An alternative model, the so-called “vulnerability model,” accounts directly for all of the factors contributing to an effect. The vulnerability model is based on a simple framework that integrates impacts with mitigation and adaptation strategies (Figure 1). We intuitively understand the concept of vulnerability. For example, if a health threat, such as a new infectious disease arises, the public health community rapidly provides drugs or therapies to address the threat. The smaller the difference between the impact (the potential for a disease) and the adaptation strategy (the effectiveness of the drug) the smaller the vulnerability to this health threat. Occasionally, a virulent, highly contagious disease like the Ebola virus arises. This virus acts so quickly that there is virtually nothing we can do to adapt. Hence, in this case, our vulnerability is very great.

In responding to climate change, the engineering and technological community can both mitigate the effects and adapt our capabilities. Mitigation strategies can reduce the impacts, thereby reducing vulnerabilities; vulnerabilities can be reduced further by improving our adaptative capacities. We need a new “calculus,” an improved vulnerability model that connects these three elements (the climate change, mitigation strategies, and adaptations), both conceptually and analytically, that would enable us to address our vulnerabilities more holistically.

The vulnerability approach is based on an understanding that accelerating rates of change in the Earth’s climate, air and water quality, and humankind’s use of land, natural resources, and ecosystems affect the well-being of societies and

FIGURE 1 The vulnerability model.