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Different aridity indices have been used to define drylands. Most of them are
based on precipitation and temperature. In 1977 the United Nations Environment
Programme (UNEP) adopted an aridity index (AI) based on the ratio between average annual precipitation and potential evapotranspiration (UNEP Index). This definition conceptualizes drylands as lands with an AI of less than 0.65. Using this
index, drylands are further divided into hyper-arid lands, arid lands, semi-arid lands,
and dry-subhumid lands. AI was used to prepare the Map of World Distribution of
Arid Regions (UNESCO 1979) and the Map of Drylands by the UN Environment
World Conservation Monitoring Centre based on the UNEP Index produced in 1991
(UNEP-WCMC 2007). Penman’s formula which is based on solar radiation, atmospheric humidity, and wind was used to estimate potential evapotranspiration. In
addition to global efforts to define arid regions, several region-specific climate classifications that include arid categories have been devised. For example, in Mexico
the Koppen Classification modified by García (2004) is commonly used.
Environmental Governance, National Policies, and Land
Property Regimes
Environmental governance has become an important analytical category for understanding the institutional and planning systems through which natural resources are
accessed and managed in Latin America. According to Paavola (2007) environmental governance is best understood as the establishment, reaffirmation, or change of
institutions to resolve conflicts over environmental resources. Although influenced
by international agreements and pressures, national state governments are ultimately responsible and sovereign in the adoption and implementation of the array
of policies available for the use and conservation of natural resources, as well as the
measures to prevent, mitigate, and adapt to environmental change and natural disasters. It is true that many countries in Latin America are large enough to host multiple
environmental contexts (e.g., ecoregions). It is also true that many countries in the
region hold forms of government that allow for differing degrees of regional independence (e.g., Mexico or Brazil). Both of these realities could and do sometimes
result in differentiated institutional arrangements of environmental governance
within the boundaries of each country.
However, the power held by central governments in establishing environmental
and land policy, as well as in empowering or weakening related institutions and
norms, is consistently superior to those at regional scales, and arguably, this power
is rarely contested. This is why we believe that for a continent-wide comparative
exploration of aridity trends and patterns, a country boundary is a reasonable unit of
analysis (Assies 2008).
Beyond subnational governments (states or regions), within country differentiation of environmental governance institutions and their potential associated outcomes can be analyzed through sectoral lenses. Existing forms of environmental
16 Drylands, Aridification, and Land Governance in Latin America: A Regional…
Different aridity indices have been used to define drylands. Most of them are
based on precipitation and temperature. In 1977 the United Nations Environment
Programme (UNEP) adopted an aridity index (AI) based on the ratio between average annual precipitation and potential evapotranspiration (UNEP Index). This definition conceptualizes drylands as lands with an AI of less than 0.65. Using this
index, drylands are further divided into hyper-arid lands, arid lands, semi-arid lands,
and dry-subhumid lands. AI was used to prepare the Map of World Distribution of
Arid Regions (UNESCO 1979) and the Map of Drylands by the UN Environment
World Conservation Monitoring Centre based on the UNEP Index produced in 1991
(UNEP-WCMC 2007). Penman’s formula which is based on solar radiation, atmospheric humidity, and wind was used to estimate potential evapotranspiration. In
addition to global efforts to define arid regions, several region-specific climate classifications that include arid categories have been devised. For example, in Mexico
the Koppen Classification modified by García (2004) is commonly used.
Environmental Governance, National Policies, and Land
Property Regimes
Environmental governance has become an important analytical category for understanding the institutional and planning systems through which natural resources are
accessed and managed in Latin America. According to Paavola (2007) environmental governance is best understood as the establishment, reaffirmation, or change of
institutions to resolve conflicts over environmental resources. Although influenced
by international agreements and pressures, national state governments are ultimately responsible and sovereign in the adoption and implementation of the array
of policies available for the use and conservation of natural resources, as well as the
measures to prevent, mitigate, and adapt to environmental change and natural disasters. It is true that many countries in Latin America are large enough to host multiple
environmental contexts (e.g., ecoregions). It is also true that many countries in the
region hold forms of government that allow for differing degrees of regional independence (e.g., Mexico or Brazil). Both of these realities could and do sometimes
result in differentiated institutional arrangements of environmental governance
within the boundaries of each country.
However, the power held by central governments in establishing environmental
and land policy, as well as in empowering or weakening related institutions and
norms, is consistently superior to those at regional scales, and arguably, this power
is rarely contested. This is why we believe that for a continent-wide comparative
exploration of aridity trends and patterns, a country boundary is a reasonable unit of
analysis (Assies 2008).
Beyond subnational governments (states or regions), within country differentiation of environmental governance institutions and their potential associated outcomes can be analyzed through sectoral lenses. Existing forms of environmental
16 Drylands, Aridification, and Land Governance in Latin America: A Regional…