Land-based activities are responsible for a large part of global greenhouse gas (GHG) emissions, yet the economics of land-use decisions have rarely been explicitly modeled in global mitigation studies. This paper integrates the analysis of land use related non-CO2 emissions and carbon forest sequestration with more conventional analyses of CO2 emissions from fossil fuel combustion to provide a comprehensive assessment of the relative role of land in global GHG emissions and mitigation. For this paper, we utilize a new general equilibrium framework which effectively captures the opportunity costs of land-use decisions in agriculture and forestry, the implications of these decisions for GHG emissions, as well as mitigation options in agriculture and forestry. By combining this with a more conventional analysis of fossil fuel-based CO2 emissions mitigation, we are able to analyze trade-offs and feedbacks between GHG emissions reductions in land-based and fossil fuel combustion intensive sectors. We explore the general equilibrium effects when land rents are endogenous and large-scale adoption of mitigation technologies produces feedbacks across sectors and regions.