The impact of anthropogenic global land cover: Transformation on the land-atmosphere fluxes of the water and carbon cycles

By altering surface aerodynamic, thermodynamic, radiative, hydrologic and vegetative properties, land cover change directly alters land surface fluxes of water (evapotranspiration, ET) and carbon (net primary productivity, NPP). Despite the pervasive human impact on the global hydrologic and carbon cycles, robust estimates of such human impact are lacking. The goal of this thesis is to further our knowledge on the extent of human impact on the planet by advancing our understanding of uncertainties of and improving the current statistics of global-scale human land cover change impact on the global water cycle and carbon cycle, and to make estimates of the net change in global annual NPP and ET, and, finally to identify the areas of greatest change in surface fluxes from land cover change on the earth.; In Chapter 1 I estimate the impact of land cover change on NPP with the use of recent NPP and land cover change, data, many of which were collected at global and continental scales. Monte Carlo techniques that incorporate known and estimated error in the parameters provide estimates of uncertainty. Results indicate that humans appropriate 10 to 55% of terrestrial photosynthesis products.; In Chapter 2, I present data on land cover change and regional and local estimates of ET to estimate human impact on land cover and ET, and resulting changes in the annual fluxes of ET and NPP. I show that by occupying 41 percent of all land, where over half of terrestrial ET (TET) occurs, humanity is slowing down the global water and carbon cycles, reducing annual ET and NPP on average by -3.8 and -6.2 percent respectively, although uncertainty in these estimates is high.; Global-scale summaries mask potentially important regional patterns of altered hydrology from land cover change. In Chapter 3 I investigate global patterns in change in annual ET from land cover change by applying the observational ET database to a series of adapted global land cover maps, using Geographic Information Systems (GIS).; The results of the study provide information to scientists, governments, and international organizations to aid the identification of the areas in the globe that are undergoing a water crisis that may be caused or exacerbated by land cover change; they allow us to identify regions where human modification of the landscape might be expected to alter precipitation patterns. (Abstract shortened by UMI.)...