Fundamental shift of ice temperature in the Third Pole under global warming

The Tibetan Plateau and its surroundings, sometimes referred to as High Mountain Asia or the Third Pole, have the largest mid-latitude glaciers and act as Asia's water tower. Previous studies based on remote sensing and ground-based measurements have revealed the magnitude and the accelerated trend of surface ice loss in this region over the past two decades. However, little is known about the englacial temperature and its response to climate change. Here we present a compilation of ice temperature profiles from 21 deep cores drilled in the accumulation zone of different glaciers covering the Third Pole. By combining these ice-core records with other climate datasets and thermal modelling, we have found that the thermal statues in the extreme high-altitude regions have undergone fundamental changes against the background of climate warming, particularly in the surrounding of Third Pole. The spatial pattern of the ice temperature structure shows clear contrasting patterns. Due to the intense latent heat generated by the refreezing of surface meltwater, the englacial temperature of boreholes in the vicinity of the Third Pole is far from a steady state, reflecting an increasing atmospheric temperature over the past decades and non-stationary climatic conditions. The repeated measurements in the same boreholes on different glaciers also showed that the englacial temperature profile can either increase or decrease, mainly depending on the effects of meltwater production and firn thickness. Such a dramatic shift in ice temperature in the Antarctic region have profound implications for glacier response to climate change and glacier-related disasters in this high-altitude regime.