## 5 Conclusions  
The atlas depicting climatic changes of basic hydrometeorological parameters in the western part of the Russian Arctic over 1950-2021 is the first experience of building a specialized climatic cartographic product for the needs of the Russian railways [77]. It contains 459 maps of mean seasonal and decadal characteristics of surface air temperature (69 maps), total precipitation (69 maps), wind speed at ground surface (69 maps), soil temperature (63 maps), soil moisture (63 maps), air humidity (63 maps), and snow cover thickness (63 maps), along with their mean rates of change (linear trends). This article details the initial data and GIS-based methodology used for compiling the atlas; and provides its main features and examples of certain map types. In addition, it discusses the most intriguing results that come from the interannual variability of the studied parameters, which are crucial for the railway operation in the northwestern part of the Russian Arctic. We show that the climate warming in the studied area is very irregular within a year (by months), spatially, and even along each section of the railway (from 0.5 \({}^{\circ}\)C to 2.6 \({}^{\circ}\)C between 1980-1999 and 2000-2021). The rate of air temperature increase is maximal exactly in the last 20 years and reaches 0.5 \({}^{\circ}\)C per 10 years. The observed climate warming led to a 2-4 cm reduction in snow cover thickness from 1980-1999 to 2000-2021 in the western and eastern parts of the studied area, i.e., by approximately 10%. As the climate is becoming warmer, soil temperatures increase significantly. Average temperature change in the upper 10 m of soil between the 1980-1999 and 2000-2021 periods varies from 0.2 \({}^{\circ}\)C to 0.8 \({}^{\circ}\)C. Between 1980-1999 and 2000-2021, there is a significant increase in precipitation, which in some months and in some areas ranges from 25% to 50% of average values. The highest rate of precipitation growth is observed precisely within the last 20 years, when it reaches 10% per 10 years along almost all railway sections. The performed analysis has revealed significant spatial and temporal heterogeneity of the considered parameters variability. These results suggest that a thorough study of the climatic parameters along each railway section separately is needed. This will make it possible to clarify the observed changes and improve the forecast for individual railway sections. The future research in this direction will result in: (1) creation of specialized diagrams (Hovmoller diagram) of spatial and temporal variability of selected hydrometeorological parameters along the main railway sections in the northwestern part of the Russian Arctic; (2) creation of maps and diagrams of spatial and temporal variability of extreme weather phenomena in the form of observed anomalies, occurrence frequency and duration; (3) creation of forecast maps of spatial and temporal variability of basic hydrometeorological parameters up to the end of the 21 st century for the existing and planned railway infrastructure. Particular strengths of this study concern a choice of the meteo-parameters, specification of the maps, visual representations of the maps (color scales, isolines, railway lines, rivers, coastlines, geographical projection, etc. ), original algorithms of geospatial data processing and their representation in the in GIS environment, and our own recommendations derived from the research on how to improve future generations of the atlas. This is why we describe in detail technical aspects of the atlas construction that can be used by our followers to avoid mistakes and save time in building atlases for other similar regions in the world. This is the first experience in building a specialized climatic cartographic product for the needs of the Russian railways, and to our knowledge the first atlas such as that in the world. The atlas expansion and improvement will be continued in the framework of the Russian Science Foundation Project No.