Topographies Seminar Series Presents: “Nonlinear feedbacks in glacier response to climate change”

• In-person event
• A220, Loeb Building, Carleton University
• 1125 Colonel By Drive, Ottawa, ON, K1S 5B6

• Contact
• Nika Linseman, nika.linseman@carleton.ca

Dr. Shawn Marshall, 
Research Scientist and  Chief Science Officer
Environment and Climate Change Canada    

Abstract
Glaciers worldwide are experiencing accelerated mass loss in recent decades, at rates that exceed what is expected from just the effects of climate warming. Changes have been dramatic in western Canada, where the rate of glacier thinning has doubled since 2020, relative to the prior decade (Menounos et al., 2025). The accelerated thinning is indicative of positive feedbacks to glacier retreat, nonlinear processes, or additional climate forcing beyond just the direct effects of warming. It is probably all of the above, but I will discuss different nonlinear and feedback processes that help to explain the glacier response in western Canada, including model experiments that help to isolate and identify what is driving recent observed changes. Much of the acceleration can be explained by albedo reductions, i.e., darkening of the glaciers, driven by both melt feedbacks and by the widespread deposition of impurities and organic carbon from wildfires.   

Biography
Shawn Marshall is a research scientist with Environment and Climate Change Canada (ECCC), where he studies glacier-climate processes and the representation of glaciers in hydrological and climate models.  Dr. Marshall joined ECCC in 2019, following a research career as a glaciologist and Canada Research Chair in Climate Change at the University of Calgary. He combines modelling and field studies at research sites in the Rockies, Arctic Canada, and Greenland to advance understanding of glacier response to climate change. Dr. Marshall is an Adjunct Research Professor in the Department and is looking forward to collaborative opportunities studying Arctic cryosphere and climate change.  

Topographies Seminar Series
Topographies is the Geography and Environmental Studies Seminar Series. Speakers are invited to present their research to an audience of graduate students, faculty, and other interested affiliates, on topics related to one of our various fields: environmental and climate change studies; human or physical geography; and geomatics.

We were drawn to the name Topographies as it works both materially (as arrangements of physical or natural features on the surface of the Earth, represented on a map or chart) and metaphorically (as aspects or nuances of an idea or theory). Formerly the Founders Seminar (2000-2024), named in honour of founding departmental members from the 1950s, ‘60s, and ‘70s, Topographies represents the next chapter of our efforts to build a community of scholars.

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