PERMTHAW · Permafrost thaw – decadal responses to climate change

Permafrost thaw – decadal responses to climate change

Permafrost soils contain approximately 1672 Petagram carbon (C), twice the amount of the current atmosphere, and constitute 50% of the world’s belowground C pool. Along with the current change in climate these high latitudinal soils experience increased temperatures, more than any other region, with permafrost degradation and change of ecosystem functions as a result. The thaw of permafrost releases ancient organic matter that has been stored in the frozen soils for centuries. Following microbial degradation, this organic matter can be released to the atmosphere as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), further influencing the climate systems. Changes in ecosystem type and function can further influence these fluxes. Thus, a changing climate leads to server alterations of the carbon (C) and nitrogen (N) balance in the Arctic and high altitude ecosystems. However, research up to today has mostly focused on the impact of permafrost thaw and the time horizon immediately following this degradation. This project aims to understand the future that lies ahead, following thaw and establishment of new non-permafrost ecosystems, and how the predicted climate variability will influence these soils on a decadal timescale. By using a natural occurring permafrost degradation transects, this project investigates how the C and N cycling changes following thaw. Moreover, by using laboratory incubation the project provided unique insights in how these cycles will respond to the changing climate long after the formation of ‘new’ ecosystems, giving a decadal perspective on permafrost thaw. The investigated natural permafrost thaw gradient used in this study provided contrasting result compared to the heavily investigated carbon-rich emission hotspots usually highlighted in climate change discussion. Our result indicated that with increased vegetation and change towards a shrub-dominated landscape these mineral-based soils significantly reduces the methane emission due to a reduction in the anaerobic environment in the surface soil and an increase in methane consumption in this part of the soil. Furthermore, the long-term decomposition of carbon in the deeper former permafrost soils remains at a low emission rate, attributing most of the C and N cycling to the surface layer where even the carbon sequestration balance the decomposition rates from the deeper soils.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз