ORIGINAL RESEARCH article
Sec. Cryospheric Sciences
Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.802157
Permafrost Base Degradation: Characteristics and
ORIGINAL RESEARCH article
Sec. Cryospheric Sciences
Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.802157
Permafrost Base Degradation: Characteristics and Unknown Thread With Specific Example From Hornsund, Svalbard
- 1Institute of Earth Sciences, University of Silesia, Sosnowiec, Poland
- 2Institute of Geography and Regional Development, University of Wroclaw, Wroclaw, Poland
Permafrost degradation is one of the most pressing issues in the modern cryosphere related to climate change. Most attention is paid to the degradation of the top of the active permafrost associated with contemporary climate. This is the most popular issue because in the subsurface part of it there is usually the greatest accumulation of ground ice in direct relation to the changes taking place. The melting of ground ice is the cause of the greatest changes related to subsidence and other mass-wasting processes. The degradation of the subsurface permafrost layer is also responsible for the increased emission of CO2 and methane. However, this is not a fully comprehensive look at the issue of permafrost degradation, because depending on its thickness, changes in its thermal properties may occur more or less intensively throughout its entire profile, also reaching the base of permafrost. These changes can degrade permafrost throughout its profile. The article presents the basic principles of permafrost degradation in its overall approach. Both the melting of the ground ice and the thermal degradation of permafrost, as manifested in an increase in its temperature in part or all of the permafrost profile, are discussed. However, special attention is paid to the degradation characteristics from the permafrost base. In the case of moderately thick and warm permafrost in the zone of its sporadic and discontinuous occurrence, this type of degradation may particularly contribute to its disappearance, and surficial consequences of such degradation may be more serious than we expect on the basis of available research and data now. A special case of such degradation is the permafrost located in the coastal zone in the vicinity of the Hornsund Spitsbergen, where a multidirectional thermal impact is noted, also causing similar degradation of permafrost: from the top, side and bottom. Especially the degradation of permafrost from the permafrost base upwards is an entirely new issue in considering the evolution of permafrost due to climate change. Due to the difficulties in its detection, this process may contribute to the threats that are difficult to estimate in the areas of discontinuous and sporadic permafrost.
Climate warming causes the degradation of all components of the cryosphere that are more or less persistent at the Earth’s surface. The permafrost is undoubtedly one of the most stable and the most influencing component of the range of the earth’s cryosphere (Lunardini 1995). Its degradation is the subject of attention of many authors in terms of the entire Arctic (e.g., Liljedahl et al., 2016; Shi et al., 2019), within its regional aspects: Alaska (Jorgenson et al., 2001), as a part of the Russian Arctic (Vasiliev et al., 2020), or Tibet (Yang et al., 2010; Yin et al., 2021) and many diverse environments. Predominantly permafrost degradation is described most commonly as process operating from the ground surface downwards (Lawrence and Slater 2005; Delisle 2007; Frey and McClelland 2009; Streletskiy et al., 2015; Oliva et al., 2018; Luo et al., 2018; Luo et al., 2020). It includes the impact on infrastructure (Hjort et al., 2018), where the climatic influence is the most spectacular and often directly visible because the time lag between initial degradation and its further effects is not long. Hence, at the interface between the active layer (AL) and permafrost, the reaction to climate and surface warming will be the strongest and fastest, the most spectacular and at the same time the easiest to identify and measure.
The heat flux into the ground does not stop, however, at the interface between permafrost and the AL, but with a certain delay, penetrating further down. This process depends on various factors, especially heat capacity, heat permeability and amount of ice in the medium. The more complex the geological medium is, the more complicated process rel