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Reasons for restricted and nonuniform glaciation over High-Mountain Asia (HMA) during the global last glacial maximum (LGM; similar to 28-23 ka) have been intensively studied but remain elusive. Using a 1-km-resolution ice sheet model, we show that glaciers across HMA exhibit high region variability in glaciation. Glaciers in western and southern HMA are the most sensitive to climate change and those in the interior are the least sensitive. Our model broadly reproduces the restricted glaciation across HMA during the LGM, although it overestimates the extent of glaciation over western and southern HMA as compared with reconstructions. Modeled decreases in precipitation hampers glacier growth over northern HMA, while insufficient cooling hampers glacier advance over eastern HMA for the LGM. Both reduced precipitation and insufficient cooling inhibit large-scale glaciation over inner HMA. Moreover, climatic conditions conducive to glaciation across the entire HMA include a reduction in temperature of similar to 10 degrees C and an increase in precipitation, unlikely to have occurred during any Quaternary glacial maximum.

Plain Language Summary Presently, High-Mountain Asia (HMA) is home to the largest mass of glaciers outside the polar regions and known as the Earth's Third Pole. During the global last glacial maximum (LGM; similar to 28-23ka), geological evidence points to restricted and nonuniform glaciation over HMA, in stark contrast to the expanded ice sheets across high latitudes of Northern Hemisphere. However, it remains elusive why was there no large-scale ice sheet over HMA during the LGM. Using a 1-km-resolution ice sheet model, we highlight the climate sensitivity of glaciers across HMA showing highly region variability in glaciation and revealing that insufficient cooling and/or precipitation decrease constrained glaciation over HMA during the LGM.