Outlook on climate change adaptation in the Tropical Andes mountains

Glaciers play an important role in the hydrology of the Andes by storing water in the rainy seasons and releasing it throughout the year. The proportion of glacial meltwater in rivers is substantially higher in the dry season and in dry years (Buytaert et al., forthcoming). This is due to the lack of rain and not because of increased melting in the dry season. Glaciers have a particularly significant effect downstream in rivers that move into arid areas towards the Pacific after leaving the mountains. One extreme example is the Santa River in Peru, which receives water from glaciers on the Cordillera Blanca. On average, the contribution of glacial water in this river is between 4 and 8 per cent (Ibid.). However, in years with little precipitation the contribution can be as high as 80 per cent in the dry season. The compensation effect of glaciers is particularly important in Bolivia and Peru, where most tropical glaciers are located: here, there is the highest difference in seasonal precipitation and annual precipitation totals are low. In the short term in the Tropical Andes, diminishing glaciers cause increased water flow, but in the long term there will be reduced dry season compensation (Vuille 2013), which is mainly important for local ecosystems and mountain communities. High mountain grass- and wetlands Grass- and wetlands cover the areas of the high Andes from the treeline and up to the edge of the snow. These unique ecosystems include the neotropical alpine grasslands, known as páramos, dry and wet puna grasslands and other wetlands. Páramos cover the upper part of the northern Tropical Andes and wet punas occupy a similar niche in the Central Andes. These grasslands, containing millions of streams, rivers, lakes, and various kinds of wetlands, are crucial to the hydrology of the mountains, providing water to tens of millions of

people downstream. They are also important for biodiversity and provide carbon storage (Myers et al., 2000). Carbon stocks in Andean ecosystems are comparable with those in tropical lowland forests, especially when organic carbon stocks in the soil are considered (Spracklen and Righelato, 2014). Anthropogenic pressure, from agriculture and

climate change in particular, threatens the capacity of these ecosystems and their services. Páramos are among the ecosystems most threatened by climate change, with one biome-based model predicting a loss of 31 per cent of páramos by 2050 (Tovar et al., 2013), without including the added threat of land- use change.

Deforestation in the Tropical Andes region

VENEZUELA

Other forest cover Intact forest landscape* Net forest loss (2000-2014) Forest and forest loss areas Annual deforestation rate

COLOMBIA

Percentage

0,4

2001-2005

ECUADOR

BRAZIL

2006-2010

0,2

0

Forest and forest loss extent Thousands square kilometres

PERU

800

Tropical Andes

100

BOLIVIA

PARAGUAY

1

Forest (2014)

Net forest loss (2000-2014)

*De ned as an unbroken expanse of natural ecosystems within the zone of current forest extent, showing no signs of signi cant human activity and large enough that all native biodiversity could be maintained

ARGENTINA

Source: based on Hansen/UMD/Google/USGS/NASA, 2013

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