This paper identifies rare climate challenges in the long-term history of seven areas, three in the subpolar North Atlantic Islands and four in the arid-to-semiarid deserts of the US Southwest. For each case, the vulnerability to food shortage before the climate challenge is quantified based on eight variables encompassing both environmental and social domains. These data are used to evaluate the relationship between the "weight" of vulnerability before a climate challenge and the nature of social change and food security following a challenge. The outcome of this work is directly applicable to debates about disaster management policy.anaging disasters, especially those that are climate-induced, calls for reducing vulnerabilities as an essential step in reducing impacts (1-8). Exposure to environmental risks is but one component of potential for disasters. Social, political, and economic processes play substantial roles in determining the scale and kind of impacts of hazards (1,(8)(9)(10)(11)(12). "Disasters triggered by natural hazards are not solely influenced by the magnitude and frequency of the hazard event (wave height, drought intensity etc.), but are also rather heavily determined by the vulnerability of the affected society and its natural environment" (ref. 1, p. 2). Thus, disaster planning and relief should address vulnerabilities, rather than returning a system to its previous condition following a disaster event (6).Using archaeologically and historically documented cultural and climate series from the North Atlantic Islands and the US Southwest, we contribute strength to the increasing emphasis on vulnerability reduction in disaster management. We ask whether there are ways to think about climate uncertainties that can help people build resilience to rare, extreme, and potentially devastating climate events. More specifically, we ask whether vulnerability to food shortfall before a climate challenge predicts the scale of impact of that challenge. Our goal is both to assess current understandings of disaster management and to aid in understanding how people can build the capability to increase food security and reduce their vulnerability to climate challenges.We present analyses of cases from substantially different regions and cultural traditions that show strong relationships between levels of vulnerability to food shortage before rare climate events and the impact of those events. The patterns and details of the different contexts support the view that vulnerability cannot be ignored. These cases offer a long-term view rarely included in studies of disaster management or human and cultural well-being (for exceptions, see refs. 13 and 14). This long time frame allows us to witness changes in the context of vulnerabilities and climate challenges, responding to a call for more attention to "how human security changes through time,

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37Archaeological records provide a unique source of direct data on long-term human-38 environment interactions and samples of ecosystems affected by differing degrees of human 39 impact. Distributed long-term datasets from archaeological sites provide a significant contribution 40 to establish local, regional, and continental-scale environmental baselines and can be used to 41 understand the implications of human decision-making and its impacts on the environment and the 42 resources it provides for human use. Deeper temporal environmental baselines are essential for 43 resource and environmental managers to restore biodiversity and build resilience in depleted 44 ecosystems. Human actions are likely to have impacts that reorganize ecosystem structures by 45 reducing diversity through processes such as niche construction. This makes data from 46 archaeological sites key assets for the management of contemporary and future climate change 47 scenarios because they combine information about human behavior, environmental baselines, and 48 biological systems. Sites of this kind collectively form Distributed Long-term Observing Networks 49 of the Past (DONOP), allowing human behavior and environmental impacts to be assessed over 50 space and time. Behavioral perspectives are gained from direct evidence of human actions in 51 response to environmental opportunities and change. Baseline perspectives are gained from data 52 on species, landforms, and ecology over timescales that long predate our typically recent datasets 53 that only record systems already disturbed by people. And biological perspectives can provide 54 essential data for modern managers wanting to understand and utilize past diversity (i.e., trophic 55 and/or genetic) as a way of revealing, and potentially correcting, weaknesses in our contemporary 56 wild and domestic animal populations. 57 58