Climate Change

Johnsen- SFSCh.30

Global change is predicated due to human-induced increases in greenhouse gases (chiefly CO₂) in the atmosphere. Current increases in atmospheric CO₂ are well documented and are due to the combustion of fossil fuel and other human activities. Atmospheric CO₂ concentrations are currently over 365 parts per million, 35 percent higher than preindustrial values. They are increasing at a rate of about 0.5 percent per year and are predicted to equal or exceed 550 parts per million by the middle of this century (Wigley and others 1996). Thus, the first basic cog in the global change physical machinery is clearly engaged, but the ramifications for potential consequences are in the realm of scientifically derived probabilities. Science endeavors to provide systematic methods for evaluating current and anticipated ecosystem function and composition given projected conditions, and to provide information that can guide ecological, economic, and social decisions that are made by landowners, corporations, and governments.

Fig 31.1 SFS Ch 31 earth temp record

Predictions and discussions of potential global change have existed in both the scientific and political arenas. Gucinski and others (2004) provide a discussion on discriminating fact from fiction in this polarized debate. They discuss the evidence that global change is currently impacting climate and consider predictions of future climate scenarios. Their major conclusion is that the climate is likely to change given historical climate variation and the possibility that an accelerating greenhouse effect is in progress.

Mitigating negative climate change impacts on Southern U.S. forests will be an important consideration regarding future climate scenarios. Forest carbon sequestration can provide a short- to medium-term offset for atmospheric CO₂ emissions, while potential additional carbon sinks are filled. Additionally, utilization of woody biomass for bioenergy production can provide long-term offsets, as these partly supplant fossil fuel combustion.

In the sections that follow, an overview of the concept of carbon sequestration is provided as well as current estimates of forest carbon, details of a Loblolly Pine case study in carbon sequestration, and a model plan for landowner carbon credits is presented.