The purpose of this paper is to present a tentative conceptual framework for studies of vulnerability and adaptation to climate variability and change, generally applicable to a wide range of contexts, systems and hazards. Social vulnerability is distinguished from biophysical vulnerability, which is broadly equivalent to the natural hazards concept of risk. The IPCC definition of vulnerability is discussed within this context, which helps us to reconcile apparently contradictory definitions of vulnerability. A concise typology of physically defined hazards is presented; the relationship between the vulnerability and adaptive capacity of a human system depends critically on the nature of the hazard faced. Adaptation by a system may be inhibited by process originating outside the system; it is therefore important to consider “external” obstacles to adaptation, and links across scales, when assessing adaptive capacity.
The forests of northern Wisconsin will likely experience dramatic changes over the next 100 years as a result of climate change. This assessment evaluates key forest ecosystem vulnerabilities to climate change across northern Wisconsin under a range of future climate scenarios with a focus on the Chequamegon-Nicolet National Forest. We describe the contemporary landscape and major existing climate trends using state climatological data, as well as potential future climate trends for this region using downscaled global data from general circulation models. We identify potential vulnerabilities by incorporating these future climate projections into species distribution and ecosystem process models and assessing potential changes to northern Wisconsin forests. Warmer temperatures and shifting precipitation patterns are expected to infl uence ecosystem drivers and increase stressors, including more frequent disturbances and increased amount or severity of pests and diseases. Forest ecosystems will continue to adapt to changing conditions. Even under conservative climate change scenarios, suitable habitat for many tree species is expected to move northward. Many species, including balsam fi r, white spruce, paper birch, and quaking aspen, are projected to decline as their suitable habitat decreases in quality and extent. Certain species, communities, and ecosystems may not be particularly resilient to the increases in stress or changes in habitat, and they may be subject to severe declines in abundance or may be lost entirely from the landscape. These include fragmented and static ecosystems, as well as ecosystems containing rare species or species already in decline. Identifying vulnerable species and forests can help landowners, managers, regulators, and policymakers establish priorities for management and monitoring.