188.8.131.52.5. Extreme events
Cold and warm fronts, tropical cyclones, and severe convergence are some of
the most frequent phenomena that produce floods, droughts, mud and snow slides,
heat waves, frosts, and climate-related fires throughout Latin America. These
extreme events produce direct and indirect impacts on productivity and affect
the quality of life for Latin Americans. A hazard (extreme climate phenomenon)
becomes a disaster when it outstrips the ability of a country or region to cope.
There are subregions of Latin America where the occurrence of extreme events
is very frequent. Central America and southern Mexico often experience the effect
of tropical cyclones and associated heavy rain, flooding, and slides. For northwestern
South America and northeastern Brazil, many of the extremes that occur are highly
related to El Niño.
Sometimes these extreme events could be magnified to such a level (extreme
of extremes) that the impact becomes a disaster. In Latin America, interaction
with other complex phenomena, such as interannual or interdecadal oscillations,
can contribute to create the appropriate conditions to produce a disastrous
impact. Examples of these extraordinary extreme events include Hurricane Mitch
in Central America, heavy rains in Venezuela, some of the most severe droughts
in northeastern Brazil, and variations in ocean currents during El Niño
for Peru and Ecuador.
Emanuel (1987, 1991) has suggested that warmer surface conditions and colder
lower stratospheric temperatures would result in stronger hurricanes. Data for
the eastern Pacific region indicate that the number of strong hurricanes in
the region has been increasing since 1973 (Whitney and Hobgood, 1997). Such
changes may represent a major environmental threat for countries such as Mexico
(Jáuregui, 1995) and the Central American isthmus.
Some of the relatively weak cold surges may exhibit unusual intensity, causing
frosts and low temperatures in coffee-growing areas of southeastern Brazil,
resulting in heavy damage and losses in coffee production (Marengo et al.,
1997). In the Mexican Altiplano, dry atmospheric conditions result in radiative
cooling and frosts even during the summer (Morales and Magaña, 1998).
Even though it is still uncertain how global warming may affect the frequency
and intensity of extreme events, extraordinary combinations of hydrological
and climatic conditions historically have produced disasters in Latin America.
Thus, in assessing vulnerability and adaptation mechanisms, it is necessary
to consider the potential influence that global warming might have on extreme