Permafrost Cloud Feedback May Amplify Climate Change

• Published in: Geophysical Research Letters
• Main Authors: Philipp deVrese, Tobias Stacke, Veronika Gayler, Victor Brovkin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: permafrost; hydrology; clouds; climate change; Geophysics. Cosmic physics; QC801-809
• Online Access: https://doi.org/10.1029/2024GL109034; https://doaj.org/article/c308ed57cc0b4165a677e30370128c3f

Abstract Rising temperatures entail important changes in the soil hydrologic processes of the northern permafrost zone. Using the ICON‐Earth System Model, we show that a large‐scale thaw of essentially impervious frozen soil layers may cause a positive feedback by which permafrost degradation amplifies the causative warming. The thawing of the ground increases its hydraulic connectivity and raises drainage rates which facilitates a drying of the landscapes. This limits evapotranspiration and the formation of low‐altitude clouds during the snow‐free season. A decrease in summertime cloudiness, in turn, increases the shortwave radiation reaching the surface, hence, temperatures and advances the permafrost degradation. Our simulations further suggest that the consequences of a permafrost cloud feedback may not be limited to the regional scale. For a near‐complete loss of the high‐latitude permafrost, they show significant temperature impacts on all continents and northern‐hemisphere ocean basins that raise the global mean temperature by 0.25 K.