Geoscience Reference
In-Depth Information
2007a
). The response of the international community to climate change, largely, is
wrestling with the question of how to reduce greenhouse gas emissions and slow the
long-term warming trend. The measures being discussed will be implemented over
the next decades and their impact will be felt by future generations. However, glacier
retreat caused by climatic change is currently happening worldwide and is affect-
ing water supply and triggering devastating natural hazards such as outburst floods,
rockfalls, or avalanches (IPCC
2007b
). A disconnect exists between the foreseeable
future and the present situation where unsustainable practices as well as outdated
ideas and methods continue to be practiced. Mitigation planning and capacity build-
ing adaptation to address these unavoidable and present hazards are still in their
infancy.
The Andes are the only mountain system in the Southern hemisphere with a
north-south axis that covers equatorial, tropical, subtropical, temperate, humid,
and sub-arctic climates. Due to the importance of glaciers as indicators of climate
change, Andean glaciers could provide meaningful observations over a wide-range
of environmental and climatic conditions. Gaps remain as to the evolution of
Andean glaciers, their associated impact on future water supply, and potential haz-
ards (Casassa et al.
2007
). Chile, which contains 75% of the total glacier area of
South America, has mapped 1934 glaciers covering an area 15,488 km
2
, but there
remain 4700 km
2
to be inventoried because of: (1) the vastness of the system; (2)
the remoteness and inaccessibility of some areas (especially in Patagonia and Tierra
del Fuego); and (3) the economic limitations that exist.
Although South America contains the second largest reservoir of fresh water, its
population is vulnerable to water scarcity (The World Bank
2004
). Watersheds in
the region are dependent on snowfall and glacial melt from the high mountain sys-
tem. Glaciers release water during the dry-season, a guarantee for year-round water
flow for cities, agricultural production, and industry that may not be available in the
near future (The World Bank
2004
,
2009
). Quito, Ecuador; Lima, Peru; La Paz/El
Alto, Bolivia; Santiago, Chile; and Mendoza, Argentina are inhabited by millions of
people that depend on Andean watersheds for potable water, agriculture, and hydro-
electric power generation. Glaciers in the South American high Andean systems are
currently receding at alarming rates (Rivera et al.
2002
; Casassa et al.
2007
;Bown
et al.
2008
). The glaciers in the tropical Andes (from Venezuela to Bolivia) have lost
15% of their surface area in a period of 30 years (The World Bank
2009
). In some
cases, glaciers are completely vanishing. In Bolivia, the Chacaltaya glacier has lost
95% of its surface area, while the Ecuadorian glacier, Cotacachi, has disappeared
(The World Bank
2009
). Andean cities will have to adapt to the challenge of water
scarcity while maintaining their ability to sustain urban economies.
Despite future water scarcity, increased glacial melt over the short-term has
resulted greater runoff, which has increased the risk of natural disasters such as
floods. In the Himalayas, Richardson and Reynolds (
2000
) have noted that flooding
caused by moraine-dammed lake outbursts have become more prevalent. In Latin
America, the risk of glacial lake outburst floods has also increased, especially in the
tropical Andes, where human settlements in mountainous areas are more common
(Carey
2005
;Mark
2008
). The frequency and severity of glacial lake outburst floods
and avalanches should increase with future warming in mountainous environments
