Numerical modelling of historical front variations and the 21st-century evolution of glacier AX010, Nepal Himalaya

Due to the lack of measurements of ice velocity, mass balance, glacier geometry and other baseline data, model-based studies of glacial systems in the Nepal Himalaya are very limited. Here a numerical ice-flow model has been developed for glacier AX010 in order to study its relation to local climate and investigate the possible causes of its general retreat since the end of the Little Ice Age. First, an attempt is made to simulate the historical front variations, considering each climatic parameter separately. Good agreement between the observations and model projections can be obtained under the assumption that variations in glacier front position are a response to changes in temperature alone. The same assumption is made about future changes to explore the 21st-century evolution of the glacier. Under a no-change scenario, the glacier will retreat by another similar to 600m by AD 2100, whereas it is projected to vanish completely during this century for all trends with a temperature rise larger than +2.5 degrees C by AD 2100 with respect to the 1980-99 mean. With constant precipitation at the 1980-99 mean, the model predicts that the glacier will cease to exist at AD 2083, 2056 or 2049 if the temperature rises linearly by 3 degrees C, 4.5 degrees C or 6 degrees C respectively by the end of this century. With an additional range of precipitation changes between -30% and +30%, the life expectancy of glacier AX010 varies by 18, 6 and 2 years for the respective temperature rises. Thus the role of precipitation becomes minimal for the higher trends of temperature rise.