Fig. 1: Change in active layer thickness (ALT) on the Tibetan Plateau.
a Mean values and change rates (Ralt) of ALT, represented by the color intensity of the bubbles. b Unbalanced group box plots of ALT and Ralt for different terrain types—mountain areas (Mt.), basin (Basin), high plains (Plain), and valleys (Valley)—as well as for vegetation types: alpine desert steppe (ASD), alpine steppe (AS), and alpine meadow (AM). Each group includes a box plot on the left and a corresponding scatterplot on the right. In the box plots, the box spans the interquartile range (IQR, 25th to 75th percentiles), the horizontal line represents the median, and whiskers extend to 1.5 times the IQR beyond the quartiles. Topographic base maps used in a and b were generated by the authors using the ALOS PALSAR digital elevation model (20 m resolution), © JAXA/METI, accessed via the NASA Alaska Satellite Facility (ASF). c Trends and rates over a 5-year running window from 2001 to 2020. Bold lines indicate observed values (means of all sites) and dashed lines are trends estimated by linear regression. Rates were estimated using a 5-year moving window approach, with the value plotted for a given year representing the trend calculated over the 5-year window centered on that year (e.g., 2003 represents the trend for 2001-2005). Shaded areas indicate 95% confidence intervals for ALT and its change rates. Asterisks denote statistical significance (***p < 0.001; **p < 0.01; *p < 0.05). d Spatial distribution of ALT and its change rate, with bubble color intensity indicating magnitude.
