Modeling tropical land use change and assessing policies to reduce carbon dioxide release from Africa.

摘要

Humans may be causing the climate to change in ways that could threaten the welfare of future generations. The alteration by humans of the earth's remaining tropical forests is a component of the atmospheric flux of carbon dioxide, the most important greenhouse gas. It is especially important to investigate this flux because our understanding of it is highly uncertain, and it is a component of the global carbon cycle that humans can regulate. This dissertation supplies scientific tools and socioeconomic insights that policy makers may use to help to decide how much, if at all, to reduce the anthropogenic release of carbon dioxide from tropical landscapes.;Chapter 1 presents a new Geographic Information System (GIS) model called GEOMOD2, which is a computer program written in FORTRAN. GEOMOD2 simulates land use change forward and backward in time using a digital map of land use, and produces a map of simulated carbon dioxide flux due to land use change. GEOMOD2 selects land for conversion according to patterns of previous land use and rates of land use change. Chapter 1 applies GEOMOD2 to tropical Africa, but the model could be used in other parts of the world and for a wider variety of applications.;Chapter 2 uses the kappa parameter and an extraordinarily complete data set for Costa Rica to examine the accuracy with which GEOMOD2 predicts land use patterns. GEOMOD2 simulates the pattern of land use in Costa Rica over a duration of more than four decades with a success rate between 74% and 84% (kappa between 0.32 and 0.44).;Chapter 3 uses an ecological economics approach to assess policies to reduce the amount of carbon dioxide being released from African agriculture. It concludes that the application of fertilizer to existing African fields would supply additional needed food to Africans at minimum carbon dioxide release, compared with other methods such as food importation, expanded shifting cultivation, or newly created permanent cultivation.