Linda Joyce , Rocky Mountain Research Station, US Forest Service, Fort Collins, CO, and Maria Janowiak , Northern Institute of Applied Climate Science, US Forest Service, Houghton, MI.
As knowledge about the effects of climate change grows, responses to climate change become more important to land managers (1, 2, 3). Climate change vulnerability assessments provide valuable information that can be used to develop management actions in response to climate change (4). These assessments synthesize and integrate scientific information, quantitative analyses, and expert-derived information in order to determine the degree to which specific resources, ecosystems, or other features of interest are susceptible to the effects of climate change, including climate variability and extremes. Vulnerability assessments recognize that a system's vulnerability is related to the nature, magnitude, and variability of climate change that it is exposed to, as well as the system's sensitivity to changes and its capacity to adapt.
Vulnerability assessments are increasingly being used to assess risks associated with climate change and natural and human systems (5). The information and methods used to create assessments vary widely across resources and sectors, although there are a number of notable similarities. Vulnerability assessments are often most valuable when they are "place-based" and tailored to best fit the resource or system of interest, the geographic scale and location of the analysis area, the available sources of information, and management issues or concerns (6). Because climate change assessments inform conservation or management actions, the tools developed to support the use of the assessment results should be tailored to the relevant geographic scales and decision levels (7).
Vulnerability assessments, like other climate change assessments, specifically work to recognize, evaluate, and communicate the uncertainties associated with climate change within a system or area of interest. While much is known about the effects of climate change at a global scale, the ability to analyze effects and vulnerabilities at the regional and local scales important to managers is more challenging and has a higher level of scientific uncertainty. Vulnerability assessments often use multiple scenarios of future conditions or other quantitative methods to explore areas of uncertainty and to evaluate impacts and potential management strategies against a range of plausible futures. Some recent assessments attempt to describe the uncertainty associated with the reports' conclusions (e.g., 8, 9).
Vulnerability assessments typically contain a synthesis of the currently available scientific information to describe the degree to which the key resources, ecosystems, or other features of interest are affected (adversely or beneficially) by the variability of current climate or the potential changes in climate. The effect may be direct (e.g., reduced regeneration in response to increased temperatures) or indirect (e.g., damages caused by an increase in the frequency of wildfire or drought). The amount of information on climate change effects is constantly increasing so that this synthesis can be developed using a number of existing resources, including climate change impact assessments, peer-reviewed research papers, and other reports and resources.
Because existing information resources may not be able to fully describe the vulnerability for the specific area of focus, assessments can also include a more extensive quantitative analysis to explore a variety of future climates and their effects. New area-specific analyses can be used to enhance what is already known. A number of different quantitative approaches may be taken, such as simulation or statistical models, and will depend upon the feature of interest. The use of multiple scenarios of greenhouse gas emissions and multiple climate models can facilitate the exploration of a range of future climate conditions. Further, the use of multiple biological and ecological models can help to determine the range of sensitivity of and exposure of climate change to key resources.
Within the area of interest, human activities can both depend upon and influence natural systems. Describing the interactions of current stressors, such as land use change, with ecosystem dynamics and associated human systems will help establish the context in which the current and future effects of climate change may take place. Approaches to identify societal vulnerabilities to future changes in resources and ecosystems dynamics have used quantitative and qualitative methods (10, 11). Consideration of the societal implications of climate change can provide a broader view of management challenges posed by climate change and may begin a discussion of the role of communities in the context of changing resources and ecosystems.
Drawing upon the expertise of scientists, land managers, and stakeholders can enhance the quality and relevance of a vulnerability assessment. There will be multiple types and sources of information used in the vulnerability assessment, and this information will be integrated across the specific resources, ecosystems, or other features of interest. Scientists and managers can be assembled to use their place-based knowledge and experience to synthesize the existing and new information and identify the vulnerabilities for the features of interest. Expert-derived information is most valuable when qualified regarding the certainty, evidence, and underlying assumptions and reasoning (4).
Vulnerability assessments do not set priorities or make decisions for management action. Instead, they inform the development of management activities, such as where to focus management efforts or what items should be monitored (4). The assessment may identify where monitoring might be valuable to gain more information on the status of species or habitats and their responses to changes in climate. Additionally, the assessment may include information on adaptation options that may be available to managers.