Evaluating the land use change carbon flux and its impact on climate

Carbon emissions from Land Use and Land Cover Change (LULCC) are currently about 30% of total anthropogenic CO 2 emissions. However, our ability to estimate the net effect of LULCC on atmospheric CO 2 concentrations is limited by uncertainties associated with carbon fluxes from land conversion. The current generation of climate-carbon models does not generally include LULCC dynamically in the simulations and as a result, carbon emissions from LULCC have typically been specified externally rather than simulated interactively by model. In addition, the extent of LULCC in model simulations has usually been limited to the extent of crops. In order to address these uncertainties, this research develops the land component of an intermediate-complexity coupled climate-carbon model - the University of Victoria Earth System Climate Model (UVic ESCM v.2.8). For that (1) the area of the agricultural land used to drive the model simulations was extended to include the pasture area, and (2) a dynamic 'bookkeeping' carbon accounting scheme was integrated into the UVic ESCM terrestrial component. The new scheme interactively allocates vegetation carbon displaced as a result of a specified LULCC to direct CO 2 emissions, as well as to short- and long-lived pools with varying decay timescales. This allows running transient simulations of the CO 2 emissions due to historical patterns of LULCC as well as, combined with use of the newest global datasets of crops and pastures, provides improved estimates of the net contribution of land use changes to climate