Methodology for forecasting the values of seasonal thaw layer in permafrost areas considering their degradation under climate warming

Introduction. The ongoing climate changes in the permafrost zone associated with global warming significantly impact the temperature regime and the depth of seasonal thawing of permafrost soils. In current design practices, a constant calculated value for the depth of seasonal thawing is adopted; however, in reality, it varies and may exceed the design values. Existing regulatory requirements for design neglect this variation, which underscores the relevance of the study. Aim. To develop a methodology for forecasting changes in the thickness of the seasonal thaw layer based on climate parameters altering with warming. Materials and methods. The methodology of the study involved an analysis of contemporary scientific and technical literature, regulatory documents, methodological literature, and archival data from meteorological stations across Russia; determination of the relationship between changes in the depth of seasonal thawing over time; development of a forecasting methodology for changes in the thickness of the seasonal thaw layer based on climate parameters affected by warming; recommendations for utilizing the results in the development of regulatory and technical documents. Results. The depth of seasonal thawing significantly affects the cost and scope of foundation construction and land planning works. The existing calculation methodology fails to account for climate change trends. The permafrost zone of Russia displays an increase in the temperature of soils and the depth of seasonal thawing. The highest convergence of calculated results with field observations was achieved using the Borey 3D heat engineering program while considering climate change. Conclusions. The depth of thawing is to be determined using a heat engineering program that accounts for climate change. Determination of the foundation bottom depth, as well as strength and deformation calculations, are to consider changes in thaw depth during operation and the impact of global warming.