Source: Earth’s Future
The Arctic is warming 4 times faster than the rest of the globe, and scientists are racing to understand how that fact affects the region’s landscapes and ecosystems. Permafrost thaw is one of the most visible signs of climate change, with whole hillslopes of previously frozen ground slumping off and coastlines falling into the ocean. It’s disrupting ecosystems, releasing carbon, and threatening Indigenous communities in the far north.
But not all landscapes with permafrost are alike. Some have continuous permafrost, whereas others have discontinuous permafrost, in which only 50% to 90% of the landscape is underlain by permafrost.
Özpolat et al. explore differences in how continuous and discontinuous permafrost landscapes erode, focusing on two types of erosive processes: diffusive processes, which primarily move sediments on hillslopes, and advective processes, which primarily erode and transport sediments in channels. Although these processes are key for shaping landscapes, their relative magnitudes remain largely unquantified in permafrost regions; in the few models that incorporate these two processes, they are typically estimated rather than based on direct catchment-scale observations. Better understanding how these two processes vary across permafrost landscapes would help improve models of how the Arctic will respond to climate change.
In the new study, the researchers took sediment cores from 12 lakes in Alaska near Toolik in the north, with more continuous permafrost, and near Delta Junction in the south, with more discontinuous permafrost. The cores spanned the middle Holocene to the present, capturing a period when the climate and permafrost conditions in these areas were similar to their present conditions.
From those cores, they calculated sediment fluxes and erosion rates in the lake’s catchments, then used those rates to constrain the diffusive and advective components of a landscape evolution model. They found that in both study areas, diffusive, primarily hillslope processes were statistically more significant than advective processes, suggesting that diffusive processes have been more responsible for shaping the landscape since the middle Holocene. Importantly, in areas with discontinuous permafrost, the average intensity of those diffusive erosional processes was 2 to 3 times greater than in areas with continuous permafrost.
The authors caution that the intensity differences may be specific to the study sites and that similar work should be done in other catchments to further evaluate their results. But overall, the findings suggest that as warming shifts some landscapes from continuous toward discontinuous permafrost conditions, hillslope erosion could increase significantly. (Earth’s Future, https://doi.org/10.1029/2025EF007889, 2026)
—Rebecca Dzombak, Science Writer
