Arctic landscapes, especially those underlain by permafrost, are threatened by climate warming and may degrade in different ways, including active layer deepening, thermal erosion, and development of rapid thaw features. Increased permafrost thaw could cause a feedback loop of global significance if its stored frozen organic carbon is re-introduced into the active carbon cycle as greenhouse gases, which accelerate warming and inducing more permafrost thaw and carbon release. This loop is called permafrost–carbon feedback, and as this effect is strengthening itself, it is called a positive feedback.
First calculations of the carbon pool size stored in permafrost estimated a small carbon inventory, based on the assumption that cold climate cause less productive vegetation cover and thus a small input of organic matter into the soil column.
Today, we know that syngenetic freezing of organic matter over a period of thousands of years sequestered and freeze-locked a large amount of carbon.
To assess the concern of a permafrost carbon feedback and to develop a better understanding of future permafrost-carbon dynamics, the PETA-CARB project aims at quantifying the amount, distribution, and vulnerability of deep permafrost soil organic carbon pools, as well as how rapidly permafrost thaw impacts these carbon pools on various spatial and temporal scale.