Improving Sea Level Projections in Northern Alaska

Abstract

Modern day climate change is exacerbating sea level change both locally and globally. The magnitudes of these changes are dependent on numerous global and regional factors that make it difficult to accurately project local sea level into the future. In Alaska, there are many processes contributing to sea level changes along the coast. In particular, there is substantial vertical land movement, in the form of uplift and subsidence, due to the isostatic adjustment of the land once burdened by ice sheets. In Northern Alaska, there is an additional source of land motion that occurs because the flat, tundra landscape is underlain by ~100-300m of permafrost. This permafrost is currently melting and the area is experiencing land subsidence because of it. This study refines sea level projections along northern Alaska by accounting for this extra climate signal. The addition of permafrost-melt induced isotropic land subsidence in projections for the northern coast of Alaska results in sea level rise estimates at the end of the century that double previously published projections. These improved Alaska projections will be vital for the coastal communities, especially in coming decades, in order to minimize losses of coastal property and infrastructure.