Late Pleistocene glaciers to present-day snowpatches: a review and research recommendations for the Marrakech High Atlas

Abstract

AbstractThere are no glaciers today in the High Atlas, Morocco. However, there is evidence that niche glaciers and late-lying snowpatches in the High Atlas were present as recently as the last century and there are at least four sites where snowpatches appear to survive some summer seasons today. Many other sites also support non-perennial late-lying snow below steep shaded north and northeast-facing cliffs at altitudes > 3100 m. Coarse sediment ridges interpreted as moraines or pronival ramparts enclose most of these snowpatches. These landforms most likely record the positions of former niche glaciers and late-lying snowpatches in the Little Ice Age. The niche glaciers and late-lying snowpatches survived below the regional equilibrium line altitude because of strong local topoclimatic controls. In addition to strong shading, many of the current late-lying snowpatches are fed by long deep gullies which funnel avalanching snow from the cirque backwalls. The disappearance of many perennial snowpatches in the last few decades coincides with a strong trend towards warmer summer air temperatures since the 1970s (> 2 °C). However, inter-annual changes in snowpack mass balance are affected by very large variations (> 400% variability) in winter precipitation. A new research programme is underway investigating the history of late-lying snow and cirque glaciers in the High Atlas. A particular focus of this research is to utilise geomorphological and geochronological evidence to understand fluctuations in snow and ice through the Holocene and link this to continuous records of environmental change in the High Atlas region.