Spatio-Temporal Assessment of Glacier Changes (1990-2025) and Their Relationship with Climate Variability in the Tirich Mir Region, Hindu Kush, Pakistan

Abstract Glaciers of the Hindu Kush region in northern Pakistan are important freshwater sources, yet; their response to recent climate variability remains spatially heterogeneous. This study assessed spatio-temporal changes between years 1990 and 2025 in five major glaciers of the Tirich Mir including massif—Dirgoi, Lower Tirich, North Barum, Owir, and South Barum—using multi-temporal Landsat imagery, the Normalized Difference Snow Index (NDSI), ASTER GDEM terrain data, and GIS-based area analysis. Landsat-5 TM, Landsat-7 ETM+, Landsat-8 OLI, and Landsat-9 OLI-2 images were analyzed for years 1990, 2000, 2010, 2020, and 2025, respectively. Climate variability was evaluated using NASA POWER summer-temperature and winter-precipitation data in R/R-Studio through linear regression, the Mann-Kendall test, Sen's slope, and Pearson correlation. Overall study findings show that total glacier extent has decreased from 64.23 km² in 1990 to 52.81 km² in 2025, corresponding to a loss of 11.42 km² (17.8%). The NDSI-derived clean-ice/snow-covered surface has declined from 36.89 km² in 1990 to 5.21 km² in 2010 and subsequently increased to 30.83 km² in 2025. Mapped debris-covered ice has increased from 27.34 km² in 1990 to 54.53 km² in 2010, while declined to 21.98 km² in 2025. Summer temperature showed a significant increasing trend (Sen's slope = 0.070°C yr⁻¹, p = 0.0071) during period of 2005–2025, whereas winter precipitation showed no significant trend. Correlations between the mapped clean-ice surface and temperature (r = -0.17, p = 0.782) and precipitation (r = 0.40, p = 0.508) were non-significant. Hence, glacier shrinkage in the Tirich Mir region occurred concurrently with significant regional warming, whereas precipitation exhibited no statistically significant trend. Overallglacier variability was found to be influenced by factors such as debris cover, topography, and seasonal snow conditions. Focusing on glaciated terrains, present study approach will be helpful in prospective studies of regional cryosphere assessment.