PErmafrost and Greenhouse gas dynamics in Siberia

Permafrost (permanently frozen ground) occupies more than 20 million square kilometres, representing nearly a quarter of the land surface in the northern hemisphere. In the circumpolar regions of the Earth, temperatures have recently risen three to four times as fast as the global average, a trend that is expected to continue during the 21st century. Climate warming results in a series of profound environmental impacts across Arctic regions, including permafrost thawing and erosion and the formation of ‘thermokarst’ lakes. This in turn releases organic carbon (formerly trapped in frozen soils) to the surface and may lead to increasing greenhouse gas (GHG) emissions to the atmosphere, ultimately enhancing warming. The main goal of the PEGS project (PErmafrost and Greenhouse gas dynamics in Siberia) is to quantify fluxes, sources and ages of GHGs (CO₂, CH₄) emitted from representative thermokarst lakes of Central Yakutia (Siberia) in response to permafrost degradation, at different spatial and temporal scales. It combines multiple tools and techniques and integrates field-based, laboratory and local-scale modelling investigations in order to tackle key questions in Earth System sciences, specifically concerning the Arctic system. The project’s main outcomes include: i) the characterization of GHG fluxes from lakes in central Yakutia, among the highest across the Arctic; ii) a paleo-environmental reconstruction of organic carbon dynamics during the last 14,000 years based on sediment core analysis; iii) the development of an automated mapping approach for quantifying lake surface areas based on machine learning. The main results of the project will help refining Earth system models with real field data.