35-12 Constraining Last Glacial Maximum Climate in the Colombian Andes Using Glacier Evolution Modeling

Session: Ice sheets, glaciers, and landscapes, oh my! (Posters)

Poster Booth No.: 45

Presenting Author:

Joel Wilner

Authors:

Wilner, Joel A.¹, Kelly, Meredith A.², Doughty, Alice M.³, Galloway, Peter B.⁴, Morlighem, Mathieu⁵, Restrepo-Moreno, Sergio⁶, Bromley, Gordon⁷

(1) Department of Earth Sciences, Dartmouth College, Hanover, , (2) Department of Earth Sciences, Dartmouth College, Hanover, , (3) School of Earth and Climate Sciences, University of Maine, Orono, , (4) Department of Earth Sciences, Dartmouth College, Hanover, , (5) Department of Earth Sciences, Dartmouth College, Hanover, , (6) Departamento de Geociencias y Medio Ambiente, Universidad Nacional de Colombia, Medellín, , (7) Geography, University of Galway, Galway, ,

Abstract:

The tropics play a disproportionate role in regulating global climate variability, yet quantitative constraints on Last Glacial Maximum (LGM; ~26–19 ka) climate remain sparse in northern South America. The Páramo del Sol massif (also known as Páramo de Frontino; maximum elevation ~4000 m a.s.l.), located in the Western Cordillera of the Colombian Andes, contains paleoecological records extending to ~17 ka and well-preserved glacial landforms, making it a promising but understudied site for tropical paleoclimate reconstruction. However, the temperature, precipitation, and lapse rate conditions that governed glacier extent during the LGM and subsequent deglaciation remain poorly constrained. Here, we present an ensemble of 672 glacier evolution simulations for Páramo del Sol using a two-dimensional coupled ice-flow–energy-balance model. We simulate glacier growth to steady state while systematically varying paleo-temperature, paleo-precipitation, and paleo-lapse rate, quantifying the spatial misfit between modeled ice margins and mapped LGM moraines. We identify a band of climate conditions that minimize ice-moraine misfit (< 50 m), revealing a broad range of acceptable temperature–precipitation–lapse-rate combinations. Optimal fits occur with 20% drier and 8.1°C colder conditions than modern when using lapse rates similar to the modern (-5.8°C/km), or 20% drier and 7.1°C colder when using steeper lapse rates (-6.5°C/km). We additionally conduct transient deglaciation experiments to determine the climate perturbations required to retreat glaciers from steady-state LGM extents to interior positions constrained by ¹⁰Be cosmogenic exposure ages. These results refine quantitative bounds on LGM climate in the Colombian Andes and demonstrate a transferable framework for large parameter space exploration in glacier-based paleoclimate reconstructions.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.