The IPCC defines vulnerability as a function of the sensitivity of a particular system to climate changes, its exposure to those changes, and its capacity to adapt to those changes (IPCC 2007c). Sensitivity is a measure of whether and how a species or system is likely to be affected by a given change in climate. Exposure is a measure of how much of a change in climate and associated problems a species or system is likely to experience. Adaptive capacity refers to the opportunities that may exist to ameliorate the sensitivity or exposure of that species or system. The relationship among these three components is outlined schematically in Figure 2.1. Considering the degree of change (i.e., exposure) that a species or system is projected to experience along with its likely response (i.e., sensitivity) to those changes determines the potential impact. Understanding the likely consequences (i.e., vulnerability), however, requires further consideration of the ability for the species or system to reduce or moderate those potential impacts (i.e., its adaptive capacity).