Permafrost Thaw Emerges as Key Driver of Arctic Erosion

A new study in Proceedings of the National Academy of Sciences highlights how the overlapping effects of sea level rise, permafrost thaw subsidence and coastal erosion could result in unprecedented land loss along Arctic coastlines. Researchers from the Woods Hole Oceanographic Institution (WHOI) and other institutions emphasize that these combined hazards could drive coastal changes far beyond the impacts of any single factor.

Alaska’s Arctic Coastal Plain under threat

The study focuses on Alaska’s Arctic Coastal Plain (ACP), a low-elevation region spanning over 60,000 square kilometers. Characterized by ice-rich permafrost, the ACP experiences some of the Arctic’s fastest rates of sea level rise and coastal erosion. These processes, combined with subsidence from thawing permafrost, are accelerating land loss and pushing coastlines inland.

By 2100, these combined effects are expected to move the North Slope shoreline to a position not seen since the last interglacial period over 100,000 years ago. The researchers warn that this rapid transformation requires immediate attention to safeguard vulnerable communities and infrastructure.

Coastal land loss: A paradigm shift

While coastal erosion has been extensively documented, this study integrates additional factors such as subsidence caused by permafrost thaw and sea level rise. Using data from high-resolution topography, satellite-derived coastal lake depths and projections from the IPCC’s 6th Assessment Report, the researchers estimate that total land loss could exceed erosion-related losses by up to eight times under medium- and high-emission scenarios.

“Along ice-rich permafrost coastlines, the land surface is falling faster than the sea levels are rising. Over the coming decades, permafrost thaw subsidence will move the coastline farther inland than coastal erosion or sea level rise alone will move it, and this subsidence will dominate Arctic coastal change over the long term,”

Dr. Pier Paul Overduin

Implications for Arctic communities

The loss of Arctic land has profound implications for local communities. Disappearing coastlines threaten infrastructure, subsistence access routes, cultural heritage sites and hunting grounds. The researchers stress the need for adaptive planning that considers the cumulative effects of multiple climate hazards.

Study lead author Dr. Roger Creel, a postdoctoral scholar in WHOI’s Department of Physical Oceanography said the impact of permafrost thaw subsidence is familiar to people who live in northern Alaska. However, he adds agencies such as the U.S. Army Corps of Engineers and the Federal Emergency Management Agency allocate many of their resources based on published literature.

“These sorts of bodies with a lot of resources may have not been paying enough attention to permafrost thaw subsidence as an agent of coastal change. This study is a wake-up call to expand the conversation,” said Creel.

A collaborative approach to coastal resilience

The study highlights the importance of interdisciplinary collaboration for robust projections of Arctic coastal evolution. Co-author Julia Guimond from WHOI emphasized that findings from Alaska’s ACP are relevant to coastal resilience planning globally. Understanding the interplay of climate hazards is crucial for preparing communities to adapt to the rapid changes projected in the 21st century.

Reference: Creel R, Guimond J, Jones BM, et al. Permafrost thaw subsidence, sea-level rise, and erosion are transforming Alaska’s Arctic coastal zone. Proc Natl Acad Sci USA. 2024;121(50):e2409411121. doi: 10.1073/pnas.2409411121

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