The Role of Winter Warming in Permafrost Change Over the Qinghai-Tibet Plateau

Winter warming is fast than summer warming on the Qinghai-Tibet Plateau (QTP). However, no assessment of winter warming effects on permafrost has been attempted. Here we conducted hypothetical control experiments and used the Noah land surface model to evaluate the impacts of winter warming on the QTP permafrost. The results show that air temperature in winter (November-April) was increasing at a rate of 0.66 degrees C/decade during 1980s-2000s, over double that in summer (May-October). The mean annual ground temperature of permafrost increased by 0.13 degrees C/decade. The summer warming dominated the variations in thermal regime of permafrost before 2000. After that, the influence of winter warming on permafrost thermal regime has gradually grown and exceeded that of summer warming. Winter warming has amplified the thermal degradation of permafrost. Our findings reveal that alpine continuous permafrost on the northern QTP has experienced a prominent regional warming due to rapid winter warming since 2000.