USGCRP Home National Assessment Acclimations September-October 1999 Impacts of Climate Change and Climate Variability in Mexico | | Search |
By Cecilia Conde, CiudadUniversitaria, Mexico; and Carlos Gay, Instituto Nacional de Ecologia, M�xico
Within Phase I of the "Country Study: Mexico" (1994 - 1996), the vulnerability of Mexico was studied under climate change conditions considering seven research areas: Forestry, Desertification and Drought , Human Settlements, Energy and Industry, Agriculture, Hydrology and Coastal Zones. Except for the Coastal Zones study, climate change scenarios were constructed using arbitrary incremental and temperature/precipitation anomalies obtained from two General Circulation Models: CCCM and GFDL. Regional climate change scenarios were also generated for Mexico based on statistical downscaling techniques applied to GCM output from 2´ CO2 experiments. Results indicate that Mexico will experience less or normal summer precipitation and increased precipitation during winter. General results of the vulnerability studies pointed to the following regions as being the most vulnerable:
Given these results, the three Mexican regions most vulnerable to climate change are, in order of importance: Central, Northern and Tabasco Coast. In a second phase of the Mexican assessment, two states were taken as Case Studies: Tlaxcala (central region) and Sonora (northern region). For those states, vulnerability and adaptation strategies are being analyzed, considering also the historic impacts under El Niño and La Niña conditions. The Tlaxcala Case Study is being developed in the project entitled On the use of climate forecasts for agricultural activities in the State of Tlaxcala, México. The economy of this state is highly dependent on rain-fed corn production. Population growth, erosion and drought are also acute problems in this state. Producers and state managers are participating in this project. For the Sonora studies, the project entitled Climate Variability and Its Potential Impact on Transboundary Freshwater Resources in North America was developed, in cooperation with the University of Arizona. Various studies have shown that the El Niño/Southern Oscillation phenomenon mainly affects precipitation and moisture conditions over Mexico. The ENSO signal may explain up to 25% of the variability in monthly precipitation in some parts of Mexico, particularly along the northern Mexican states. The ENSO impacts are summarized in Table 1. Table 1. El Niño and La Niña impacts,
In the State of Tlaxcala, various climatic regimes are found, in relation to complex topography and major differences in land use from one place to another. On an interannual basis, the climate of Tlaxcala is essentially regulated by large- scale atmospheric circulation, such as those observed during El Niño events. This variability strongly affects maize production. During the Tlaxcala regional study, the cooperation of producers (organized in the PRODUCE A.C. Foundation) and state government officials was crucial. Through periodic discussions, climate products were delivered as useful information to plan agricultural activities and this was also a way to analyze adaptation strategies. The CERES maize model, which included information obtained from farmers, was also used to examine impacts and adaptation to drought in the Tlaxcala region. The positive experience with the use of seasonal climate forecasts in 1998 convinced producers in the state to repeat the analysis in 1999. For more information, contact Cecilia Conde, Centro de Ciencias de la Atmósfera, UNAM.Ciudad Universitaria; Circuito Exterior 04510; México, D.F. México; e-mail: conde@servidor.unam.mx; or Carlos Gay, Instituto Nacional de Ecologia, Secretaria de Medio, Ambiente Recursos Naturales y Pesca; México, D.F. México; e-mail: cgay@chajul.ine.gob.mx |
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