Event Chains

The event chain approach for investigating permafrost thaw aims at understanding and quantifying the contribution of dynamic thaw events to the long-term greenhouse gas emissions in the Arctic. With interlinked land, lake, coastal and offshore observations, three major hypotheses shall be addressed by MOSES event-driven field campaigns:

(1) Changing water surfaces due to intensified lake changes, sea level rise and coastal erosion lead to accelerated permafrost warming and thaw.

(2) Permafrost thaw events create pathways for gas migration and release and accelerate organic matter decay. This will make permafrost regions the dominant and rapidly increasing positive feedback to global climate change.

(3) Mapping and monitoring the temporal and spatial variability of greenhouse gas fluxes will demonstrate that changing pathways for gas migration determine the greenhouse gas contribution of Arctic permafrost to the atmosphere.

Event Chains
Schematic diagram of event chains triggered by permafrost thaw. As permafrost acts as an impermeable layer, it seals and thus prevents gas exchange between deeper sediment layers and the atmosphere/water. Thaw events in summer and massive permafrost degradation enable trapped gas to be mobilized and released, destabilizing fossil carbon pools (mainly CH4 as potent GHG) and increasing climate warming. Similarly, the warming of terrestrial and marine sediments will destabilize gas hydrates and, in this case, mobilize a fossil carbon source of rather unknown size. The thaw of permafrost makes previously frozen organic matter available for decomposition, causing direct release of CO2 or CH4 and the release of nutrients. These nutrients might cause eutrophication along the coast and the open ocean with unknown consequences to ecosystems, finally affecting fish stock. On land, thawing permafrost causes subsidence and is thus a direct threat to infrastructure stability; along the coasts, ongoing erosion on a massive scale transports nutrients into the oceans, changing ecosystems and the way they function. The use of both land and coastal areas will irreversibly change in the near future.