About 10% of the land surface are underlain by permafrost, with important implications for the local carbon-, water- and energy-cycles. The permafrost extent is highly sensitive to shifts in temperature, thus, it has and will continue to change in the future. With most ecosystem processes being affected by the presence of permafrost, these changes entail feedback effects not only on local- but also on the large-scale climate. Here, the focus has chiefly been on the biochemical feedbacks, such as the permafrost-carbon feedback, but there is also a potential for (bio-) physical feedback mechanisms. The degradation of permafrost may affect the land-atmosphere moisture exchange through its impact on the surface hydrology, which in turn shapes the local and regional cloud cover. Vegetation shifts affect surface -albedo, -roughness and resistance to evaporation, with a similar potential to modify land atmosphere interactions. They may also modify fire frequency and -intensity, affecting cloud formation rates through the release of aerosols, which act as cloud condensation nuclei.

The above examples do not constitute a complete list and we welcome all abstracts focusing on any physical, biophysical and biochemical permafrost-climate feedback, explicitly including submissions proposing novel mechanisms. We encourage contributions that aim at a quantification of the feedback strengths, at the regional to global scale, and those which improve our understanding of mechanisms, at the process-level. Likewise, we welcome abstracts targeting feedback mechanisms under scenario-based future projections as well during the historical period and in the deeper past. Contributions relying on modelling tools and observational data are equally welcome and so are submissions conceptually describing feedback-chains that have been overlooked by the scientific community.