Fig. 3: Relative contributions of climate and environmental factors to permafrost characteristics and changes.
a Relative importance of climate variables in explaining the temporal variation of active layer thickness (ALT) and permafrost temperatures. b Contributions of environmental factors to spatial variation in permafrost characteristics and changes. Relative importance was assessed using the Lindeman–Merenda–Gold (LMG) method (see Methods), based on climate data from 2001 to 2018, including air temperature, precipitation, wind speed, solar radiation, surface pressure, specific humidity, and freezing level height. Prior to the LMG analysis, correlation coefficients and significance levels between climate variables and permafrost characteristics were calculated using multiple region analysis to examine the impact of climate change on permafrost characteristics (p < 0.05). Variation partitioning analysis (VPA) was applied to partition variances of permafrost characteristics—active layer thickness (ALT), temperature at the top of permafrost (TTOP), and permafrost temperatures at 10 m (PT10m) and 15 m (PT15m) depths—and their change rates among temperature factors (air temperature and land surface temperature), non-temperature factors, and permafrost state variables.
