Monitoring changes in the dynamics of Karakoram glaciers using multi-sensor remote sensing

The glaciers of the Karakoram are among the largest reservoirs of freshwater outside of the polar ice sheets and exert a strong control over the lives of millions who live within their basins. In recent decades, anthropogenic climate change has caused widespread global glacier mass loss leading to sea level rise, shifts in water availability and in-creased risk of glacier-related natural disasters. Karakoram glaciers have long appeared to go against this global trend, displaying stable or even slightly positive mass balance, although the persistence of this trend has been highly uncertain. This thesis aims to use cutting-edge satellite-based techniques to investigate the dynamics of Karakoram glaciers and shed light on their future. First, this thesis explores the potential of submetre SAR imagery to measure fine-scale ice flow variability. Applying established feature tracking techniques to Capella SAR imagery, it is shown that these very fine resolution sensors are capable of measuring fine spatial and temporal variability, although challenges in co-registration and terrain correction may hinder broader scale applications. The second results chapter investigates an exceptional mass drainage of ponds across the surface of Baltoro Glacier that occurred in June 2022, and its relationship with ice hydrology and ice dynamics. Drawing on a variety of data sources, it is concluded that the most likely driver was the rapid depressurization of a saturated englacial hydrological network which connected hundreds of supraglacial ponds. Finally, the archive of Sentinel-1 SAR imagery was used to create an 8-year record of ice flow variability of Karakoram glaciers with a 24-day acquisition interval, which allows the analysis of seasonal as well as long-term ice flow variability. These data show that Karakoram glaciers are beginning to decelerate, symptomatic of the negative mass balances that characterise the majority of glaciers worldwide.