Long-term changes in vegetation thermal insulation for characteristic permafrost-affected landscapes of Arctic Alaska

Keywords: Permafrost, Active Layer, Tundra, Snow, Thermal Regime
Abstract Type: Poster Abstract

Abstract

Accelerated climatic warming in the high northern latitudes has led to profound effects on the permafrost system. Warming and related thawing of permafrost can negatively affect Arctic communities, disrupt normal environmental conditions, and cause further warming through greater release of greenhouse gasses. However, the climatic signal is greatly modified by the natural ground covers (e.g vegetation and snow) contributing to the spatially and temporally variable response of permafrost to atmospheric forcing. Empirical and modeling studies agree that Arctic vegetation changes are causing contrasting feedbacks and nonlinear effects on permafrost. Thicker vegetation can favor ground cooling and preserve permafrost by providing insulation and summer shading, while denser or taller vegetation can warm and degrade permafrost by lowering albedo and trapping winter snow. Here we present 25 years of air and ground surface (below vegetation) temperature observations collected by the Circumpolar Active Layer Monitoring (CALM) program at an array of sites, representative of tundra land-cover classes in Arctic Alaska. The analysis is focused on a quantitative assessment of long-term changes in seasonal insulating properties of tundra vegetation classes. Results reveal that different plant communities exhibit distinct changes in insulating properties, which can partially explain the varied, and in some instances divergent trends in permafrost responses under similar climate conditions. This research contributes to the understanding of climate-vegetation-permafrost interactions for assessing the sensitivity of permafrost landscapes to climatic variability and change. The findings provide valuable empirical data for validating complex climate and ecosystem models across the Arctic.