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Vulnerability assessments: Synthesis and application for aquatic species and their habitats in the western U.S.

September, 2013 to March, 2015


The western U.S. is expected to see increased water stress index by mid-century (2040-61) as compared to historic averages (1900-1970) (image from Averyt et al. 2013).
The western U.S. is expected to see increased water stress index by mid-century (2040-61) as compared to historic averages (1900-1970) (image from Averyt et al. 2013).
The conservation of western riparian systems is of particular concern because these areas support a disproportionate amount of the regional biodiversity and are likely to be strongly affected by changes in climate (Seager et al. 2007; Field et al. 2007; Furniss et al. 2012). The Southern Rockies Landscape Conservation Cooperative (LCC), recognizing the need for syntheses and tools for climate change adaptation, sponsored this effort. The Southern Rockies LCC encompasses the Upper Colorado River Basin and portions of the Lower Colorado and Rio Grande Basins. These systems represent some of the most critical water sources in the West and are likely to experience some of the most extreme changes in climate (Christensen et al. 2007; Theobald et al. 2010; Furniss et al. 2012).

Project Objectives

The aquatics synthesis project aimed to improve access and application of relevant climate change data for resource managers based on a review and synthesis of vulnerability assessments for aquatic species and habitats across the West.

Vulnerability assessments employ a systematic method for measuring and addressing information on potential climate change impacts for a region or resource of interest (Glick et al. 2011; Friggens et al. 2013). The primary benefit of vulnerability assessments is that they supply a system to rank relative targets according to their expected response to climate related impacts and provide information pinpointing the cause of vulnerability for valued resources. Vulnerability assessments consider not only expected response of resources, but also examine the way in which a resource is affected, often in relation to other resources, to better identify management intervention points.

However, to benefit from currently available vulnerability assessments, managers must be able to access and understand information regarding their management target, which is hindered by the diversity of the current vulnerability literature. Selecting the appropriate type of assessment requires a clear understanding of how assessments are conducted and how vulnerability measures inform adaptive management actions.

This project (1) provided guidance for managers and conservationists interested in using vulnerability assessments to identify vulnerabilities and management strategies and (2) enabled better access to and interpretation of currently available data, and (3) helped effectively link vulnerability assessments with management questions and actions.

Key Findings

Matching photographs taken 18 months apart during the most serious period of recent drought show a significant decrease in Lake Powell (photos by John Dohrenwend).
Matching photographs taken 18 months apart during the most serious period of recent drought show a significant decrease in Lake Powell (photos by John Dohrenwend).
Researchers identified 43 vulnerability assessments and 225 impact studies that address climate change and aquatic systems in the western U.S. Some general findings from this review include:

  • Targets and methods to measure vulnerability vary widely among vulnerability assessments. The place-based nature of vulnerability assessments helps tailor them to local management needs but hinders meaningful comparative analysis at larger scales.

  • Aquatic vulnerability assessments tend to focus on the innate qualities of ecosystems or hydrological processes that indicate high sensitivity. Further, external non-climate stressors are often identified as the most problematic sources of vulnerability of aquatic systems and species under future conditions. In particular, over allocation (demand exceeding natural flow) and disrupted natural flows (e.g., dams) were commonly implicated issues. This focus and its apparent importance for predicting aquatic system vulnerability indicates a need for management activities that aim to reduce the impact of non-climate stressors.

  • The majority of assessments consider water resources in context of the provision of services to the human sector. As a result, many aquatic assessments include considerations for both human and ecosystem vulnerability.

  • Scale has an important influence on the degree to which aquatic ecosystems are considered at risk of negative impact due to climate change effects. Local-scale impacts may lead to habitat or species loss that is not captured by more generalized, large-scale assessments.

  • Biophysical characteristics were most predictive of vulnerability at larger scales. Location, elevation, parent materials, and even latitude related directly to the innate sensitivity of systems to climate related changes. Biota, water quality, and exposure to stressors were more commonly used to determine the resiliency of the system to disturbances at local scales.

To learn more about this topic, see the Science Spotlight Climate change vulnerability of wildlife in Southwestern U.S. riparian habitats.


Friggens, M. ; Bagne, K. ; Finch, Deborah M. ; Falk, D. ; Triepke, J. ; Lynch, Ann M. , 2013


  • Final project report that reviews and discusses the vulnerability assessment literature focused on riparian and aquatic systems in the Western U.S.

  • Literature list and annotated bibliography for vulnerability assessments and climate change studies related to riparian and aquatic systems at the global, national, regional, and state levels



Averyt, K.; J. Meldrum; P. Caldwell; G. Sun; S. McNulty; A. Huber-Lee; and N. Madden. 2013. Sectoral contributions to surface water stress in the coterminous United States. Environmental Research Letters 8: 035046 (9pp). doi:10.1088/1748-9326/8/3/035046.

Christensen, N.; and D. Lettenmaier. 2007. A multimodal ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin. Hydrology and Earth System Sciences 11: 1417-1434.

Field, C.; L. Mortsch; M. Brklacich; et al. 2007. Chapter 14: North America. Pages 617-652 in Marry, Costanza, Palutikoff et al., (eds.). Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, New York, NY.

Friggens, M.; K. Bagne; D. Finch; D. Falk; J. Triepke; and A. Lynch. 2013. Review and recommendations for climate change vulnerability assessment approaches with examples from the Southwest. Gen. Tech. Rep. RMRS-GTR-309. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 106 p.

Furniss, M. J.; K. B. Roby; D. Cenderelli; et al. 2013. Assessing the vulnerability of watersheds to climate change: Results of national forest watershed vulnerability pilot assessments. Gen. Tech. Rep. PNW-GTR-884. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 32 p. plus appendix.

Glick, P.; B. A. Stein; and N. A. Edelson (eds.). 2011. Scanning the conservation horizon: A guide to climate change vulnerability assessment. National Wildlife Federation, Washington, D.C. 168 p.

Seager, R., et al.. 2007. Model predictions of an imminent transition to a more arid climate in Southwestern North America. Science 316: 1181-1184.

Theobald, D.; D. Merritt; and J. Norman, III. 2010. Assessment of threats to riparian ecosystems in the Western U.S. A report presented to The Western Environmental Threats Assessment Center, Priveville, OR: USDA Stream Systems Technology Center and Colorado State University, Fort Collins. 61 p.

Project Contact: 

Principal Investigators:
Research Staff:
Funding Contributors:
Southern Rockies Landscape Conservation Cooperative