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unfavourable conditions for investments in agriculture. Under
highly hazardous climatic conditions, farmers prefer to work
with low inputs for agriculture, in order to reduce economic
risk. This leads to low yields and low income, and conse-
quently, social deterioration. Very often, it is the primary
cause of migrations. This phenomenon has been very marked
in northeastern Brazil, northern Argentina, Chile and
Mexico.
3
Crop yield decreases, especially in tropical climates, are
caused primarily by the increase in temperature, which short-
ens the duration of crop growth cycle. Biological phenomena
occur faster at high temperature, reducing the time of dry matter
accumulation and, consequently, the production of fruits, grains
and plant aerial organs. In arid climates of the continent (north-
eastern Brazil, northern Mexico, Peru and Chile, and southern
Argentina), this negative impact is reinforced by a decreasing
annual rainfall. In humid tropical climates (Amazon basin,
In extensive areas of the continent, the productivity of agri-
cultural lands shows a decreasing trend affecting the
livelihood of population, and ecosystems as well as natural
plant cover and biodiversity. This is the final result of a
number of causes, such as unsound agricultural practices,
ecosystem fragility, human pressure and climate change,
which is becoming more hazardous. Land degradation is the
first phase of a long chain affecting the integrity of the ecosys-
tems, ecosystem services and the capacity of the territory to
hold human activities. One example of this is the El Niño-La
Niña phenomenon. During the warm period of Pacific waters,
intensive precipitations occur in the Southern Cone (Peru,
Chile, Argentina, Pacific and Atlantic coasts), while droughts
affect Colombia, Venezuela, Mexico, northeastern Brazil and
the Amazon basin. During cold spells, antagonic effects tend
to occur. This phenomenon, apart from being a threat to
human settlements, produces floods and landslides, creating
Main changes forced by global warming in Latin America and the Caribbean
Ice bodies
Elevation of lower border of Andean glaciers, decrease in the Anctartic Ice extent, retreat of the Patagonic glaciers, reduction
of permafrost, reduction of solid precipitation and snow reserves in the Andes and high elevations.
Freshwater availability
Increased runoff in winter reducing availability of water in spring and summer. Loss of capacity of hydrological regulation of
the main river basins in the Andes Mountain based on snow reserves.
Decreasing precipitation is reducing potential for rainfed agriculture in arid environments. As consequence of this,
groundwater is being overused, increasing depth of water tables.
Water quality
Intensive storms are more frequent, causing more soil erosion and sediment transportation to rivers.
Higher temperatures tend to reduce dissolved oxygen impairing aquatic organisms.
Stalinization of river deltas due to the increase in sea level.
Climatic variability
Extreme climatic events are increasing in frequency, making life hazardous. This is affecting wildlife and agriculture.
Some ecosystems from the Atacama Desert border are in ecological regression due to the increased climatic variability which
magnifies human pressures. Drought, floods and landslides are affecting agriculture and human settlements. In some cases
causing loss of human lives.
Rangelands
Important areas of the continent support extensive cattle production, in some cases this activity represents an important
export product (Uruguay and Argentina). These agricultural ecosystems are threatened by water and wind erosion due to
increased climatic aggresivity.
Forests
The continent holds one of the bigger world forest reserves. Tropical forest is threatened by a combination of human action
and climate. Tropical forest soils in the Amazon basin are very sensitive.
Biodiversity
Global warming and changes in water regime are threatening important biodiversity of tropical rain forest (Amazon basin and
Central America), Semiarid tropical steppes (Caatinga from the NE Brazil), Cold Steppes of the Andean highlands (mainly
Peru, Bolivia, Argentina and Chile), Subdesertic and semiarid temperate Steppes in Mexico, Peru, Chile and Argentina,
Humid temperate forest (evergreen and deciduous) in Chile and Argentina and Cold Patagonian Steppes. Primary factors of
degradation of these biomes is soil desiccation and droughts, displacement of isotherms faster than species adaptation and
frequent intense storms which degrades or saturate soils. Temperature increase also creates favorable conditions for new
species of insects or diseases.
Soil carbon and organic mater
Higher temperatures favour organic matter degradation when soils are cultivated. This accelerates the loss of carbon from
cultivated soils. This is the normal situation in tropical soils, which is shifting to temperate zones.
Crop seasonality
Higher temperatures will be compensated with changes in crop seasonality. Sowing dates will move towards the coldest
season to maintain yields. In Mediterranean climates this could help in a better use of winter rains, reducing water
requirements. This paradox has already been seen during simulation models in South America.
Source: modified from Santibañez (1991), IPCC (2001) and van Dam et al. (2002), Campos, 1996