The Karakoram Anomaly? Glacier Expansion and the ‘Elevation Effect,’ Karakoram Himalaya

TLDR

In the late 1990s, glaciers in the central Karakoram expanded—a stark contrast to global retreat—primarily in the highest basins, growing rapidly with frequent surges, yet no long‑term climatic or glaciological monitoring exists at those elevations. This article investigates explanations for the anomalous expansion by integrating short‑term monitoring, low‑altitude weather stations, and the region’s unique environmental characteristics. The authors attribute the expansion to interactions among regional air‑mass climatology, verticality effects on glaciers, debris sensitivity, complex temperature distributions, and thermal shifts that accelerate ice redistribution by elevation. Valley stations show rising precipitation and modest summer cooling over 50 years, hinting at positive mass balance, but the abrupt, high‑elevation‑only expansions remain unexplained.

Abstract

In the late 1990s widespread evidence of glacier expansion was found in the central Karakoram, in contrast to a worldwide decline of mountain glaciers. The expansions were almost exclusively in glacier basins from the highest parts of the range and developed quickly after decades of decline. Exceptional numbers of glacier surges were also reported. Unfortunately, there has been no on-going measurement of climatic or glaciological variables at these elevations. The present article examines possible explanations for this seemingly anomalous behavior, using evidence from short-term monitoring programs, low-altitude weather stations, and the distinctive environmental characteristics of the region. The latter involve interactions between regional air mass climatology, its seasonality, topoclimate or ‘verticality’ effects on glaciers with extreme altitudinal range, climatic sensitivities of heavy versus thin supraglacial debris, and complex temperature distributions in ice masses with ice falls throughout critical elevations. Valley climate stations indicate increases in precipitation over the past 50 years and small declines in summer temperatures, which may indicate positive trends in glacier mass balance. However, the suddenness of the expansions is problematic, as is their confinement to glaciers from the highest watersheds while others continue to retreat. Thermal shifts in ice masses with extreme altitude ranges may be even more critical, leading to an accelerated redistribution of ice mass by elevation.