Climatic Change (2007) 83:9–38 DOI 10.1007/s10584-006-9125-3 Archival explorations of climate variability and social vulnerability in colonial Mexico Georgina H. Endfield Received: 27 September 2005 / Accepted: 3 April 2006 / Published online: 8 March 2007 C Springer Science + Business Media B.V. 2007 Abstract In this paper, unpublished archival documentary sources are used to explore the vulnerability to–and implications of–climatic variability and extreme weather events in colo- nial Mexico. Attention focuses on three regions covering a variety of environmental, social, economic, and political contexts and histories and located at key points along a north-south rainfall gradient: Chihuahua in the arid north, Oaxaca in the wetter south and Guanajuato located in the central Mexican highlands. A number of themes are considered. First, the significance of successive, prolonged, or combined climate events as triggers of agrarian crisis. Second, a case study demonstrating the national and regional impacts of a particu- larly devastating climate induced famine, culminating with the so-called ‘Year of Hunger’ between 1785 and 1786, is presented. The way in which social networks and community engagement were rallied as a means of fortifying social resilience to this and other crises will be highlighted. Third, the impacts of selected historical flood events are explored in order to highlight how the degree of impact of a flood was a function of public expectation, preparedness and also the particular socio-economic and environmental context in which the event took place. An overview of the spatial and temporal variations in vulnerability and resilience to climatic variability and extreme weather events in colonial Mexico is then provided, considering those recorded events that could potentially relate to broader scale, possibly global, climate changes. 1 Introduction There is little doubt that climate change poses one of the greatest threats to humankind world- wide. The precise impacts of predicted changes for different social, economic and ecological systems are less clear (Schneider 2001). Vulnerability is greater among the environmentally, politically, socially or economically marginal groups, whose ability to adapt to and recover from environmental changes and biophysical events can be limited or constrained (Cutter G. H. Endfield School of Geography, University of Nottingham, University Park, Nottingham, NG 7 2RD, UK e-mail: georgina.endfi[email protected] Springer 10 Climatic Change (2007) 83:9–38 1996; Ribot et al. 1996; Liverman 1999; Adger et al. 2001; Fraser et al. 2003). For these reasons, it is anticipated that the impacts of future climate changes are likely to be felt most severely by resource dependent societies in the developing world (Liverman 1999). Much more information, however, is needed on the relative vulnerability of different regions, na- tions and socio-economic groups, to climate changes at a range of scales (Parry 2001: 258). Indeed, the assessment of differential spatial and social vulnerability to predicted climate changes has been identified as a priority research area (Adger and Kelly 1999). Investigating such themes poses a number of challenges (Patt et al. 2005). Vulner- ability is a composite and multidimensional concept that can be discussed in environ- mental and ecological terms, in relation to political economy or as a reflection of social relations and class structure. As a result, there are many definitions of- and approaches to climate change vulnerability (Luers et al. 2003: 255). As Kelly and Adger (2000: 326) have suggested, however, any analysis of human vulnerability to climate change should consider the social, economic and institutional factors that influence differential social vulnerability among societies and that thus promote or constrain opportunities for adaptation. To date, most investigations of climate change vulnerability and adaptive capacity have been based on current and predicted climate change scenarios. As Maga˜na et al. (1997) have demonstrated, comparisons between current situations and conditions and those that could prevail with predicted climate changes in the future can provide an indication of the most vulnerable regions. Research has also focused on the development of vulnerability indices to identify those societies most at risk from predicted climate changes (Parry 2001; Sullivan and Meigh 2005; Brooks et al. 2005). Deriving insights about the implications of contemporary and future climate changes from the historical record is problematic (McNeill 2005: 178). The fact that past societies differ markedly from those in the modern world makes simple analogies or parallels unrealistic (Ingram et al. 1981: 5; Meyer et al. 1998). However, knowledge of successes and failures in adaptation to past climatic variability can increase the ability to respond to the threats of long-term climate changes (Adger and Tompkins 2004). Yet there have been relatively few historically oriented assessments of vulnerability and adaptation to climate change (Cutter 1996: 533). As a result, we are only partially aware of the ways in which adaptations to climatic variability may lead to socially differential effects. There is considerable debate as to whether modern society is effectively becom- ing more or less vulnerable as a result of technological innovation and adaptation over time (see Meyer et al. 2000: 240–241). The “lessening hypothesis” suggests that societies, who adapt technologically and socially, are able to effectively reduce the degree of im- pact of recurrent climatic fluctuations of similar magnitude and can thus indirectly lessen the impacts on the entire society. However, according to the “catastrophe hypothesis”, in- creasingly elaborate technical and social systems, designed to buffer against the impacts of recurrent and expected climatic fluctuations, can actually increase social vulnerability to catastrophe resulting from less frequent natural and social perturbations (Bowden et al. 1981). Time and place specific social, economic, demographic and environmental conditions are thus pivotal to shaping the vulnerability of a particular society or group of people to climate change and particular weather events, but also play a key role in determining the relative success or failure of adaptive strategies. For this reason, it is only by conducting detailed, regionally focused historical studies of social interaction with climatic variability, that changing vulnerabilities, or what Messerli et al. (2000) have referred to as “trajectories of vulnerability” and adaptation can be understood. This paper represents an archival exploration Springer Climatic Change (2007) 83:9–38 11 of vulnerability to climatic variability and extreme weather events in colonial Mexico, and provides one such historical study.1 2 Climate change and vulnerability in Mexico 2.1 Climatic characteristics and variability Mexico comprises a region of climatic variability, sensitivity and diversity. Latitudinally, the central and southern part of the country lies within the Tropics and the northern half, within the Sub-Tropical zone. As a result, there are clear climatic distinctions between northern and the central/southern Mexico. The Trade Winds deliver summer rainfall to the central and southern regions of the country when the Intertropical Convergence Zone (ITCZ) shifts northwards, and the Sub-Tropical High Pressure belt brings stable dry conditions to the country during the northern hemisphere winter when the ITCZ is displaced equator-wards. The northern part of the country tends to be marginal to the summer trade winds, though the north west of the country is affected by the Westerlies during the boreal winter, which can bring rainfall to the region (Metcalfe 1987; O’Hara and Metcalfe 1995). The latter part of the wet season (July–September) is governed by the Mexican monsoon, but there is a relatively drier period between July and August known as the sequia intraestival or mid-season drought that varies in intensity and (exact) timing from year to year. Although, the distribution and total annual rainfall across the country is largely determined by shifts in the strength and location of these dominant atmospheric circulation systems, a number of other climatic features play an influential role. These include hurricanes and tropical cyclones, which typically affect both Caribbean and Pacific coasts between May and November, with September having the greatest frequency. Mid-latitude cyclones can bring rain, hail, sleet and snow. Severe thunderstorms, which form along or ahead of cold fronts, are also common during spring and summer months and are often accompanied by hailstorms (Mosi˜no Alem´an and Garc´ıa 1974). El Ni˜no Southern Oscillation (ENSO) events are thought to be among the most significant causes of inter-annual climate variability across the country. Evidence of ENSO related rainfall anomalies based on instrumental data, for example, suggests that during warm ENSO (El Ni˜no) events, there is an enhancement of the mid-latitude westerlies, bringing above normal rainfall to northern Mexico in the normally dry season (between November and April). In contrast, a reduced flow of air across the country with the ITCZ to the south can result in drought across central Mexico. Cold (La Ni˜na) events have been linked to lower than average winter rainfall in northern Mexico and higher than average summer rainfall in central Mexico (Ropelewski and Halpert 1986, 1989; Hastenrath 1988; Cavazos and Hastenrath