Date/Time
Date(s) - 05/02/2026
10:30 am - 11:30 am

Speaker: Kolja Kypke (University of Guelph)

Location: Hamilton Hall, Room 410 & Zoom
Zoom link: https://mcmaster.zoom.us/j/98308755554 (MathBio)

Title: Chaotic variability of ice sheets on millennial timescales

Abstract: The bulk of the Greenland ice sheet (GrIS) evolves over time according to slow shear flow, but areas of fast flowing ice, such as topographically confined outlet glaciers or large ice streams, represent a source of variability with a faster dynamic timescale. The discharge of ice through ice streams contributes a large amount to the total ice-sheet mass loss despite their relatively small spatial extent. Furthermore, ice streams have accelerated due to increased atmospheric and oceanic forcing, contributing up to 50% of the GrIS mass loss in the last decades.

An ice-sheet model study reveals the interaction of two ice streams which oscillate in a cycle of gradual build-up and sudden surging. This impacts the timing of the mass loss of the entire ice sheet under external temperature forcing in the form of chaotic transients. To test the mechanism responsible for these chaotic transients, a simplified model of two independent ice streams which are coupled via a shared upstream ice source is constructed. This model demonstrates that ice sheets can have a mode of purely temporal internal chaotic variability that acts on millennial timescales.

Dr. Kypke completed his PhD at the University of Copenhagen and is now a postdoctoral fellow at the University of Guelph.