Morenas Coloradas rock
glacier in Argentina.
Photo: D. Trombotto
Changing permafrost conditions have already impacted ous permafrost can also exist in areas with air tempera-
and will continue to strongly impact many infrastruc- tures between –1 °C and –2 °C but much lower amounts
tures in China. Design of the Qinghai-Tibet Railway has of precipitation (300 mm per year), as in the case of the
taken into account the 2.6° C increase in air temperature Argentine Puna region. In the central Andes, perma-
predicted for the 21st century by using various cooling frost appears in groups of rock glaciers. The lower limit
techniques
88,89
. The impacts of climate changes on sta- of Andean permafrost, which on the Cordón del Plata
bility will also need to be considered in the design of the mountain range occurs at an elevation of 3700–3800 m,
proposed China-Russia Oil Pipeline. is marked by the absence of rock glaciers.
South America Features indicating permafrost degradation can be seen
d
in some rock glaciers
92
. Ground subsidence in the central

Most mountain permafrost in South America is found Andes is related to warming during the Holocene, six to
at high elevations in the Andes. The total area of South eight thousand years ago (see timeline on inside back cov-
American permafrost is estimated at 100 000 km
2
. Per- er). However, there are some signs that permafrost degra-
mafrost in the Andes varies significantly in temperature, dation has recently restarted. Since degradation of perma-
ice content, and distribution (whether it is continuous frost in rock glaciers directly affects the discharge volume
or discontinuous). Andean permafrost also varies in its of Andean rivers
93
, permafrost warming could temporarily
vulnerability to future changes in climate
90
. Continuous enhance the regional supply of fresh water. On the other
permafrost is found at various elevations, in regions hand, degrading permafrost leads to slope instability, in-
where mean annual air temperatures are –2 to –4 °C and creasing risks of hazards such as rock falls and mud flows,
mean annual precipitation is 500–900 mm
91
. Continu- which will affect Andean passes and mountain roads.
196 GLOBAL OUTLOOK FOR ICE AND SNOW