The changing face of normal disaster: risk, resilience and natural security in a changing climate.

• Author: Hultman, Nathan E.
• Position: PREVENTION, MITIGATION and PREPAREDNESS

A natural disaster is by definition remarkable, and thereby often conceived and remembered as singular and unpredictable. Since the mid-1800s, for example, only about six major tropical cyclones per decade have struck the United States, and consequently, as of 1990 just 15 percent of U.S. coastal residents from Texas to Maine had experienced a direct hit by a major hurricane. (1) Despite the perception of disaster as infrequent, a comprehensive accounting that encompasses decadal time scales and continental spatial scales underscores the regularity of disasters and extreme weather events. For example, Figure 1 on the following page depicts hurricanes and tropical storms in the United States over nearly 150 years, from 1851 to 2004, illustrating the extent to which this particular perturbation is a normal feature of the U.S. Atlantic and Gulf of Mexico coastlines.

While only about one-third of these storms were classified as major hurricanes, the overall lesson--which holds for other disasters and extreme events not depicted--is one of guaranteed hazard over spatial and temporal scales integral to infrastructure investment and effective policy formation. (2) This comprehensive perspective necessarily blurs the arbitrary boundary, derived from regularity relative to human experience, between major events and more frequent and less damaging ones. In other words, disaster preparedness requires looking beyond the probability of a singular acute hazard occurring in a particular location during a particular block of years. Indeed, smaller and less telegenic events account for a majority of human economic damage: Relatively non-dramatic droughts and floods, for example, account for over 60 percent of weather-related global economic losses. (3) Moreover, relatively ordinary events such as temperature extremes or droughts can have a cumulative effect on social and ecological systems. When complicated by both endogenous and exogenous variables having extensive feedback effects and examined over relevant spatial and temporal scales, these events warrant integrating normal disaster into investment and policy decisions.

Such a comprehensive perspective on natural hazards is, notably, the same one that motivates concern about anthropogenic climate change. Climate change presents a wide-ranging and complex hazard to human populations and ecosystems. It subsumes not only trends in long-term averages of temperature or rainfall, but also droughts, the geographic extent of early thaw, the development and recession of El Ninos and more. Changes in these aspects of climate can stress social systems (e.g., traditional livelihoods, civil society, community organization, social welfare) in multiple ways. First, departures from long-term averages raise the level of background stress, thereby increasing vulnerability to acute stresses. Second, the character or frequency of the acute stresses themselves may change, manifesting as extreme weather events such as hurricanes, droughts or floods. Third, climate change may exacerbate the scope and intensity of chronic hazards and the contributing elements associated with such stresses. For example, the reduction in stabilizing ecosystem services due to environmental degradation--resulting from climate change, or more often from human activities with immediate impact such as logging--exacerbates vulnerability to extreme events.

Disaster management and climate change mitigation therefore both fundamentally seek to reduce the trauma inflicted by natural hazards and to facilitate a smooth recovery from perturbations. This paper examines the interface between these arenas, linking current discussions of hazard preparedness with socioecological resilience and international burden-sharing in a world of changing climate. Drawing on geographically diverse case studies, we argue that long-range climate change mitigation efforts can augment societal resilience to acute and chronic natural hazards in the short-term and furthermore are an important aspect of national security. The comprehensive perspective informs the link between a changing climate and societal vulnerability. It argues for increasing resilience with additional policy mechanisms to transfer and reduce both the expected risks of weather events and the risks of changes in weather patterns due to climate change. Systematic approaches to diversifying climate risk across geography, time and institutions can realize multiple benefits for disaster relief, societal resilience and nations' well-being.

