Ancient Montezuma baldcypress (Taxodium mucronatum) trees found in Barranca de Amealco, Queretaro, have been used to develop a 1,238‐year tree‐ring chronology that is correlated with precipitation, temperature, drought indices, and crop yields in central Mexico. This chronology has been used to reconstruct the spring‐early summer soil moisture balance over the heartland of the Mesoamerican cultural province, and is the first exactly dated, annually resolved paleoclimatic record for Mesoamerica spanning the Late Classic, Post Classic, Colonial, and modern eras. The reconstruction indicates that the Terminal Classic drought extended into central Mexico, supporting other sedimentary and speleothem evidence for this early 10th century drought in Mesoamerica. The reconstruction also documents severe and sustained drought during the decline of the Toltec state (1149–1167) and during the Spanish conquest of the Aztec state (1514–1539), providing a new precisely dated climate framework for Mesoamerican cultural change.

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En el suroeste del estado de Chihuahua, México, en la reserva “Cerro El Mohinora” se desarrollaron series de tiempo dendrocronológicas de madera temprana, tardía y anillo total de Pseudotsuga menziesii con una longitud de tres siglos y medio (1657-2005), con el objetivo de analizar la variabilidad hidroclimática histórica de la región. La reconstrucción de precipitación invierno-primavera indica gran variabilidad interanual, decenal y multidecenal de los patrones de precipitación para la región. Sequías severas se reconstruyeron para los periodos 1695-1715, 1753-1760, 1785-1792, 1798-1806, 1819-1830, 1841-1870, 1890-1897, 1906-1912, 1924-1941, 1971-1977 y 1994-2005, aunque las sequías más prolongadas ocurrieron en los periodos 1695-1715, 1841-1870 y 1924-1941. Las últimas tres décadas del siglo XX y los años corrientes de la primera década del siglo XXI (1971-2005) indican un periodo de intensa sequía para la región, con impactos en lo ecológico y socioeconómico aun no cuantificados.

Natural disasters related to hydro‐meteorological events have increased during the last few decades, both in frequency and severity. Mexico is heavily exposed to climate change, but has also suffered in the past from climate variability (Blümel, 2009). The new risks oblige the government to develop mitigation processes, while the affected people are implementing strategies of adaptation and resilience‐building, mostly at the family and community level. This includes forced migration due to climate change into the slums of megacities or illegal immigration to the United States. The arid, semi‐arid and subhumid condition of 49.2 per cent of the territory of Mexico is seriously affected by climate change. In addition, poverty and the lack of jobs have created complex livelihood situations, in which young people leave rural areas, partly due to socio‐economic pull factors. In this paper, we address the functional relationships between climate patterns and migration processes in Mexico, highlighting the linkages between the origin of migrants, their economic activity and their vulnerability to extreme events and we discuss long‐term climate patterns. Agriculture still uses 78 per cent of the available water in Mexico. In the drylands the competition for water use requires an integrated policy to deal with the new threats from climate change, including mitigation from the top down and adaptation processes from the bottom up to reduce the social vulnerability of the rural population in the highly affected drylands of the central and northern parts of Mexico. The new policy for administering water resources, which promotes the efficient use of an increasingly scarce and polluted resource, still suffers from a lack of participation by the affected rural population. In this paper, we propose an integrated management system from the watershed onwards, involving socio‐economic, political, cultural and hydrological variables, to deal with the rising scarcity of water, and the uncertainty and complexity of climate change.