HAIL · High Asian Icy Landscapes during warm interstadials (HAIL): coupling between monsoon intensity and past glacier culminations?

High Asian Icy Landscapes during warm interstadials (HAIL): coupling between monsoon intensity and past glacier culminations?

Mountain glaciers are among the most sensitive indicators of climate change. They typically respond to changes in climate by expanding when the climate cools (less melt) or retreating when the climate warms (more melt). Understanding glacier change beyond the historical record has great societal relevance because it allows us to untangle how glaciers respond to non-human induced climate change. For example, the growth and retreat of the mid-latitude ice sheets was caused by 100 thousand year-long-cycles of orbital changes in insolation intensity, and they culminated in size about 22 thousand years ago (global Last Glacial Maximum, LGM). However, superimposed on this cycle, between 29 and 57 thousand years ago, are much more rapid millennial-scale transitions between cold and warm intervals, which could also drive glacier change. The mechanisms behind these rapid climate shifts are not fully understood but their fingerprints can be traced all the way to high-mountain Asia (HMA), which includes the Tibetan Plateau, the Himalaya, Pamir, Karakoram, Tian Shan, and Altai. Here extensive glacier culminations have been shown to broadly overlap with the period of these rapid shifts, out-of-phase with restricted mid-latitude ice sheets. A large uncertainty hindering explanation of this out-of-phase behavior includes the role of increased precipitation intensities caused by variations in the Mid-Latitude Westerlies and the Asian Monsoons. As current climate change is rapid, understanding the spatial and temporal patterns of glacier change during past periods of rapid climate shifts becomes increasingly important. The out-of-phase behavior is also regionally complex. Not all ice sheet sectors culminated concordantly and similarly there are potentially large regional variability in the timing and extent of glacier culminations across HMA. HAIL was therefore designed to create a bridge between empirical and numerical glacier-climate reconstructions to systematically evaluate existing empirical data on past glacier change in HMA and address one of the long-standing questions in the fields of paleoglaciology and paleoclimatology: what made High Asian glacial systems so exceptional that they responded out of-phase with the rest of the world’s ice masses to globally warmer conditions between 29 and 57 thousand years ago? The research objectives of HAIL are to (1) produce a database of empirical paleoglacier reconstructions, which can be used to constrain and interpret glacier models; (2) combine paleoclimate proxy data with model-based simulations of empirical glacier reconstructions to evaluate climate controls on spatial and temporal glacier variability; and (3) decouple regional from global climate drivers of documented glacier culminations.

Data: CORDIS, © European Union