A new study in Earth's Future uses lake sediment cores to compare how landscapes erode under continuous versus discontinuous permafrost. The researchers sampled 12 lakes in Alaska—near Toolik in the north, where permafrost is mostly continuous, and near Delta Junction in the south, where it is patchier. By calculating sediment fluxes and erosion rates from the cores, they constrained a landscape evolution model to separate hillslope-driven diffusion from channel-driven advection.
The results show that diffusive, hillslope processes have been statistically more significant than advective, channel processes in both regions since the middle Holocene. More strikingly, the average intensity of those hillslope erosional processes was two to three times greater in discontinuous permafrost areas than in continuous ones. The authors caution that this difference may be specific to the study sites and call for similar work in other catchments.
Because the Arctic is warming about four times faster than the global average, continuous permafrost is expected to become more discontinuous in places. The findings imply that such transitions could bring significantly stronger hillslope erosion, with consequences for ecosystems, carbon release, and northern communities. The study helps fill a gap in models, which have often estimated these processes rather than measuring them directly at the catchment scale.