The University of Arizona

Assessing Vulnerability to Climate Change

By Joe Abraham | The University of Arizona | June 17, 2009

In the Southwest, projected impacts of climate change, such as drier winters, less snowpack, and more frequent droughts, will likely have significant consequences for the environment, the economy, and quality of life in the region. Faced with the possibility of reduced water supplies, more wildfires, and increased public health risks, government agencies, communities, and other organizations are starting to incorporate climate change into their long-term planning as a means of reducing their vulnerability to these and other related impacts.

photo of solar panels on a house

Stakeholder involvement is important for assessing vulnerability to climate variability and change.
Credit: ©Alice Scully,

In a very general sense, planning for climate change involves three critical steps: assessing climate impacts, assessing vulnerability, and developing a strategy for adapting to climate changes. In the second step, assessing vulnerability, agencies and organizations address two questions: 1) How will specific systems such as threatened ecosystems, transportation infrastructure, or public health, be adversely affected by climate impacts; and 2) How will various non-climatic factors like encroaching development, aging infrastructure, or community cohesion enable or constrain an organization to manage additional risk resulting from climate impacts?

A variety of approaches have been developed for assessing vulnerability that draw on a large interdisciplinary body of research.1,2,3,4 Climate policy advocacy groups, researchers, and governments around the world have collaborated to translate this research into climate adaptation planning guides to support governments, businesses, and other organizations planning for climate change. While the definition of vulnerability and how it should be assessed varies in both the research and in the planning guides, it typically is presented as a condition of three inter-related factors:

This page introduces and briefly discusses these concepts within the context of conducting a vulnerability assessment as part of a climate adaptation planning process. Organizations developing an adaptation plan are encouraged to develop a process of assessing vulnerability that incorporates these concepts. Climate adaptation planning guides included on this Web site provide additional discussion and examples.

Exposure to impacts

Graph of transportation emission reduction recommendations

Figure 1. The State of California is determining its exposure to sea-level rise as part of a broader climate impact assessment and adaptation planning process.
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Credit: Joe Abraham, adapted from map produced by the Pacific Institute.

Building on a climate impact assessment, vulnerability assessments generally begin by evaluating how specific systems, such as roadways, water resources, and critical habitat, are “exposed” to climate impacts. For example, more homes near desert washes may be exposed to flooding due to more intense or frequent flood events. Also, critical habitat may be more exposed to invasive species that can expand into higher elevations with climate change. In many cases, organizations can infer general changes in exposure by reviewing climate change impact reports or the impact assessments for the Southwest on this Web site. Depending on the situation, however, results of research may be too general, requiring organizations to conduct additional research to determine exposure.

With additional research it is possible to improve upon general assessments of climate impacts and produce more specific assessments of exposure. Figure 1 illustrates how, with the use of Geographic Information Systems (GIS), the Pacific Institute was able to take estimates of sea-level rise and produce high resolution maps of how the California coastline’s exposure to coastal flooding will change. Climate scientists are increasingly downscaling global climate models to generate higher-resolution climate change estimates. These then can be used in regional and even local-scale hydrologic, ecological, and other computer models to produce higher resolution estimates of projected impacts. In general, more specific information about exposure is likely to help reduce uncertainty and result in a more informed and targeted set of adaptation strategies.

Sensitivity to impacts

There is likely to be significant variation in how animals, agricultural crops, rivers, etc., will be affected by climate change. Within the context of developing a climate adaptation plan, sensitivity refers to the degree a resource, population, etc., changes relative to incremental changes in the climate. As a result, sensitivity is a useful concept for describing how systems are more or less vulnerable to climate change. For example, a community water system with access to surface and groundwater resources is likely to be less vulnerable to water shortages than if it only had access to surface water, which may be reduced as a result of drier winters and reduced snowpack. Also, vulnerability to extreme heat varies in a community because some individuals are more sensitive to heat-related stress and illness than others.

Organizations can draw on a range of sources of information to assess sensitivity. In some cases, they may be able to use computer models to evaluate the sensitivity of specific watersheds or ecological systems to changes in temperature and precipitation patterns. In the case of public health, an agency may draw on the experiences of citizens, community groups, and university researchers to identify public health sensitivities like increased incidence of heat stress, drinking water contamination, or disease related to past droughts, floods, and other weather and climate patterns projected to occur more often as a result of climate change.

Graph of transportation emission reduction recommendations

Figure 2. Adaptive capacity helps to reduce vulnerability and increase resilience to climate change.
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Credit: Image adapted by Joe Abraham from Climate Adaptation: Risk, Uncertainty and Decision-making, UKCIP 2003.

Capacity to adapt to impacts

Adaptive capacity refers to the ability of natural, social, and economic systems to accommodate changes in climate, reduce or manage vulnerability, and limit adverse consequences5,6. It can reflect the intrinsic qualities of a system that make it more or less capable of adapting, such as the cooperative relationships between species in an ecosystem, the presence of effective leaders and organizers in a community, or the relative abundance of shaded parks in an urban environment. Adaptive capacity can also reflect the abilities of the agency or organization responsible for managing an ecosystem, leading a community, or urban public spaces. Their capacity to adapt is determined by a range of issues, including the ability to collect and analyze information, communicate, plan, and implement adaptation strategies that ultimately reduce vulnerability to climate change impacts.

Organizations likely have access to a range of resources from which they can assess adaptive capacity, including the institutional knowledge of managers and staff, partner communities and stakeholders, and others. It is important that an assessment of adaptive capacity be informed by and reflective of exposure and sensitivity to climate impacts. In doing so, organizations can focus on who or what is adapting and how that adaptation may occur.

Related Links

National Center for Atmospheric Research GIS Climate Change model data portal
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UNFCC Compendium on methods and tools to evaluate impacts, assess vulnerability, and adaptation to climate change
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United Nations Environmental Program Knowledge Network on Vulnerability and Adaptation to Climate Change
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CSIRO working paper on assessing climate change vulnerability and adaptive capacity
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  1. Carter, T.R., et al. 2007. New Assessment Methods and the Characterisation of Future Conditions. Climate Change 2007: Impacts, Adaptation and Vulnerability of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 133-171.
  2. Adger, W. N.. 2006. Vulnerability. Global Environmental Change, 16(3): 268-271.
  3. Brooks, N.. 2003. Vulnerability, Risk and Adaptation: A Conceptual Framework. Tyndall Centre for Climate Change Research Working Paper 38.
  4. Fussel, H. M., and R. J. T. Klein. 2006. Climate change vulnerability assessments: an evolution of conceptual thinking. Climatic Change, 75(3): 301-329.
  5. Folke, C.. 2006. Resilience: the emergence of a perspective for social-ecological systems analyses. Global Environmental Change, 16(3): 253-267.
  6. Smit, B., and J. Wandel. 2006. Adaptation, adaptive capacity, and vulnerability. Global Environmental Change, 16(3): 282-292.