The Andean Glacier and Water Atlas

Chile and Argentina Temperatures in the mountains of Chile and Argentina have risen by about 0.2 to 0.3˚C per decade since 1976 (Falvey and Garreaud, 2009), and are still increasing (Vuille et al., 2015). Glaciers in the region, like those in the Tropical Andes, have been retreating, especially in the last decades. Large tidewater and freshwater glaciers in Patagonia and Tierra del Fuego have experienced rapid retreat (Warren and Sugden, 1993). Dramatic examples include the retreat of Jorge Montt Glacier (19.5 km between 1898 and 2011; Rivera et al., 2012a) the O’Higgins Glacier (14.6 km between 1896 and 1995; Casassa et al., 1997) the Upsala Glacier (6.7 km between 1945 and 1995; Aniya, 1995; Skvarca et al., 2003; Sakakibara et al., 2013) and the Marinelli Glacier (10.7 km between 1913 and 2000; Porter and Santana, 2003). Glacier thinning is not only restricted to low-lying areas, where it attains maximum values, but also occurs in higher elevation areas (Willis et al., 2012a, b). Due to local ice dynamics there are some glaciers which are still advancing, e.g. Pio XI and Trinidad glaciers (Casassa et al., 2014; Rivera et al., 2012). Future predictions It is predicted that glaciers over the whole of the Andes will continue to retreat. The consequent changes in hydrology will have significant impacts on communities and ecosystems. Future glacier shrinkage will lead to a long-term reduction in dry season river discharge from glacierized catchments (Vuille et al., 2018).

Permafrost and Rock Glaciers Permafrost, or frozen ground, forms at high altitudes and, like glaciers, is sensitive to temperature changes. Warming, glacier retreat and permafrost thawing destabilise mountain slopes. The extent of permafrost in the Andes has not been extensively studied, which makes it difficult to predict the implications of thawing on communities and the environment. Active rock glaciers indicate the presence of permafrost and are the visual expression of permafrost creep (Barsch, 1996). The structure of rock glaciers makes them more resilient to warming than glaciers and as the climate warms they are expected to be an increasingly important contributor to river and stream flow. Rock glaciers are actually more abundant than glaciers in the central part of the Andes (Jones et al., 2018). However, Rangecroft et al. (2016) looked at the current extent and future projections for the fate of permafrost and active rock glaciers in the Bolivian Andes. They found the projected warming would result in the loss of 95 per cent of the current permafrost in Bolivia by 2050 and 99 per cent by 2099 (Rangecroft et al., 2016). These predictions include the loss of almost all of the Bolivian rock glaciers by 2099, resulting in a significant impact on water security in the country.

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