Patterns of spatio-temporal paraglacial response in the Antarctic Peninsula region and associated ecological implications

The Antarctic Peninsula (AP) constitutes the warmest region of Antarctica, although 98% of the surface is still covered by glaciers. The region shows contrasting geographic and climatic properties, which have conditioned past and present glacial activity. This paper constitutes a review of the spatial and temporal patterns of paraglacial activity across the AP bridging the geomorphological and ecological perspectives. The number and extent of ice-free environments has increased since the Last Glacial Maximum, particularly during the Early Holocene and the 20th century. Following deglaciation, the redefinition of coastlines and the uplift of landmasses proceeded differently in the three sectors of AP, with maximum uplift in the western sector (40 m a.s.l.), the minimum on the north (20.4 m a.s.l.), and intermediate in the eastern sector (30 m). There are also differences in the levels of raised beaches, with the highest complexity in the northern AP (5–7 levels) and the lowest in the eastern AP (3 levels). The transition from glacial to periglacial conditions (paraglacial stage) also differed greatly between the three sectors, with the absence of rock glaciers in the western sector, the development almost exclusively of glacier-derived rock glaciers in the eastern AP, and the majority of talus-derived rock glaciers in the northern AP. The development of protalus lobes, block streams and other periglacial features was highly dependent on the cold/warm based character of individual glaciers; this characteristic determines the existence or absence of permafrost following deglaciation which, in turn, conditions the type and intensity of geomorphic processes in newly exposed ice-free areas. More recently, following the post-1950s regional warming, there have still been important differences between the three sectors in the development of paraglacial environments. Permafrost degradation has occurred in newly exposed areas, accelerating mass wasting and sediment redistribution and changing hydrological processes, especially in the northern and western AP, while sudden glacial outburst flooding has occurred in the eastern AP. The most apparent major ecological response to this recent warming is greening due to vegetation expansion, which is more evident where paraglacial and periglacial processes are less intense. The accurate characterization of the different paraglacial responses existing in the AP enables a better understanding of future environmental responses in this climatically sensitive region, where climate models forecast significant environmental change for during forthcoming decades.