Transformative Effects of Climate Change on Arctic River Systems

Transformative Effects of Climate Change on Arctic River Systems

Photographic and topographical data from Axel Heiberg Island, near Expedition Fjord, exhibit significant alterations. Acknowledgments: Shawn Chartrand

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Over six decades, escalated global warming has fundamentally altered the river networks in Canada’s High Arctic, driven by cyclical freezing and thawing patterns as well as changes in flooding behavior. Recent studies highlight the immediate necessity for computational models to anticipate future environmental transitions in the Arctic.

The joint research effort between Simon Fraser University and the University of British Columbia reveals that accelerated climate change has induced a dramatic restructuring of river systems etched into permafrost terrains within a 60-year timeframe. The research identifies intricate interactions among climate variations, ground freeze-thaw cycles of polygonal formations, and water dispersal due to flooding, snowmelt, and ice melt. This has led to a novel understanding of the physical mechanisms that dictate the rate and configuration of river channel evolution in these vulnerable ecosystems.

Polygonal Terrain and Fluid Dynamics

Shawn Chartrand, an assistant professor in the School of Environmental Science at Simon Fraser University and the primary author of the research, which is published in today’s issue of the journal Nature Communications, states, “The developmental trajectory of stream networks is governed by how water navigates through approximately 10-meter wide polygonal fields formed due to the cyclical freezing and thawing of Arctic soil.”

“This governing dynamic is further modulated by the timing, amplitude, and duration of flood events, as well as the state—whether frozen or partially thawed—of the foundational sediment particles.”

Antero Kukko was responsible for collecting elevation data using the AkhkaR4DW mobile laser scanning system, a device he engineered. Acknowledgments: Shawn Chartrand

Investigative Approach and Landscape Transformation

Chartrand is part of an international collective of researchers who initiated their fieldwork on Axel Heiberg Island, coinciding with one of the most severe instances of summertime warming ever recorded. The team utilized aerial imagery from 1959, ground-level observations, and cutting-edge Light Detection and Ranging (LiDAR) data gathered in 2019 to analyze the landscape transformations of Axel Heiberg Island over a span of 60 years.

Climate Change’s Chain Reactions

Mark Jellinek, co-author of the study and a professor in the Department of Earth, Ocean, and Atmospheric Sciences at the University of British Columbia, says, “Synergistic physical phenomena can deepen and broaden river networks, thereby increasing the surface area available for heat exchange. This has the potential to accelerate local permafrost thaw rates, which in turn can escalate the release of greenhouse gases as organic soil carbon melts and permafrost recedes.”

The researchers used LiDAR data to generate a Digital Elevation Model (DEM) covering a 400-meter section of the Muskox Valley. Chartrand adds, “Our hydrological models indicated that floodwaters channeled through connected polygonal troughs increase the propensity for erosion and river channel formation.”

Thermal Influences on Flooding Behavior

Water from valley lakes, along with seasonal melting of snow and ground ice, coalesce in the valley, creating conditions conducive for the transportation of coarse sediment and the formation of river channels. Timing of these floods, especially during peak thaw seasons, can significantly impact the extent of erosion. Chartrand elaborates, “Ambient air temperature is a factor. We theorize that the erosive force and sediment transport are susceptible to the timing of floods in relation to periods of elevated temperatures, as this determines the depth to which sediment layers are thawed and hence are transportable by floodwaters.”

Forward Outlook: Anticipating Subsequent Developments

The researchers contend that the next challenge is the application of these findings to construct reliable physical models for forecasting how Arctic river systems will adapt in the coming decades, a period expected to witness both escalating temperatures and climate instability. The urgency is heightened due to the likelihood that expanding river networks will transport increased amounts of sediment, nutrients, and metals into delicate watersheds, with potentially critical repercussions for coastal ecosystems, water quality, and human communities.

Publication Date: September 12, 2023, Nature Communications.
DOI: 10.1038/s41467-023-40795-9

The investigative team also incorporated experts from the Finnish Geospatial Research Institute, Laboratoire de Planétologie et Géosciences (UMR CNRS 6112), University of Western Ontario, and the Jet Propulsion Laboratory.

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More about Arctic River Evolution

• Simon Fraser University
• University of British Columbia
• Nature Communications
• Finnish Geospatial Research Institute
• Laboratoire de Planétologie et Géosciences
• University of Western Ontario
• Jet Propulsion Laboratory