Limited control of microtopography evolution on ground subsidence in polygonal tundra landscapes

Rapid surface and subsurface changes in the Arctic polygonal tundra landscapes due to the melting of ice wedges, known as thermokarst processes, have significant implications for Arctic ecosystems. However, the integration of thermokarst processes into widely used global climate models for projections poses an important question. Here we use an integrated permafrost thermal hydrology model to explore the decoupled nature of two thermokarst processes - microtopography evolution and ground subsidence - in six Arctic locations. Our study specifically investigates this decoupled nature during the transformation of poorly drained low-centered polygons to well-drained high-centered polygons. Spanning diverse climates in polygonal tundra landscapes under the RCP8.5 climate scenario, our findings reveal small variations in permafrost thaw and ground subsidence rates - 2-10 % and 2-4 %, respectively - with and without the representation of microtopography evolution. This suggests that neglecting surface microtopography and its evolution is unlikely to have significant impacts on permafrost projections, regardless of the climate and location. As a result, we suggest the representation of microtopography in Earth System Models may not be imperative. Disclaimer: Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration.