Climate warming has led to the degradation of permafrost stability in the past half century over the Qinghai-Tibet Plateau

Abstract. Temperature increases cause a unique type of damage to permafrost. This damage is often expressed as the degradation of permafrost thermal stability, which is very important for engineering design, resource development, and environmental protection in cold regions. This study evaluates the degradation of permafrost stability over the QTP from the 1960s to the 2000s using estimated decadal mean annual air temperatures (MAATs) by integrating remote sensing-based estimates of mean annual land surface temperatures (MASTs), leaf area index (LAI) and fractional snow cover values, and decadal mean MAATs taken at 152 weather stations using geographically weighted regression (GWR). The results reflect a continuous rise of approximately 0.04 °C/a in the decadal mean MAAT values over the past half century. Climate warming has led to a reduction in permafrost stability in the past half century. The total degraded area of stability is approximately 153.76 x 104 km2, which corresponds to 87.98 % of the permafrost area in the 1960s. The stability of 75.24 % of the extremely stable permafrost, 89.56 % of the stable permafrost, 90.3 % of the sub-stable permafrost, 92.31 % of the transitional permafrost, and 32.8 % of the unstable permafrost has been reduced to lower levels of stability. Approximately 49.4 % of the unstable permafrost and 95.95 % of the extremely unstable permafrost has degraded to seasonally frozen ground. The sensitivity of the permafrost to climate is dependent on its stability level. The mean elevations of the extremely stable, stable, sub-stable, transitional, unstable, and extremely unstable permafrost areas increased by 88 m, 97 m, 155 m, 185 m, 161 m and 250 m, respectively. The degradation mainly occurred from the 1960s to the 1970s and from the 1990s to the 2000s. This degradation has led to increases in risks to infrastructure, increased flood risks, reductions in ecosystem resilience, and positive climate feedback effects. It therefore affects the well-being of millions of people and sustainable development at the Third Pole.