In summary, the sensitivety study presented in this chapter supports the overall theme of this book (i.e., that fires in the boreal forest play a central role in the exchange of carbon between this biome and the atmosphere). Through a series of processes, the continuing rise in atmospheric temperatures projected for this region will act to release much of the carbon stored in the deep organic soils present in this region. Under the worst-case scenario presented in this chapter, the upper organic-soil layers of the North American boreal forest will lose more than 50% of their stored carbon if the projected rises in atmospheric temperature occur. Because much of this carbon took centuries to millennia to accumulate, this represents a net loss of carbon to the atmosphere. In effect, fire represents a positive feedback to the atmosphere because the gases released from fires will serve to increase the rates of flobal warming.