation/Dynamics
  • Coupled models
  • Ice loss/growth
  • Large-scale motions
  • Models and modeling
  • Physical Meteorology and Climatology
  • Rossby waves
  • Topographic effects

ASJC Scopus subject areas

  • Atmospheric Science


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