LINKING CLIMATE CHANGE AND DISASTER MANAGEMENT

Concepts of vulnerability, resilience and burden-sharing capacity form a basis for understanding the link between climate change and disaster management. Risk analysts are familiar with the first two factors: vulnerability, which captures a system's sensitivity to perturbations, and resilience, which captures how quickly and easily a perturbed system can recover. In examining both concepts, understanding the potential impact of natural hazards is impossible without understanding their regional and local contexts, including the people, institutions, infrastructure, economy and environment. (4) Defining the characteristics of a "stressed" system relative to a normal one is the focus of vulnerability analysis. (5) Vulnerability itself denotes a fairly straightforward susceptibility to damage, and, like a balloon stretched to its breaking point, it can encompass exposure to perturbation, its baseline sensitivity and how close the system's current state is to a threshold of damage. (6) Importantly, vulnerability can stem from either common stress, such as drought, or more high-profile "rare" natural disasters. On the one hand, weather-related disasters have accounted for nearly 90 percent of global disaster-related economic losses, or $1.4 trillion, and have produced twenty-six of the thirty most expensive insurance losses on record. (7) Yet despite the high profile of those events, about 60 percent of weather-related economic losses derive from more mundane occurrences, such as simple temperature extremes or moderate droughts. (8)

These chronic hazards represent the kind of additional stress that gradual climate change is most likely to introduce into the earth system. The vulnerability of a smallholder farming community, for example, might depend on both a climatic threshold--e.g., how close the expected rainfall is to the minimum viable amount--and on economic diversification or management practices. Stressing or compromising the integrity of any of these regional and local aspects, while perhaps not precipitating a catastrophe independently, can increase vulnerability and decrease resilience when the region is hit with a stress or shock. For example, the inland surge of the 2004 Indian Ocean tsunami was significantly stronger and more damaging in areas along the coast of Sri Lanka where offshore coral reef theft weakened that natural wave barrier. (9)

Sub-Saharan Africa illustrates a more complex, nested interaction of chronic climatic stresses and human activities. (10) In order to increase agricultural production, many African regions utilize extensive or rotation farming systems that clear large areas of forests, degrade the soil and leave little land fallow. Deforestation is the main cause of soil erosion, aggravating desertification and impeding agricultural production. Furthermore, extensive burning of biomass for energy (two-thirds of Africa's energy consumption results from biomass combustion) can exacerbate soil erosion and thus reduce future biomass energy availability. In this case, chronic stresses on people (hunger), economy (agricultural production) and environment (forests and soil) can interact such that a perturbation of any one stress aggravates the balance of the others. Climate change threatens to amplify these problems as changes in the hydrologic cycle and temperature will likely exacerbate soil loss in these regions, thus complicating the human response.

The antidote to vulnerability is resilience. Scholars define resilience as either flexibility in the face of perturbation or, alternately, ease of returning to the original state after disruption. If patterns of climate change are understood in the same way as the hurricane history chart (Figure 1) in that they create repeated perturbations, then increasing societal resilience is one policy goal that addresses both climate change and natural hazards. (11) As a concept that has emerged from the study of ecological systems, resilience retains that field's early emphasis on networks and mutual interdependence; applied to the study of adaptation to climate change, it is usually combined with vulnerability analysis to inform a concept of adaptive capacity. (12) This capacity includes the ability to reduce exposure to climate risks, to absorb and recover from losses and to enable people to exploit new opportunities that arise in a changing environment. (13) Thus, while adaptive capacity stems in part from a country's level of economic development, the geographical context, collective experience and local knowledge often matter more. Indeed, it was institutional readiness and inherited knowledge that allowed fishing communities on Indonesia's Simeulue Island to escape the ravage of the 2004 tsunami, enabled pastoralists in the West African Sahel to adapt to 25-33 percent decreases in rainfall during the 20th century, and fostered in migrants an understanding of geography that enabled sustainable resource use in remote parts of Bangladesh and Vietnam. (14)

Recent activities of communities in the Moroccan High Atlas exemplify potentially resilient approaches to the nested social, ecological and economic vulnerabilities to climate change. (15) These montane agrarian communities' livelihoods depend on livestock, arable production, arboriculture and external incomes such as tourism. Traditionally, systemic stresses have been...